From 50d1085fcee239f3ac6e897f95d4d77b4c7e666e Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Tue, 17 Aug 2021 21:14:11 +0800
Subject: [PATCH 01/32] Basic bazel setup.

---
 .gitignore                                            | 4 ++++
 BUILD                                                 | 6 ++++++
 WORKSPACE                                             | 0
 src/main/java/{ => com/lockarhythm/cmdline}/Duke.java | 2 ++
 4 files changed, 12 insertions(+)
 create mode 100644 BUILD
 create mode 100644 WORKSPACE
 rename src/main/java/{ => com/lockarhythm/cmdline}/Duke.java (91%)

diff --git a/.gitignore b/.gitignore
index f69985ef..8256048a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,7 @@ bin/
 
 /text-ui-test/ACTUAL.txt
 text-ui-test/EXPECTED-UNIX.TXT
+
+# Ignore all bazel-* symlinks. There is no full list since this can change
+# based on the name of the directory bazel is cloned into.
+/bazel-*
diff --git a/BUILD b/BUILD
new file mode 100644
index 00000000..39bca6aa
--- /dev/null
+++ b/BUILD
@@ -0,0 +1,6 @@
+load("@rules_java//java:defs.bzl", "java_binary")
+
+java_binary(
+    name = "Duke",
+    srcs = glob(["src/main/java/com/lockarhythm/cmdline/*.java"]),
+)
diff --git a/WORKSPACE b/WORKSPACE
new file mode 100644
index 00000000..e69de29b
diff --git a/src/main/java/Duke.java b/src/main/java/com/lockarhythm/cmdline/Duke.java
similarity index 91%
rename from src/main/java/Duke.java
rename to src/main/java/com/lockarhythm/cmdline/Duke.java
index 5d313334..b6a76693 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/com/lockarhythm/cmdline/Duke.java
@@ -1,3 +1,5 @@
+package com.lockarhythm.cmdline;
+
 public class Duke {
     public static void main(String[] args) {
         String logo = " ____        _        \n"

From b5eb9ac02d5e0210821512169b18691f6bc859ea Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Tue, 17 Aug 2021 21:17:39 +0800
Subject: [PATCH 02/32] Update documentation.

---
 README.md | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/README.md b/README.md
index 8715d4d9..76435deb 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,14 @@
 
 This is a project template for a greenfield Java project. It's named after the Java mascot _Duke_. Given below are instructions on how to use it.
 
+## Local Build
+Prerequisites: Have `bazel` installed.
+```bash
+# Following tested on OSX.
+bazel build //:Duke
+./bazel-bin/Duke
+```
+
 ## Setting up in Intellij
 
 Prerequisites: JDK 11, update Intellij to the most recent version.

From 7aa0bffeea7ef399bdd2b79a2126077edf4c527e Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Tue, 17 Aug 2021 22:36:13 +0800
Subject: [PATCH 03/32] Add unit test, test runner and refactor.

---
 BUILD                                         | 11 ++++++++++
 README.md                                     |  6 ++++++
 .../java/com/lockarhythm/cmdline/Duke.java    | 16 ++++++++------
 .../com/lockarhythm/cmdline/TestDuke.java     | 21 +++++++++++++++++++
 4 files changed, 48 insertions(+), 6 deletions(-)
 create mode 100644 src/test/java/com/lockarhythm/cmdline/TestDuke.java

diff --git a/BUILD b/BUILD
index 39bca6aa..5f4fa483 100644
--- a/BUILD
+++ b/BUILD
@@ -1,6 +1,17 @@
 load("@rules_java//java:defs.bzl", "java_binary")
+load("@rules_java//java:defs.bzl", "java_test")
 
 java_binary(
     name = "Duke",
     srcs = glob(["src/main/java/com/lockarhythm/cmdline/*.java"]),
 )
+
+java_test(
+    name = "AllTests",
+    size = "small",
+    test_class = "com.lockarhythm.cmdline.TestDuke",
+    srcs = glob([
+        "src/main/java/com/lockarhythm/cmdline/*.java",
+        "src/test/java/com/lockarhythm/cmdline/*.java",
+    ]),
+)
diff --git a/README.md b/README.md
index 76435deb..e511e631 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,12 @@ bazel build //:Duke
 ./bazel-bin/Duke
 ```
 
+## Testing
+
+```bash
+bazel test --test_output=all //...
+```
+
 ## Setting up in Intellij
 
 Prerequisites: JDK 11, update Intellij to the most recent version.
diff --git a/src/main/java/com/lockarhythm/cmdline/Duke.java b/src/main/java/com/lockarhythm/cmdline/Duke.java
index b6a76693..f6bed387 100644
--- a/src/main/java/com/lockarhythm/cmdline/Duke.java
+++ b/src/main/java/com/lockarhythm/cmdline/Duke.java
@@ -1,12 +1,16 @@
 package com.lockarhythm.cmdline;
 
+import java.io.PrintStream;
+
 public class Duke {
+    static PrintStream out = System.out;
+    static String logo =   " ____        _        \n"
+                         + "|  _ \\ _   _| | _____ \n"
+                         + "| | | | | | | |/ / _ \\\n"
+                         + "| |_| | |_| |   <  __/\n"
+                         + "|____/ \\__,_|_|\\_\\___|\n";
+
     public static void main(String[] args) {
-        String logo = " ____        _        \n"
-                + "|  _ \\ _   _| | _____ \n"
-                + "| | | | | | | |/ / _ \\\n"
-                + "| |_| | |_| |   <  __/\n"
-                + "|____/ \\__,_|_|\\_\\___|\n";
-        System.out.println("Hello from\n" + logo);
+        out.println("Hello from\n" + logo);
     }
 }
diff --git a/src/test/java/com/lockarhythm/cmdline/TestDuke.java b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
new file mode 100644
index 00000000..5665dd5b
--- /dev/null
+++ b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
@@ -0,0 +1,21 @@
+package com.lockarhythm.cmdline;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.nio.charset.StandardCharsets;
+
+public class TestDuke {
+
+    @Test
+    public void testNoArgument() throws Exception {
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        Duke.out = new PrintStream(out);
+        Duke.main(null);
+        assertEquals(("Hello from\n"+Duke.logo).trim(), new String(out.toByteArray(), StandardCharsets.UTF_8).trim());
+    }
+
+}

From f659ebbf42051134f2e407896a09c35db482765c Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Tue, 17 Aug 2021 23:58:19 +0800
Subject: [PATCH 04/32] Cleaner test.

---
 src/main/java/com/lockarhythm/cmdline/Duke.java     | 5 +----
 src/test/java/com/lockarhythm/cmdline/TestDuke.java | 9 +++++----
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/src/main/java/com/lockarhythm/cmdline/Duke.java b/src/main/java/com/lockarhythm/cmdline/Duke.java
index f6bed387..06051852 100644
--- a/src/main/java/com/lockarhythm/cmdline/Duke.java
+++ b/src/main/java/com/lockarhythm/cmdline/Duke.java
@@ -1,9 +1,6 @@
 package com.lockarhythm.cmdline;
 
-import java.io.PrintStream;
-
 public class Duke {
-    static PrintStream out = System.out;
     static String logo =   " ____        _        \n"
                          + "|  _ \\ _   _| | _____ \n"
                          + "| | | | | | | |/ / _ \\\n"
@@ -11,6 +8,6 @@ public class Duke {
                          + "|____/ \\__,_|_|\\_\\___|\n";
 
     public static void main(String[] args) {
-        out.println("Hello from\n" + logo);
+        System.out.println("Hello from\n" + logo);
     }
 }
diff --git a/src/test/java/com/lockarhythm/cmdline/TestDuke.java b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
index 5665dd5b..2a0d9a5b 100644
--- a/src/test/java/com/lockarhythm/cmdline/TestDuke.java
+++ b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
@@ -6,16 +6,17 @@
 
 import java.io.ByteArrayOutputStream;
 import java.io.PrintStream;
-import java.nio.charset.StandardCharsets;
 
 public class TestDuke {
+    private final PrintStream standardOut = System.out;
+    private final ByteArrayOutputStream out = new ByteArrayOutputStream();
 
     @Test
     public void testNoArgument() throws Exception {
-        ByteArrayOutputStream out = new ByteArrayOutputStream();
-        Duke.out = new PrintStream(out);
+        System.setOut(new PrintStream(out));
         Duke.main(null);
-        assertEquals(("Hello from\n"+Duke.logo).trim(), new String(out.toByteArray(), StandardCharsets.UTF_8).trim());
+        assertEquals(("Hello from\n"+Duke.logo).trim(), out.toString().trim());
+        System.setOut(standardOut);
     }
 
 }

From 1e8da3d60bb220c08dd05462e086de4576e0b40d Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Fri, 20 Aug 2021 21:18:03 +0800
Subject: [PATCH 05/32] Split into packages. Implement Level 1.

---
 BUILD                                         | 30 ++++++++--
 WORKSPACE                                     | 25 ++++++++
 .../java/com/lockarhythm/cmdline/Duke.java    | 57 +++++++++++++++++--
 .../responders/QueryRespondable.java          |  5 ++
 .../com/lockarhythm/responders/Response.java  | 19 +++++++
 .../responders/echo/EchoResponder.java        | 10 ++++
 .../responders/exit/ExitResponder.java        | 13 +++++
 .../com/lockarhythm/cmdline/TestDuke.java     | 23 +++++++-
 .../responders/echo/TestEchoResponder.java    | 18 ++++++
 .../responders/exit/TestExitResponder.java    | 25 ++++++++
 10 files changed, 211 insertions(+), 14 deletions(-)
 create mode 100644 src/main/java/com/lockarhythm/responders/QueryRespondable.java
 create mode 100644 src/main/java/com/lockarhythm/responders/Response.java
 create mode 100644 src/main/java/com/lockarhythm/responders/echo/EchoResponder.java
 create mode 100644 src/main/java/com/lockarhythm/responders/exit/ExitResponder.java
 create mode 100644 src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java
 create mode 100644 src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java

diff --git a/BUILD b/BUILD
index 5f4fa483..dd7185dc 100644
--- a/BUILD
+++ b/BUILD
@@ -3,15 +3,35 @@ load("@rules_java//java:defs.bzl", "java_test")
 
 java_binary(
     name = "Duke",
-    srcs = glob(["src/main/java/com/lockarhythm/cmdline/*.java"]),
+    srcs = glob([
+        "src/main/java/com/lockarhythm/**/*.java",
+    ]),
+    deps = ["@maven//:org_apache_commons_commons_lang3"]
+)
+
+java_test(
+    name = "TestDuke",
+    size = "small",
+    srcs = glob([
+        "src/test/java/com/lockarhythm/**/*.java",
+        "src/main/java/com/lockarhythm/**/*.java",
+    ]),
+)
+
+java_test(
+    name = "TestEchoResponder",
+    size = "small",
+    srcs = glob([
+        "src/test/java/com/lockarhythm/**/*.java",
+        "src/main/java/com/lockarhythm/**/*.java",
+    ]),
 )
 
 java_test(
-    name = "AllTests",
+    name = "TestExitResponder",
     size = "small",
-    test_class = "com.lockarhythm.cmdline.TestDuke",
     srcs = glob([
-        "src/main/java/com/lockarhythm/cmdline/*.java",
-        "src/test/java/com/lockarhythm/cmdline/*.java",
+        "src/test/java/com/lockarhythm/**/*.java",
+        "src/main/java/com/lockarhythm/**/*.java",
     ]),
 )
diff --git a/WORKSPACE b/WORKSPACE
index e69de29b..9784f207 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -0,0 +1,25 @@
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+RULES_JVM_EXTERNAL_TAG = "4.0"
+RULES_JVM_EXTERNAL_SHA = "31701ad93dbfe544d597dbe62c9a1fdd76d81d8a9150c2bf1ecf928ecdf97169"
+
+http_archive(
+    name = "rules_jvm_external",
+    strip_prefix = "rules_jvm_external-%s" % RULES_JVM_EXTERNAL_TAG,
+    sha256 = RULES_JVM_EXTERNAL_SHA,
+    url = "https://github.com/bazelbuild/rules_jvm_external/archive/%s.zip" % RULES_JVM_EXTERNAL_TAG,
+)
+
+load("@rules_jvm_external//:defs.bzl", "maven_install")
+
+maven_install(
+    artifacts = [
+        #"com.google.guava:guava:21.0",
+        "org.apache.commons:commons-lang3:3.11"
+    ],
+    repositories = [
+        # Private repositories are supported through HTTP Basic auth
+        "https://maven.google.com",
+        "https://repo1.maven.org/maven2",
+    ],
+)
diff --git a/src/main/java/com/lockarhythm/cmdline/Duke.java b/src/main/java/com/lockarhythm/cmdline/Duke.java
index 06051852..5b18a54e 100644
--- a/src/main/java/com/lockarhythm/cmdline/Duke.java
+++ b/src/main/java/com/lockarhythm/cmdline/Duke.java
@@ -1,13 +1,58 @@
 package com.lockarhythm.cmdline;
 
+import java.util.Scanner;
+import java.util.Arrays;
+
+import com.lockarhythm.responders.QueryRespondable;
+import com.lockarhythm.responders.Response;
+import com.lockarhythm.responders.echo.EchoResponder;
+import com.lockarhythm.responders.exit.ExitResponder;
+
 public class Duke {
-    static String logo =   " ____        _        \n"
-                         + "|  _ \\ _   _| | _____ \n"
-                         + "| | | | | | | |/ / _ \\\n"
-                         + "| |_| | |_| |   <  __/\n"
-                         + "|____/ \\__,_|_|\\_\\___|\n";
+    static String logo =   " \t____        _        \n"
+                           + "\t|  _ \\ _   _| | _____ \n"
+                           + "\t| | | | | | | |/ / _ \\\n"
+                           + "\t| |_| | |_| |   <  __/\n"
+                           + "\t|____/ \\__,_|_|\\_\\___|\n";
+
+    static QueryRespondable[] responders = {
+        new ExitResponder(),
+        new EchoResponder(),
+    };
+
+    private static void print(String ...strings) {
+        System.out.println("\t____________________________________________________________");
+        for (String s : strings) {
+            System.out.println("\t"+s);
+        }
+        System.out.println("\t____________________________________________________________\n");
+    }
+
+    private static Response getResponse(String query) {
+        Response res = null;
+        for (QueryRespondable responder : responders) {
+            res = responder.respondTo(query);
+            if (res != null) {
+                return res;
+            }
+        }
+        return res;
+    }
 
     public static void main(String[] args) {
-        System.out.println("Hello from\n" + logo);
+        String line;
+        Scanner in = new Scanner(System.in);
+
+        print("Hello I'm\n" + logo, "What can I do for you?");
+
+        line = in.nextLine();
+        Response res = getResponse(line);
+        while(!res.shouldExit()) {
+            print(line);
+            line = in.nextLine();
+            res = getResponse(line);
+        }
+
+        print(res.getText());
     }
 }
diff --git a/src/main/java/com/lockarhythm/responders/QueryRespondable.java b/src/main/java/com/lockarhythm/responders/QueryRespondable.java
new file mode 100644
index 00000000..2501b113
--- /dev/null
+++ b/src/main/java/com/lockarhythm/responders/QueryRespondable.java
@@ -0,0 +1,5 @@
+package com.lockarhythm.responders;
+
+public interface QueryRespondable {
+  Response respondTo(String query);
+}
diff --git a/src/main/java/com/lockarhythm/responders/Response.java b/src/main/java/com/lockarhythm/responders/Response.java
new file mode 100644
index 00000000..c9a7f9c2
--- /dev/null
+++ b/src/main/java/com/lockarhythm/responders/Response.java
@@ -0,0 +1,19 @@
+package com.lockarhythm.responders;
+
+public class Response {
+  private String text;
+  private boolean shouldExit;
+
+  public Response(String text, boolean shouldExit) {
+    this.text = text;
+    this.shouldExit = shouldExit;
+  }
+
+  public String getText() {
+    return text;
+  }
+
+  public boolean shouldExit() {
+    return shouldExit;
+  }
+}
diff --git a/src/main/java/com/lockarhythm/responders/echo/EchoResponder.java b/src/main/java/com/lockarhythm/responders/echo/EchoResponder.java
new file mode 100644
index 00000000..7547ba76
--- /dev/null
+++ b/src/main/java/com/lockarhythm/responders/echo/EchoResponder.java
@@ -0,0 +1,10 @@
+package com.lockarhythm.responders.echo;
+
+import com.lockarhythm.responders.Response;
+import com.lockarhythm.responders.QueryRespondable;
+
+public class EchoResponder implements QueryRespondable {
+    public Response respondTo(String query) {
+        return new Response(query, false);
+    }
+}
diff --git a/src/main/java/com/lockarhythm/responders/exit/ExitResponder.java b/src/main/java/com/lockarhythm/responders/exit/ExitResponder.java
new file mode 100644
index 00000000..34a1bb32
--- /dev/null
+++ b/src/main/java/com/lockarhythm/responders/exit/ExitResponder.java
@@ -0,0 +1,13 @@
+package com.lockarhythm.responders.exit;
+
+import com.lockarhythm.responders.Response;
+import com.lockarhythm.responders.QueryRespondable;
+
+public class ExitResponder implements QueryRespondable {
+    public Response respondTo(String query) {
+        if (query.equals("bye")) {
+            return new Response("Bye. Hope to see you again soon!", true);
+        }
+        return null;
+    }
+}
diff --git a/src/test/java/com/lockarhythm/cmdline/TestDuke.java b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
index 2a0d9a5b..65c8d826 100644
--- a/src/test/java/com/lockarhythm/cmdline/TestDuke.java
+++ b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
@@ -1,22 +1,39 @@
 package com.lockarhythm.cmdline;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 import org.junit.Test;
 
 import java.io.ByteArrayOutputStream;
+import java.io.ByteArrayInputStream;
 import java.io.PrintStream;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Paths;
 
 public class TestDuke {
     private final PrintStream standardOut = System.out;
+    private final InputStream standardIn = System.in;
     private final ByteArrayOutputStream out = new ByteArrayOutputStream();
+    private final ByteArrayInputStream in = new ByteArrayInputStream(
+        "list\nblah\nbye".getBytes()
+    );
 
     @Test
-    public void testNoArgument() throws Exception {
+    public void testMeetsLevel1() throws Exception {
+        System.setIn(in);
         System.setOut(new PrintStream(out));
+
         Duke.main(null);
-        assertEquals(("Hello from\n"+Duke.logo).trim(), out.toString().trim());
+        String output = out.toString().trim();
+        assertFalse(output.isEmpty());
+
+        assertTrue("it greets the user", output.contains("Hello"));
+        assertTrue("it echos the command back", output.contains("blah"));
+        assertTrue("it exits", output.contains("Bye. Hope to see you again soon!"));
+
         System.setOut(standardOut);
+        System.setIn(standardIn);
     }
 
 }
diff --git a/src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java b/src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java
new file mode 100644
index 00000000..e883f6f8
--- /dev/null
+++ b/src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java
@@ -0,0 +1,18 @@
+package com.lockarhythm.responders.echo;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+import com.lockarhythm.responders.Response;
+
+public class TestEchoResponder {
+    @Test
+    public void testEchosBackText() throws Exception {
+        EchoResponder responder = new EchoResponder();
+        Response res = responder.respondTo("hello");
+
+        assertEquals("hello", res.getText());
+        assertFalse(res.shouldExit());
+    }
+}
diff --git a/src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java b/src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java
new file mode 100644
index 00000000..f2007459
--- /dev/null
+++ b/src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java
@@ -0,0 +1,25 @@
+package com.lockarhythm.responders.exit;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+import com.lockarhythm.responders.Response;
+
+public class TestExitResponder {
+    @Test
+    public void testExitsOnKeyword() throws Exception {
+        ExitResponder responder = new ExitResponder();
+        Response res = responder.respondTo("bye");
+
+        assertTrue(res.shouldExit());
+    }
+
+    @Test
+    public void testNullOnNonkeyword() throws Exception {
+        ExitResponder responder = new ExitResponder();
+        Response res = responder.respondTo("hello");
+
+        assertNull(res);
+    }
+}

From e15de968beb734f4ca2f125e4b718e80b6dbd4b1 Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Fri, 20 Aug 2021 22:30:53 +0800
Subject: [PATCH 06/32] Fix bug -- should return response text.

---
 src/main/java/com/lockarhythm/cmdline/Duke.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/com/lockarhythm/cmdline/Duke.java b/src/main/java/com/lockarhythm/cmdline/Duke.java
index 5b18a54e..51dd5dee 100644
--- a/src/main/java/com/lockarhythm/cmdline/Duke.java
+++ b/src/main/java/com/lockarhythm/cmdline/Duke.java
@@ -48,7 +48,7 @@ public static void main(String[] args) {
         line = in.nextLine();
         Response res = getResponse(line);
         while(!res.shouldExit()) {
-            print(line);
+            print(res.getText());
             line = in.nextLine();
             res = getResponse(line);
         }

From 67cbff0657b9175a3f991b05f7fd8210d9468568 Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Fri, 20 Aug 2021 22:28:50 +0800
Subject: [PATCH 07/32] Implement level 2 -- Add, List.

---
 BUILD                                         |  9 +++++
 .../java/com/lockarhythm/cmdline/Duke.java    |  7 ++--
 .../responders/addlist/AddListResponder.java  | 31 +++++++++++++++++
 .../com/lockarhythm/cmdline/TestDuke.java     | 10 +++---
 .../addlist/TestAddListResponder.java         | 33 +++++++++++++++++++
 5 files changed, 83 insertions(+), 7 deletions(-)
 create mode 100644 src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
 create mode 100644 src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java

diff --git a/BUILD b/BUILD
index dd7185dc..ab7919a6 100644
--- a/BUILD
+++ b/BUILD
@@ -35,3 +35,12 @@ java_test(
         "src/main/java/com/lockarhythm/**/*.java",
     ]),
 )
+
+java_test(
+    name = "TestAddListResponder",
+    size = "small",
+    srcs = glob([
+        "src/test/java/com/lockarhythm/**/*.java",
+        "src/main/java/com/lockarhythm/**/*.java",
+    ]),
+)
diff --git a/src/main/java/com/lockarhythm/cmdline/Duke.java b/src/main/java/com/lockarhythm/cmdline/Duke.java
index 51dd5dee..c3925a29 100644
--- a/src/main/java/com/lockarhythm/cmdline/Duke.java
+++ b/src/main/java/com/lockarhythm/cmdline/Duke.java
@@ -5,8 +5,8 @@
 
 import com.lockarhythm.responders.QueryRespondable;
 import com.lockarhythm.responders.Response;
-import com.lockarhythm.responders.echo.EchoResponder;
 import com.lockarhythm.responders.exit.ExitResponder;
+import com.lockarhythm.responders.addlist.AddListResponder;
 
 public class Duke {
     static String logo =   " \t____        _        \n"
@@ -17,13 +17,14 @@ public class Duke {
 
     static QueryRespondable[] responders = {
         new ExitResponder(),
-        new EchoResponder(),
+        new AddListResponder(),
     };
 
     private static void print(String ...strings) {
         System.out.println("\t____________________________________________________________");
         for (String s : strings) {
-            System.out.println("\t"+s);
+            s = Arrays.stream(s.split("\n")).map(x -> "\t" + x).reduce("", (x, y) -> x + y + "\n");
+            System.out.println(s);
         }
         System.out.println("\t____________________________________________________________\n");
     }
diff --git a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
new file mode 100644
index 00000000..6bbd501c
--- /dev/null
+++ b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
@@ -0,0 +1,31 @@
+package com.lockarhythm.responders.addlist;
+
+import com.lockarhythm.responders.Response;
+import com.lockarhythm.responders.QueryRespondable;
+
+import java.util.ArrayList;
+
+public class AddListResponder implements QueryRespondable {
+    private ArrayList<String> list;
+
+    public AddListResponder() {
+        list = new ArrayList<String>();
+    }
+
+    public Response respondTo(String query) {
+        if (query.equals("list")) {
+            StringBuilder s = new StringBuilder();
+            int i = 1;
+            for (i = 0; i < list.size(); i++) {
+                s.append(i+1);
+                s.append(". ");
+                s.append(list.get(i));
+                s.append("\n");
+            }
+            return new Response(s.toString(), false);
+        }
+        // by default, adds the given query.
+        list.add(query);
+        return new Response("added: " + query, false);
+    }
+}
diff --git a/src/test/java/com/lockarhythm/cmdline/TestDuke.java b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
index 65c8d826..6a11ef76 100644
--- a/src/test/java/com/lockarhythm/cmdline/TestDuke.java
+++ b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
@@ -16,11 +16,11 @@ public class TestDuke {
     private final InputStream standardIn = System.in;
     private final ByteArrayOutputStream out = new ByteArrayOutputStream();
     private final ByteArrayInputStream in = new ByteArrayInputStream(
-        "list\nblah\nbye".getBytes()
+        "read book\nreturn book\nlist\nbye".getBytes()
     );
 
     @Test
-    public void testMeetsLevel1() throws Exception {
+    public void testMeetsLevel2() throws Exception {
         System.setIn(in);
         System.setOut(new PrintStream(out));
 
@@ -28,8 +28,10 @@ public void testMeetsLevel1() throws Exception {
         String output = out.toString().trim();
         assertFalse(output.isEmpty());
 
-        assertTrue("it greets the user", output.contains("Hello"));
-        assertTrue("it echos the command back", output.contains("blah"));
+        assertTrue("it adds the 1st item", output.contains("added: read book"));
+        assertTrue("it adds the 2nd item", output.contains("added: return book"));
+        assertTrue("it lists the items", output.contains("1. read book"));
+        assertTrue("it lists the items", output.contains("2. return book"));
         assertTrue("it exits", output.contains("Bye. Hope to see you again soon!"));
 
         System.setOut(standardOut);
diff --git a/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java b/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
new file mode 100644
index 00000000..c57f7195
--- /dev/null
+++ b/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
@@ -0,0 +1,33 @@
+package com.lockarhythm.responders.addlist;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+import com.lockarhythm.responders.Response;
+
+public class TestAddListResponder {
+    @Test
+    public void testAddsItemsAndLists() throws Exception {
+        AddListResponder responder = new AddListResponder();
+
+        Response res = responder.respondTo("read book");
+        assertEquals("added: read book", res.getText());
+
+        res = responder.respondTo("return book");
+        assertEquals("added: return book", res.getText());
+
+        res = responder.respondTo("list");
+        assertEquals("1. read book\n2. return book\n", res.getText());
+
+    }
+
+    @Test
+    public void testEmptyList() throws Exception {
+        AddListResponder responder = new AddListResponder();
+
+        Response res = responder.respondTo("list");
+        assertEquals("", res.getText());
+
+    }
+}

From 7321f72ab8425cb1c43d4d7592e2c6b1e96d96b5 Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Fri, 20 Aug 2021 23:54:48 +0800
Subject: [PATCH 08/32] Refactor into separate method.

---
 .../responders/addlist/AddListResponder.java   | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
index 6bbd501c..20ffe009 100644
--- a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
+++ b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
@@ -12,16 +12,20 @@ public AddListResponder() {
         list = new ArrayList<String>();
     }
 
+    private void printList(StringBuilder s) {
+        int i = 1;
+        for (i = 0; i < list.size(); i++) {
+            s.append(i+1);
+            s.append(". ");
+            s.append(list.get(i));
+            s.append("\n");
+        }
+    }
+
     public Response respondTo(String query) {
         if (query.equals("list")) {
             StringBuilder s = new StringBuilder();
-            int i = 1;
-            for (i = 0; i < list.size(); i++) {
-                s.append(i+1);
-                s.append(". ");
-                s.append(list.get(i));
-                s.append("\n");
-            }
+            printList(s);
             return new Response(s.toString(), false);
         }
         // by default, adds the given query.

From 8545772e149f721dba869b6b38fb3657f90a7359 Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Sat, 21 Aug 2021 08:01:34 +0800
Subject: [PATCH 09/32] Implements Level-3: Mark as Done

---
 BUILD                                         | 18 +++++++++
 .../responders/addlist/AddListResponder.java  | 37 +++++++++++-------
 src/main/java/com/lockarhythm/tasks/Task.java | 34 +++++++++++++++++
 .../java/com/lockarhythm/tasks/TaskList.java  | 38 +++++++++++++++++++
 .../com/lockarhythm/cmdline/TestDuke.java     |  4 +-
 .../addlist/TestAddListResponder.java         | 36 ++++++++++++++++--
 .../java/com/lockarhythm/tasks/TestTask.java  | 15 ++++++++
 .../com/lockarhythm/tasks/TestTaskList.java   | 19 ++++++++++
 8 files changed, 182 insertions(+), 19 deletions(-)
 create mode 100644 src/main/java/com/lockarhythm/tasks/Task.java
 create mode 100644 src/main/java/com/lockarhythm/tasks/TaskList.java
 create mode 100644 src/test/java/com/lockarhythm/tasks/TestTask.java
 create mode 100644 src/test/java/com/lockarhythm/tasks/TestTaskList.java

diff --git a/BUILD b/BUILD
index ab7919a6..86e028ee 100644
--- a/BUILD
+++ b/BUILD
@@ -44,3 +44,21 @@ java_test(
         "src/main/java/com/lockarhythm/**/*.java",
     ]),
 )
+
+java_test(
+    name = "TestTask",
+    size = "small",
+    srcs = glob([
+        "src/test/java/com/lockarhythm/**/*.java",
+        "src/main/java/com/lockarhythm/**/*.java",
+    ]),
+)
+
+java_test(
+    name = "TestTaskList",
+    size = "small",
+    srcs = glob([
+        "src/test/java/com/lockarhythm/**/*.java",
+        "src/main/java/com/lockarhythm/**/*.java",
+    ]),
+)
diff --git a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
index 20ffe009..efa4db0e 100644
--- a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
+++ b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
@@ -1,32 +1,43 @@
 package com.lockarhythm.responders.addlist;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
 import com.lockarhythm.responders.Response;
 import com.lockarhythm.responders.QueryRespondable;
 
-import java.util.ArrayList;
+import com.lockarhythm.tasks.TaskList;
+import com.lockarhythm.tasks.Task;
 
 public class AddListResponder implements QueryRespondable {
-    private ArrayList<String> list;
+    private static String doneCommandPrefix = "done ";
+    private TaskList list;
+    Pattern pattern = Pattern.compile(doneCommandPrefix+"(\\d+)");
 
     public AddListResponder() {
-        list = new ArrayList<String>();
+        list = new TaskList();
+    }
+
+    private boolean isDoneCommand(Matcher matcher) {
+        return matcher.find();
     }
 
-    private void printList(StringBuilder s) {
-        int i = 1;
-        for (i = 0; i < list.size(); i++) {
-            s.append(i+1);
-            s.append(". ");
-            s.append(list.get(i));
-            s.append("\n");
+    private Response handleDoneCommand(Matcher matcher) {
+        int i = Integer.parseInt(matcher.group(1));
+        if (i > 0 && i <= list.size()) {
+            Task task = list.markAsDone(i - 1);
+            return new Response("Nice! I've marked this task as done:\n\t" + task.toString(), false);
         }
+        return new Response(String.format("Item %d is not on the list. I cannot mark it as done!", i), false);
     }
 
     public Response respondTo(String query) {
         if (query.equals("list")) {
-            StringBuilder s = new StringBuilder();
-            printList(s);
-            return new Response(s.toString(), false);
+            return new Response("Here are the tasks in your list:\n"+list.toString(), false);
+        }
+        Matcher matcher = pattern.matcher(query);
+        if (isDoneCommand(matcher)) {
+            return handleDoneCommand(matcher);
         }
         // by default, adds the given query.
         list.add(query);
diff --git a/src/main/java/com/lockarhythm/tasks/Task.java b/src/main/java/com/lockarhythm/tasks/Task.java
new file mode 100644
index 00000000..1230cbdd
--- /dev/null
+++ b/src/main/java/com/lockarhythm/tasks/Task.java
@@ -0,0 +1,34 @@
+package com.lockarhythm.tasks;
+
+import java.util.ArrayList;
+
+public class Task {
+    private String description;
+    private boolean isDone;
+
+    public Task(String description) {
+        this.description = description;
+        this.isDone = false;
+    }
+
+    public void toggleDone() {
+        this.isDone = !this.isDone;
+    }
+
+    public String getDescription() {
+      return description;
+    }
+
+    public boolean isDone() {
+      return isDone;
+    }
+
+    private String getDoneIcon() {
+      return isDone ? "X" : " ";
+    }
+
+    @Override
+    public String toString() {
+        return String.format("[%s] %s", getDoneIcon(), description);
+    }
+}
diff --git a/src/main/java/com/lockarhythm/tasks/TaskList.java b/src/main/java/com/lockarhythm/tasks/TaskList.java
new file mode 100644
index 00000000..2f514aa0
--- /dev/null
+++ b/src/main/java/com/lockarhythm/tasks/TaskList.java
@@ -0,0 +1,38 @@
+package com.lockarhythm.tasks;
+
+import java.util.ArrayList;
+
+public class TaskList {
+    private ArrayList<Task> list;
+
+    public TaskList() {
+        list = new ArrayList<Task>();
+    }
+
+    public int size() {
+        return list.size();
+    }
+
+    public void add(String description) {
+        list.add(new Task(description));
+    }
+
+    public Task markAsDone(int index) {
+        Task t = list.get(index);
+        t.toggleDone();
+        return t;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder s = new StringBuilder();
+        int i = 1;
+        for (i = 0; i < list.size(); i++) {
+            s.append(i+1);
+            s.append(".");
+            s.append(list.get(i));
+            s.append("\n");
+        }
+        return s.toString();
+    }
+}
diff --git a/src/test/java/com/lockarhythm/cmdline/TestDuke.java b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
index 6a11ef76..9a291299 100644
--- a/src/test/java/com/lockarhythm/cmdline/TestDuke.java
+++ b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
@@ -30,8 +30,8 @@ public void testMeetsLevel2() throws Exception {
 
         assertTrue("it adds the 1st item", output.contains("added: read book"));
         assertTrue("it adds the 2nd item", output.contains("added: return book"));
-        assertTrue("it lists the items", output.contains("1. read book"));
-        assertTrue("it lists the items", output.contains("2. return book"));
+        assertTrue("it lists the items", output.contains("1.[ ] read book"));
+        assertTrue("it lists the items", output.contains("2.[ ] return book"));
         assertTrue("it exits", output.contains("Bye. Hope to see you again soon!"));
 
         System.setOut(standardOut);
diff --git a/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java b/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
index c57f7195..eb89e15d 100644
--- a/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
+++ b/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
@@ -18,16 +18,44 @@ public void testAddsItemsAndLists() throws Exception {
         assertEquals("added: return book", res.getText());
 
         res = responder.respondTo("list");
-        assertEquals("1. read book\n2. return book\n", res.getText());
+        assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
 
     }
 
     @Test
-    public void testEmptyList() throws Exception {
+    public void testMarkAsDoneHappyPath() throws Exception {
         AddListResponder responder = new AddListResponder();
 
-        Response res = responder.respondTo("list");
-        assertEquals("", res.getText());
+        Response res = responder.respondTo("read book");
+        assertEquals("added: read book", res.getText());
+
+        res = responder.respondTo("return book");
+        assertEquals("added: return book", res.getText());
+
+        res = responder.respondTo("done 1");
+        assertTrue(res.getText().contains("Nice! I've marked this task as done"));
+        assertTrue(res.getText().contains("read book"));
+
+        res = responder.respondTo("list");
+        assertTrue(res.getText().contains("1.[X] read book\n2.[ ] return book\n"));
+
+    }
+
+    @Test
+    public void testMarkAsDoneOnNonExistentItem() throws Exception {
+        AddListResponder responder = new AddListResponder();
+
+        Response res = responder.respondTo("read book");
+        assertEquals("added: read book", res.getText());
+
+        res = responder.respondTo("return book");
+        assertEquals("added: return book", res.getText());
+
+        res = responder.respondTo("done 10000");
+        assertTrue(res.getText().contains("Item 10000 is not on the list. I cannot mark it as done!"));
+
+        res = responder.respondTo("list");
+        assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
 
     }
 }
diff --git a/src/test/java/com/lockarhythm/tasks/TestTask.java b/src/test/java/com/lockarhythm/tasks/TestTask.java
new file mode 100644
index 00000000..87a3ed5d
--- /dev/null
+++ b/src/test/java/com/lockarhythm/tasks/TestTask.java
@@ -0,0 +1,15 @@
+package com.lockarhythm.tasks;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+public class TestTask {
+    @Test
+    public void testToggleDone() throws Exception {
+        Task task = new Task("learn java well");
+
+        task.toggleDone();
+        assertTrue("task should be done", task.isDone());
+    }
+}
diff --git a/src/test/java/com/lockarhythm/tasks/TestTaskList.java b/src/test/java/com/lockarhythm/tasks/TestTaskList.java
new file mode 100644
index 00000000..5baa9133
--- /dev/null
+++ b/src/test/java/com/lockarhythm/tasks/TestTaskList.java
@@ -0,0 +1,19 @@
+package com.lockarhythm.tasks;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+public class TestTaskList {
+    @Test
+    public void testAddTask() throws Exception {
+        TaskList list = new TaskList();
+
+        list.add("learn useful libraries in java");
+        list.add("learn bazel");
+        assertEquals("has correct number of items", 2, list.size());
+
+        Task task = list.markAsDone(1);
+        assertEquals("can mark tasks as done", "learn bazel", task.getDescription());
+    }
+}

From 9aa137f3a8f2444f4c9ebeadf5d40ea1a39d8498 Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Sat, 21 Aug 2021 22:22:06 +0800
Subject: [PATCH 10/32] Refactor markasdone as separate responder.

---
 BUILD                                         |  9 ++++
 .../java/com/lockarhythm/cmdline/Duke.java    |  7 ++-
 .../responders/addlist/AddListResponder.java  | 24 +--------
 .../markasdone/MarkAsDoneResponder.java       | 33 ++++++++++++
 .../addlist/TestAddListResponder.java         | 40 +-------------
 .../markasdone/TestMarkAsDoneResponder.java   | 52 +++++++++++++++++++
 6 files changed, 104 insertions(+), 61 deletions(-)
 create mode 100644 src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
 create mode 100644 src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java

diff --git a/BUILD b/BUILD
index 86e028ee..ea4e71a8 100644
--- a/BUILD
+++ b/BUILD
@@ -45,6 +45,15 @@ java_test(
     ]),
 )
 
+java_test(
+    name = "TestMarkAsDoneResponder",
+    size = "small",
+    srcs = glob([
+        "src/test/java/com/lockarhythm/**/*.java",
+        "src/main/java/com/lockarhythm/**/*.java",
+    ]),
+)
+
 java_test(
     name = "TestTask",
     size = "small",
diff --git a/src/main/java/com/lockarhythm/cmdline/Duke.java b/src/main/java/com/lockarhythm/cmdline/Duke.java
index c3925a29..63a50e3e 100644
--- a/src/main/java/com/lockarhythm/cmdline/Duke.java
+++ b/src/main/java/com/lockarhythm/cmdline/Duke.java
@@ -7,6 +7,8 @@
 import com.lockarhythm.responders.Response;
 import com.lockarhythm.responders.exit.ExitResponder;
 import com.lockarhythm.responders.addlist.AddListResponder;
+import com.lockarhythm.responders.markasdone.MarkAsDoneResponder;
+import com.lockarhythm.tasks.TaskList;
 
 public class Duke {
     static String logo =   " \t____        _        \n"
@@ -15,9 +17,12 @@ public class Duke {
                            + "\t| |_| | |_| |   <  __/\n"
                            + "\t|____/ \\__,_|_|\\_\\___|\n";
 
+    static TaskList list = new TaskList();
+
     static QueryRespondable[] responders = {
         new ExitResponder(),
-        new AddListResponder(),
+        new MarkAsDoneResponder(list),
+        new AddListResponder(list),
     };
 
     private static void print(String ...strings) {
diff --git a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
index efa4db0e..7205d87f 100644
--- a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
+++ b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
@@ -7,38 +7,18 @@
 import com.lockarhythm.responders.QueryRespondable;
 
 import com.lockarhythm.tasks.TaskList;
-import com.lockarhythm.tasks.Task;
 
 public class AddListResponder implements QueryRespondable {
-    private static String doneCommandPrefix = "done ";
     private TaskList list;
-    Pattern pattern = Pattern.compile(doneCommandPrefix+"(\\d+)");
 
-    public AddListResponder() {
-        list = new TaskList();
-    }
-
-    private boolean isDoneCommand(Matcher matcher) {
-        return matcher.find();
-    }
-
-    private Response handleDoneCommand(Matcher matcher) {
-        int i = Integer.parseInt(matcher.group(1));
-        if (i > 0 && i <= list.size()) {
-            Task task = list.markAsDone(i - 1);
-            return new Response("Nice! I've marked this task as done:\n\t" + task.toString(), false);
-        }
-        return new Response(String.format("Item %d is not on the list. I cannot mark it as done!", i), false);
+    public AddListResponder(TaskList list) {
+        this.list = list;
     }
 
     public Response respondTo(String query) {
         if (query.equals("list")) {
             return new Response("Here are the tasks in your list:\n"+list.toString(), false);
         }
-        Matcher matcher = pattern.matcher(query);
-        if (isDoneCommand(matcher)) {
-            return handleDoneCommand(matcher);
-        }
         // by default, adds the given query.
         list.add(query);
         return new Response("added: " + query, false);
diff --git a/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java b/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
new file mode 100644
index 00000000..c7d66246
--- /dev/null
+++ b/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
@@ -0,0 +1,33 @@
+package com.lockarhythm.responders.markasdone;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import com.lockarhythm.responders.Response;
+import com.lockarhythm.responders.QueryRespondable;
+
+import com.lockarhythm.tasks.TaskList;
+import com.lockarhythm.tasks.Task;
+
+public class MarkAsDoneResponder implements QueryRespondable {
+    private static String doneCommandPrefix = "done ";
+    private TaskList list;
+    Pattern pattern = Pattern.compile(doneCommandPrefix+"(\\d+)");
+
+    public MarkAsDoneResponder(TaskList list) {
+        this.list = list;
+    }
+
+    public Response respondTo(String query) {
+        Matcher matcher = pattern.matcher(query);
+        if (matcher.find()) {
+            int i = Integer.parseInt(matcher.group(1));
+            if (i > 0 && i <= list.size()) {
+                Task task = list.markAsDone(i - 1);
+                return new Response("Nice! I've marked this task as done:\n\t" + task.toString(), false);
+            }
+            return new Response(String.format("Item %d is not on the list. I cannot mark it as done!", i), false);
+        }
+        return null;
+    }
+}
diff --git a/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java b/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
index eb89e15d..306f6f64 100644
--- a/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
+++ b/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
@@ -5,11 +5,12 @@
 import org.junit.Test;
 
 import com.lockarhythm.responders.Response;
+import com.lockarhythm.tasks.TaskList;
 
 public class TestAddListResponder {
     @Test
     public void testAddsItemsAndLists() throws Exception {
-        AddListResponder responder = new AddListResponder();
+        AddListResponder responder = new AddListResponder(new TaskList());
 
         Response res = responder.respondTo("read book");
         assertEquals("added: read book", res.getText());
@@ -21,41 +22,4 @@ public void testAddsItemsAndLists() throws Exception {
         assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
 
     }
-
-    @Test
-    public void testMarkAsDoneHappyPath() throws Exception {
-        AddListResponder responder = new AddListResponder();
-
-        Response res = responder.respondTo("read book");
-        assertEquals("added: read book", res.getText());
-
-        res = responder.respondTo("return book");
-        assertEquals("added: return book", res.getText());
-
-        res = responder.respondTo("done 1");
-        assertTrue(res.getText().contains("Nice! I've marked this task as done"));
-        assertTrue(res.getText().contains("read book"));
-
-        res = responder.respondTo("list");
-        assertTrue(res.getText().contains("1.[X] read book\n2.[ ] return book\n"));
-
-    }
-
-    @Test
-    public void testMarkAsDoneOnNonExistentItem() throws Exception {
-        AddListResponder responder = new AddListResponder();
-
-        Response res = responder.respondTo("read book");
-        assertEquals("added: read book", res.getText());
-
-        res = responder.respondTo("return book");
-        assertEquals("added: return book", res.getText());
-
-        res = responder.respondTo("done 10000");
-        assertTrue(res.getText().contains("Item 10000 is not on the list. I cannot mark it as done!"));
-
-        res = responder.respondTo("list");
-        assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
-
-    }
 }
diff --git a/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java b/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java
new file mode 100644
index 00000000..b4c51647
--- /dev/null
+++ b/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java
@@ -0,0 +1,52 @@
+package com.lockarhythm.responders.markasdone;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+import com.lockarhythm.responders.Response;
+import com.lockarhythm.responders.addlist.AddListResponder;
+import com.lockarhythm.tasks.TaskList;
+
+public class TestMarkAsDoneResponder {
+    @Test
+    public void testMarkAsDoneHappyPath() throws Exception {
+        TaskList list = new TaskList();
+        MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
+        AddListResponder alresponder = new AddListResponder(list);
+
+        Response res = alresponder.respondTo("read book");
+        assertEquals("added: read book", res.getText());
+
+        res = alresponder.respondTo("return book");
+        assertEquals("added: return book", res.getText());
+
+        res = mdresponder.respondTo("done 1");
+        assertTrue(res.getText().contains("Nice! I've marked this task as done"));
+        assertTrue(res.getText().contains("read book"));
+
+        res = alresponder.respondTo("list");
+        assertTrue(res.getText().contains("1.[X] read book\n2.[ ] return book\n"));
+
+    }
+
+    @Test
+    public void testMarkAsDoneOnNonExistentItem() throws Exception {
+        TaskList list = new TaskList();
+        MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
+        AddListResponder alresponder = new AddListResponder(list);
+
+        Response res = alresponder.respondTo("read book");
+        assertEquals("added: read book", res.getText());
+
+        res = alresponder.respondTo("return book");
+        assertEquals("added: return book", res.getText());
+
+        res = mdresponder.respondTo("done 10000");
+        assertTrue(res.getText().contains("Item 10000 is not on the list. I cannot mark it as done!"));
+
+        res = alresponder.respondTo("list");
+        assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
+
+    }
+}

From f6069de566bbaa4f417a8aeba1d726a133d14605 Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Mon, 23 Aug 2021 01:55:56 +0800
Subject: [PATCH 11/32] Refactor BUILD file.

---
 BUILD | 84 ++++++++++++++---------------------------------------------
 1 file changed, 20 insertions(+), 64 deletions(-)

diff --git a/BUILD b/BUILD
index ea4e71a8..ac1cceed 100644
--- a/BUILD
+++ b/BUILD
@@ -1,5 +1,4 @@
-load("@rules_java//java:defs.bzl", "java_binary")
-load("@rules_java//java:defs.bzl", "java_test")
+load("@rules_java//java:defs.bzl", "java_binary", "java_test")
 
 java_binary(
     name = "Duke",
@@ -9,65 +8,22 @@ java_binary(
     deps = ["@maven//:org_apache_commons_commons_lang3"]
 )
 
-java_test(
-    name = "TestDuke",
-    size = "small",
-    srcs = glob([
-        "src/test/java/com/lockarhythm/**/*.java",
-        "src/main/java/com/lockarhythm/**/*.java",
-    ]),
-)
-
-java_test(
-    name = "TestEchoResponder",
-    size = "small",
-    srcs = glob([
-        "src/test/java/com/lockarhythm/**/*.java",
-        "src/main/java/com/lockarhythm/**/*.java",
-    ]),
-)
-
-java_test(
-    name = "TestExitResponder",
-    size = "small",
-    srcs = glob([
-        "src/test/java/com/lockarhythm/**/*.java",
-        "src/main/java/com/lockarhythm/**/*.java",
-    ]),
-)
-
-java_test(
-    name = "TestAddListResponder",
-    size = "small",
-    srcs = glob([
-        "src/test/java/com/lockarhythm/**/*.java",
-        "src/main/java/com/lockarhythm/**/*.java",
-    ]),
-)
-
-java_test(
-    name = "TestMarkAsDoneResponder",
-    size = "small",
-    srcs = glob([
-        "src/test/java/com/lockarhythm/**/*.java",
-        "src/main/java/com/lockarhythm/**/*.java",
-    ]),
-)
-
-java_test(
-    name = "TestTask",
-    size = "small",
-    srcs = glob([
-        "src/test/java/com/lockarhythm/**/*.java",
-        "src/main/java/com/lockarhythm/**/*.java",
-    ]),
-)
-
-java_test(
-    name = "TestTaskList",
-    size = "small",
-    srcs = glob([
-        "src/test/java/com/lockarhythm/**/*.java",
-        "src/main/java/com/lockarhythm/**/*.java",
-    ]),
-)
+[
+  java_test(
+      name = class_name,
+      size = "small",
+      srcs = glob([
+          "src/test/java/com/lockarhythm/**/*.java",
+          "src/main/java/com/lockarhythm/**/*.java",
+      ]),
+  )
+  for class_name in [
+      "TestDuke",
+      "TestEchoResponder",
+      "TestExitResponder",
+      "TestAddListResponder",
+      "TestMarkAsDoneResponder",
+      "TestTask",
+      "TestTaskList",
+  ]
+]

From 85c0c594f39e4fa2f57092d06ec6320a6e24a5a0 Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Mon, 23 Aug 2021 22:03:03 +0800
Subject: [PATCH 12/32] Implement A-TextUiTesting for macOS and bazel.

---
 text-ui-test/EXPECTED.TXT | 57 ++++++++++++++++++++++++++++++++++-----
 text-ui-test/input.txt    |  7 +++++
 text-ui-test/runtest.sh   |  6 ++---
 3 files changed, 61 insertions(+), 9 deletions(-)
 mode change 100644 => 100755 text-ui-test/runtest.sh

diff --git a/text-ui-test/EXPECTED.TXT b/text-ui-test/EXPECTED.TXT
index 657e74f6..69bbc0bb 100644
--- a/text-ui-test/EXPECTED.TXT
+++ b/text-ui-test/EXPECTED.TXT
@@ -1,7 +1,52 @@
-Hello from
- ____        _        
-|  _ \ _   _| | _____ 
-| | | | | | | |/ / _ \
-| |_| | |_| |   <  __/
-|____/ \__,_|_|\_\___|
+	____________________________________________________________
+	Hello I'm
+	 	____        _        
+		|  _ \ _   _| | _____ 
+		| | | | | | | |/ / _ \
+		| |_| | |_| |   <  __/
+		|____/ \__,_|_|\_\___|
+
+	What can I do for you?
+
+	____________________________________________________________
+
+	____________________________________________________________
+	added: read book
+
+	____________________________________________________________
+
+	____________________________________________________________
+	added: return book
+
+	____________________________________________________________
+
+	____________________________________________________________
+	added: buy bread
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Nice! I've marked this task as done:
+		[X] read book
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Here are the tasks in your list:
+	1.[X] read book
+	2.[ ] return book
+	3.[ ] buy bread
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Nice! I've marked this task as done:
+		[X] return book
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Bye. Hope to see you again soon!
+
+	____________________________________________________________
 
diff --git a/text-ui-test/input.txt b/text-ui-test/input.txt
index e69de29b..2cb3cf8a 100644
--- a/text-ui-test/input.txt
+++ b/text-ui-test/input.txt
@@ -0,0 +1,7 @@
+read book
+return book
+buy bread
+done 1
+list
+done 2
+bye
diff --git a/text-ui-test/runtest.sh b/text-ui-test/runtest.sh
old mode 100644
new mode 100755
index c9ec8700..220caaa7
--- a/text-ui-test/runtest.sh
+++ b/text-ui-test/runtest.sh
@@ -13,14 +13,14 @@ then
 fi
 
 # compile the code into the bin folder, terminates if error occurred
-if ! javac -cp ../src/main/java -Xlint:none -d ../bin ../src/main/java/*.java
+if ! bazel build //:Duke 
 then
     echo "********** BUILD FAILURE **********"
     exit 1
 fi
 
 # run the program, feed commands from input.txt file and redirect the output to the ACTUAL.TXT
-java -classpath ../bin Duke < input.txt > ACTUAL.TXT
+../bazel-bin/Duke < input.txt > ACTUAL.TXT
 
 # convert to UNIX format
 cp EXPECTED.TXT EXPECTED-UNIX.TXT
@@ -35,4 +35,4 @@ then
 else
     echo "Test result: FAILED"
     exit 1
-fi
\ No newline at end of file
+fi

From 6a850922425bd1361ebea85ab974dd1be154ad1b Mon Sep 17 00:00:00 2001
From: 9y5 <mail.yisheng@gmail.com>
Date: Mon, 23 Aug 2021 22:25:22 +0800
Subject: [PATCH 13/32] Basic github workflow: * Installs bazelisk * Builds JAR
 * Runs unit tests * Upload JAR artifact.

---
 .github/workflows/workflow.yml | 39 ++++++++++++++++++++++++++++
 README.md                      | 47 +++++++++++++++-------------------
 2 files changed, 60 insertions(+), 26 deletions(-)
 create mode 100644 .github/workflows/workflow.yml

diff --git a/.github/workflows/workflow.yml b/.github/workflows/workflow.yml
new file mode 100644
index 00000000..7fc94623
--- /dev/null
+++ b/.github/workflows/workflow.yml
@@ -0,0 +1,39 @@
+on: push
+name: Build, Test and Upload JAR
+jobs:
+  checks:
+    name: Run Unit Tests
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+
+    - name: Mount bazel cache
+      uses: actions/cache@v1
+      with:
+        path: "/home/runner/.cache/bazel"
+        key: bazel
+
+    - name: Install bazelisk
+      run: |
+        curl -LO "https://github.com/bazelbuild/bazelisk/releases/download/v1.1.0/bazelisk-linux-amd64"
+        mkdir -p "${GITHUB_WORKSPACE}/bin/"
+        mv bazelisk-linux-amd64 "${GITHUB_WORKSPACE}/bin/bazel"
+        chmod +x "${GITHUB_WORKSPACE}/bin/bazel"
+
+    - name: Run Unit Tests
+      run: |
+        "${GITHUB_WORKSPACE}/bin/bazel" test //...
+
+    - name: Build JAR File
+      run: |
+        "${GITHUB_WORKSPACE}/bin/bazel" build //:Duke_deploy.jar
+
+    - name: "Move file to non-symlink directory (a workaround for some bug See: https://github.com/actions/upload-artifact/issues/92)"
+      run: |
+       mv ${{ github.workspace }}/bazel-bin/Duke_deploy.jar ${{ github.workspace }}/Duke_deploy.jar
+
+    - name: Upload JAR File
+      uses: actions/upload-artifact@v2
+      with:
+        name: Duke_deploy.jar
+        path: ${{ github.workspace }}/Duke_deploy.jar
diff --git a/README.md b/README.md
index e511e631..31020453 100644
--- a/README.md
+++ b/README.md
@@ -2,37 +2,32 @@
 
 This is a project template for a greenfield Java project. It's named after the Java mascot _Duke_. Given below are instructions on how to use it.
 
-## Local Build
+## Build
 Prerequisites: Have `bazel` installed.
+
+To build for local development on macOS:
 ```bash
-# Following tested on OSX.
-bazel build //:Duke
-./bazel-bin/Duke
+# bazel makes a wrapper script around the jar file.
+bazel build //:Duke && ./bazel-bin/Duke
+
+# or simply
+bazel run //:Duke
 ```
 
-## Testing
+To build jar file for deployment purposes:
+```bash
+bazel build //:Duke_deploy.jar
+
+java -jar ./bazel-bin/Duke_deploy.jar
+```
 
+## Testing
+For unit tests:
 ```bash
 bazel test --test_output=all //...
 ```
-
-## Setting up in Intellij
-
-Prerequisites: JDK 11, update Intellij to the most recent version.
-
-1. Open Intellij (if you are not in the welcome screen, click `File` > `Close Project` to close the existing project first)
-1. Open the project into Intellij as follows:
-   1. Click `Open`.
-   1. Select the project directory, and click `OK`.
-   1. If there are any further prompts, accept the defaults.
-1. Configure the project to use **JDK 11** (not other versions) as explained in [here](https://www.jetbrains.com/help/idea/sdk.html#set-up-jdk).<br>
-   In the same dialog, set the **Project language level** field to the `SDK default` option.
-3. After that, locate the `src/main/java/Duke.java` file, right-click it, and choose `Run Duke.main()` (if the code editor is showing compile errors, try restarting the IDE). If the setup is correct, you should see something like the below as the output:
-   ```
-   Hello from
-    ____        _        
-   |  _ \ _   _| | _____ 
-   | | | | | | | |/ / _ \
-   | |_| | |_| |   <  __/
-   |____/ \__,_|_|\_\___|
-   ```
+For terminal ui tests (`text-ui-test`):
+```bash
+cd text-ui-test
+./runtest.sh
+```

From f30fd0645b6087b995fb7e4c176a17180a6ea2ad Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Tue, 24 Aug 2021 20:15:36 +0800
Subject: [PATCH 14/32] Run through google-java-format. Add checkstyle config.
 (#1)

---
 README.md                                     |   6 +
 config/checkstyle/checkstyle.xml              | 403 ++++++++++++++++++
 config/checkstyle/suppressions.xml            |  10 +
 .../java/com/lockarhythm/cmdline/Duke.java    |  92 ++--
 .../responders/addlist/AddListResponder.java  |  28 +-
 .../responders/echo/EchoResponder.java        |   8 +-
 .../responders/exit/ExitResponder.java        |  12 +-
 .../markasdone/MarkAsDoneResponder.java       |  45 +-
 src/main/java/com/lockarhythm/tasks/Task.java |  58 ++-
 .../java/com/lockarhythm/tasks/TaskList.java  |  52 +--
 .../com/lockarhythm/cmdline/TestDuke.java     |  59 ++-
 .../addlist/TestAddListResponder.java         |  24 +-
 .../responders/echo/TestEchoResponder.java    |  17 +-
 .../responders/exit/TestExitResponder.java    |  27 +-
 .../markasdone/TestMarkAsDoneResponder.java   |  63 ++-
 .../java/com/lockarhythm/tasks/TestTask.java  |  12 +-
 .../com/lockarhythm/tasks/TestTaskList.java   |  18 +-
 17 files changed, 666 insertions(+), 268 deletions(-)
 create mode 100644 config/checkstyle/checkstyle.xml
 create mode 100644 config/checkstyle/suppressions.xml

diff --git a/README.md b/README.md
index 31020453..5bf303dd 100644
--- a/README.md
+++ b/README.md
@@ -31,3 +31,9 @@ For terminal ui tests (`text-ui-test`):
 cd text-ui-test
 ./runtest.sh
 ```
+
+## Code Formatting & Style
+Use [google-java-format](https://github.com/google/google-java-format):
+```bash
+google-java-format --replace **/*.java # executes recursively
+```
diff --git a/config/checkstyle/checkstyle.xml b/config/checkstyle/checkstyle.xml
new file mode 100644
index 00000000..4c001417
--- /dev/null
+++ b/config/checkstyle/checkstyle.xml
@@ -0,0 +1,403 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE module PUBLIC
+    "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
+    "https://checkstyle.org/dtds/configuration_1_3.dtd">
+
+<!--
+    This configuration file enforces rules for a modified version of the module's code standard at
+    https://oss-generic.github.io/process/codingstandards/coding-standards-java.html
+-->
+
+<module name="Checker">
+
+  <module name="FileTabCharacter">
+    <!-- Checks that there are no tab characters in the file. -->
+  </module>
+
+  <module name="NewlineAtEndOfFile">
+    <!-- Accept LF, CR or CRLF to accomodate devs who prefer different line endings -->
+    <property name="lineSeparator" value="lf_cr_crlf"/>
+  </module>
+
+  <module name="RegexpSingleline">
+    <!-- Checks that FIXME is not used in comments.  TODO is preferred. -->
+    <property name="format" value="((//.*)|(\*.*))FIXME" />
+    <property name="message" value='TODO is preferred to FIXME."' />
+  </module>
+
+  <module name="SuppressionFilter">
+    <property name="file" value="${config_loc}/suppressions.xml"/>
+  </module>
+
+  <module name="LineLength">
+    <!-- Checks if a line is too long. -->
+    <property name="max" value="120"/>
+  </module>
+
+  <!-- All Java AST specific tests live under TreeWalker module. -->
+  <module name="TreeWalker">
+
+    <!-- Required to allow exceptions in code style -->
+    <module name="SuppressionCommentFilter">
+      <property name="offCommentFormat" value="CHECKSTYLE.OFF\: ([\w\|]+)"/>
+      <property name="onCommentFormat" value="CHECKSTYLE.ON\: ([\w\|]+)"/>
+      <property name="checkFormat" value="$1"/>
+    </module>
+
+    <!--
+    IMPORT CHECKS
+    -->
+
+    <!-- Checks the ordering of import statements follow the rules that the default Eclipse formatter uses.
+    The order rule "STATIC###STANDARD_JAVA_PACKAGE###SPECIAL_IMPORTS###THIRD_PARTY_PACKAGE" consists of:
+      1. STATIC: static imports
+      2. STANDARD_JAVA_PACKAGE: standard java/javax imports
+      3. SPECIAL_IMPORTS: defined as org imports
+      4. THIRD_PARTY_PACKAGE: defined as com imports
+    -->
+    <module name="CustomImportOrder">
+        <property name="customImportOrderRules"
+            value="STATIC###STANDARD_JAVA_PACKAGE###SPECIAL_IMPORTS###THIRD_PARTY_PACKAGE"/>
+        <property name="specialImportsRegExp" value="^org\."/>
+        <property name="thirdPartyPackageRegExp" value="^com\."/>
+        <property name="sortImportsInGroupAlphabetically" value="true"/>
+    </module>
+
+    <!-- Checks for redundant import statements.
+    An import statement is redundant if:
+      * It is a duplicate of another import. This is, when a class is imported more than once.
+      * The class non-statically imported is from the java.lang package, e.g. importing java.lang.String.
+      * The class non-statically imported is from the same package as the current package.
+    -->
+    <module name="RedundantImport"/>
+
+    <!-- Checks for unused import statements.
+    An import statement is unused if:
+      It's not referenced in the file.
+    -->
+    <module name="UnusedImports"/>
+
+    <module name="AvoidStarImport"/>
+
+    <!--
+    NAMING CHECKS
+    -->
+
+    <!-- Validate abbreviations (consecutive capital letters) length in identifier name -->
+    <module name="AbbreviationAsWordInName">
+      <property name="ignoreFinal" value="false"/>
+      <property name="allowedAbbreviationLength" value="1"/>
+    </module>
+
+    <module name="PackageName">
+      <!-- Validates identifiers for package names against the supplied expression. -->
+      <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]{1,})*$"/>
+      <property name="severity" value="warning"/>
+    </module>
+
+    <module name="TypeName">
+      <!-- Validates static, final fields against the expression "^[A-Z][a-zA-Z0-9]*$". -->
+      <metadata name="altname" value="TypeName"/>
+      <property name="severity" value="warning"/>
+    </module>
+
+    <module name="ConstantName">
+      <!-- Validates non-private, static, final fields against the expression "^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$". -->
+      <metadata name="altname" value="ConstantName"/>
+      <property name="applyToPrivate" value="false"/>
+      <message key="name.invalidPattern"
+               value="Variable ''{0}'' should be in ALL_CAPS (if it is a constant) or be private (otherwise)."/>
+      <property name="severity" value="warning"/>
+    </module>
+
+    <module name="StaticVariableName">
+      <!-- Validates static, non-final fields against the supplied expression. -->
+      <metadata name="altname" value="StaticVariableName"/>
+      <property name="format" value="^[a-z][a-zA-Z0-9]*_?$"/>
+      <property name="severity" value="warning"/>
+    </module>
+
+    <module name="MemberName">
+      <!-- Validates non-static members against the supplied expression. -->
+      <metadata name="altname" value="MemberName"/>
+      <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
+      <property name="severity" value="warning"/>
+    </module>
+
+    <module name="MethodName">
+      <!-- Validates identifiers for method names against the supplied expression. -->
+      <metadata name="altname" value="MethodName"/>
+      <property name="format" value="^[a-z][a-zA-Z0-9]*(_[a-z][a-zA-Z0-9]+){0,2}$"/>
+    </module>
+
+    <module name="ParameterName">
+      <!-- Validates identifiers for method parameters against the expression "^[a-z][a-zA-Z0-9]*$". -->
+      <property name="severity" value="warning"/>
+    </module>
+
+    <module name="LocalFinalVariableName">
+      <!-- Validates identifiers for local final variables against the expression "^[a-z][a-zA-Z0-9]*$". -->
+      <property name="severity" value="warning"/>
+    </module>
+
+    <module name="LocalVariableName">
+      <!-- Validates identifiers for local variables against the expression "^[a-z][a-zA-Z0-9]*$". -->
+      <property name="severity" value="warning"/>
+    </module>
+
+
+    <!--
+    LENGTH and CODING CHECKS
+    -->
+
+    <!-- Checks that array type declarations follow Java Style
+      Java style: public static void main(String[] args) // Allowed
+      C style:    public static void main(String args[]) // Not allowed
+    -->
+    <module name="ArrayTypeStyle"/>
+
+    <!-- Checks if a catch block is empty and does not contain any comments. -->
+    <module name="EmptyCatchBlock"/>
+
+    <module name="LeftCurly">
+      <!-- Checks for placement of the left curly brace ('{'). -->
+      <property name="severity" value="warning"/>
+    </module>
+
+    <module name="RightCurly">
+      <!-- Checks right curlies on CATCH, ELSE, and TRY blocks are on
+      the same line. e.g., the following example is fine:
+      <pre>
+        if {
+          ...
+        } else
+      </pre>
+      -->
+      <!-- This next example is not fine:
+      <pre>
+        if {
+          ...
+        }
+        else
+      </pre>
+      -->
+      <property name="severity" value="warning"/>
+    </module>
+
+    <!-- Checks for braces around loop blocks -->
+    <module name="NeedBraces">
+      <!--
+      if (true) return 1; // Not allowed
+
+      if (true) { return 1; } // Not allowed
+
+      else if {
+        return 1; // else if should always be multi line
+      }
+
+      if (true)
+        return 1; // Not allowed
+      -->
+      <property name="allowEmptyLoopBody" value="true"/>
+    </module>
+
+    <!-- Checks that each variable declaration is in its own statement and on its own line. -->
+    <module name="MultipleVariableDeclarations"/>
+
+    <module name="OneStatementPerLine"/>
+
+    <!-- Checks that long constants are defined with an upper ell.-->
+    <module name="UpperEll" />
+
+    <module name="FallThrough">
+      <!-- Warn about falling through to the next case statement.  Similar to
+      javac -Xlint:fallthrough, but the check is suppressed if a single-line comment
+      on the last non-blank line preceding the fallen-into case contains 'fall through' (or
+      some other variants which we don't publicized to promote consistency).
+      -->
+      <property name="reliefPattern"
+       value="fall through|Fall through|fallthru|Fallthru|falls through|Falls through|fallthrough|Fallthrough|No break|NO break|no break|continue on"/>
+    </module>
+
+    <module name="MissingSwitchDefault"/>
+
+    <!-- Checks that Class variables should never be declared public. -->
+    <module name="VisibilityModifier">
+      <property name="protectedAllowed" value="true"/>
+      <property name="allowPublicFinalFields" value="true"/>
+      <property name="ignoreAnnotationCanonicalNames" value="RegisterExtension, TempDir"/>
+    </module>
+
+    <!--
+    ORDER CHECKS
+    -->
+
+    <!-- Checks that the order of at-clauses follows the tagOrder default property value order.
+         @author, @version, @param, @return, @throws, @exception, @see, @since, @serial, @serialField, @serialData, @deprecated
+    -->
+    <module name="AtclauseOrder"/>
+
+    <!-- Checks if the Class and Interface declarations is organized in this order
+      1. Class (static) variables. Order: public, protected, package level (no access modifier), private.
+      2. Instance variables. Order: public, protected, package level (no access modifier), private.
+      3. Constructors
+      4. Methods
+    -->
+    <module name ="DeclarationOrder"/>
+
+    <module name="ModifierOrder">
+      <!-- Warn if modifier order is inconsistent with JLS3 8.1.1, 8.3.1, and
+           8.4.3.  The prescribed order is:
+           public, protected, private, abstract, static, final, transient, volatile,
+           synchronized, native, strictfp
+        -->
+    </module>
+
+    <module name="OverloadMethodsDeclarationOrder"/>
+
+    <!--
+    WHITESPACE CHECKS
+    -->
+
+    <!-- Checks that comments are indented relative to their position in the code -->
+    <module name="CommentsIndentation"/>
+
+    <module name="WhitespaceAround">
+      <!-- Checks that various tokens are surrounded by whitespace.
+           This includes most binary operators and keywords followed
+           by regular or curly braces.
+      -->
+      <property name="tokens" value="ASSIGN, BAND, BAND_ASSIGN, BOR,
+        BOR_ASSIGN, BSR, BSR_ASSIGN, BXOR, BXOR_ASSIGN, COLON, DIV, DIV_ASSIGN,
+        EQUAL, GE, GT, LAND, LCURLY, LE, LITERAL_CATCH, LITERAL_DO, LITERAL_ELSE,
+        LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF, LITERAL_RETURN,
+        LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE, LOR, LT, MINUS,
+        MINUS_ASSIGN, MOD, MOD_ASSIGN, NOT_EQUAL, PLUS, PLUS_ASSIGN, QUESTION,
+        RCURLY, SL, SLIST, SL_ASSIGN, SR_ASSIGN, STAR, STAR_ASSIGN"/>
+      <!-- Allow empty constructors e.g. MyClass() {} -->
+      <property name="allowEmptyConstructors" value="true" />
+      <!-- Allow empty methods e.g. void func() {} -->
+      <property name="allowEmptyMethods" value="true" />
+      <!-- Allow empty types e.g. class Foo {}, enum Foo {} -->
+      <property name="allowEmptyTypes" value="true" />
+      <!-- Allow empty loops e.g. for (int i = 1; i > 1; i++) {} -->
+      <property name="allowEmptyLoops" value="true" />
+      <!-- Allow empty lambdas e.g. () -> {} -->
+      <property name="allowEmptyLambdas" value="true" />
+    </module>
+
+    <module name="WhitespaceAfter">
+      <!-- Checks that commas, semicolons and typecasts are followed by whitespace. -->
+      <property name="tokens" value="COMMA, SEMI, TYPECAST"/>
+    </module>
+
+    <module name="NoWhitespaceAfter">
+      <!-- Checks that there is no whitespace after various unary operators. Linebreaks are allowed. -->
+      <property name="tokens" value="BNOT, DEC, DOT, INC, LNOT, UNARY_MINUS,
+        UNARY_PLUS"/>
+      <property name="allowLineBreaks" value="true"/>
+    </module>
+
+    <!-- No trailing whitespace -->
+    <module name="Regexp">
+      <property name="format" value="[ \t]+$"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Trailing whitespace"/>
+    </module>
+
+    <module name="OperatorWrap">
+      <!-- Checks that the non-assignment type operator is at the next line in a line wrap.
+           This includes "?", ":", "==", "!=", "/", "+", "-", "*", "%", ">>", ">>>",
+           ">=", ">", "<<", "<=", "<", "^", "|", "||", "&", "&&", "instanceof",
+           "&" when used in a generic upper or lower bounds constraints,
+             e.g. <T extends Foo & Bar>
+           "::" when used as a reference to a method or constructor without arguments.
+             e.g. String::compareToIgnoreCase
+      -->
+      <property name="tokens" value="QUESTION, COLON, EQUAL, NOT_EQUAL, DIV, PLUS, MINUS, STAR, MOD, SR, BSR,
+        GE, GT, SL, LE, LT, BXOR, BOR, LOR, BAND, LAND, LITERAL_INSTANCEOF, TYPE_EXTENSION_AND, METHOD_REF"/>
+      <property name="option" value="nl"/>
+    </module>
+    <module name="OperatorWrap">
+      <!-- Checks that the assignment type operator is at the previous end of line in a line wrap.
+           This includes "=", "/=", "+=", "-=", "*=", "%=", ">>=", ">>>=", "<<=", "^=", "&=".
+      -->
+      <property name="tokens" value="ASSIGN, DIV_ASSIGN, PLUS_ASSIGN, MINUS_ASSIGN, STAR_ASSIGN, MOD_ASSIGN,
+        SR_ASSIGN, BSR_ASSIGN, SL_ASSIGN, BXOR_ASSIGN, BOR_ASSIGN, BAND_ASSIGN"/>
+      <property name="option" value="eol"/>
+    </module>
+
+    <module name="SeparatorWrap">
+      <!-- Checks that the ".", "@" is at the next line in a line wrap. -->
+      <property name="tokens" value="DOT, AT"/>
+      <property name="option" value="nl"/>
+    </module>
+    <module name="SeparatorWrap">
+      <!-- Checks that the ",", "]", "[", "...", ";", "(" is at the previous end of line in a line wrap. -->
+      <property name="tokens" value="COMMA, RBRACK, ARRAY_DECLARATOR, ELLIPSIS, SEMI, LPAREN"/>
+      <property name="option" value="eol"/>
+    </module>
+
+    <module name="Indentation">
+      <property name="caseIndent" value="0" />
+    </module>
+
+    <module name="NoWhitespaceBefore">
+      <!-- Checks that there is no whitespace before various unary operators. Linebreaks are allowed. -->
+      <property name="tokens" value="SEMI, DOT, POST_DEC, POST_INC"/>
+      <property name="allowLineBreaks" value="true"/>
+    </module>
+
+    <module name="ParenPad">
+      <!-- Checks that there is no whitespace before close parenthesis or after open parenthesis. -->
+      <property name="severity" value="warning"/>
+    </module>
+
+    <!-- Checks that non-whitespace characters are separated by no more than one whitespace character.
+         a = 1; // Allowed
+         a  = 1; // Not allowed (more than one space before =)
+    -->
+    <module name="SingleSpaceSeparator">
+      <!-- Validate whitespace surrounding comments as well.
+
+           a = 1; // Allowed (single space before start of comment)
+           a = 1; /* Allowed (single space before start of comment) */
+           /* Allowed (single space after end of comment) */ a = 1;
+           a = 1;  // Not allowed (more than one space before start of comment)
+           a = 1;  /* Not allowed (more than one space before start of comment) */
+           /* Not allowed (more than one space after end of comment) */  a = 1;
+
+           This doesn't validate whitespace within comments so a comment /* like  this */ is allowed.
+      -->
+      <property name="validateComments" value="true"/>
+    </module>
+
+    <!--
+    JAVADOC CHECKS
+    -->
+
+    <!-- Checks that every class, enumeration and interface have a header comment. -->
+    <module name="JavadocType">
+      <property name="allowMissingParamTags" value="true"/>
+    </module>
+
+    <!-- Checks that every public method (excluding getters, setters and constructors) has a header comment. -->
+    <module name="JavadocMethod">
+      <property name="allowedAnnotations" value="Override, Test, BeforeAll, BeforeEach, AfterAll, AfterEach, Subscribe"/>
+      <property name="scope" value="public"/>
+      <property name="validateThrows" value="false"/>
+      <property name="allowMissingParamTags" value="true"/>
+      <property name="allowMissingReturnTag" value="true"/>
+      <property name="tokens" value="METHOD_DEF, ANNOTATION_FIELD_DEF"/>
+    </module>
+
+    <module name="InvalidJavadocPosition"/>
+
+    <module name="MissingJavadocMethodCheck">
+      <property name="minLineCount" value="1"/>
+      <property name="allowMissingPropertyJavadoc" value="true"/>
+      <property name="ignoreMethodNamesRegex" value="(set.*|get.*)"/>
+    </module>
+
+  </module>
+</module>
diff --git a/config/checkstyle/suppressions.xml b/config/checkstyle/suppressions.xml
new file mode 100644
index 00000000..39efb6e4
--- /dev/null
+++ b/config/checkstyle/suppressions.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0"?>
+
+<!DOCTYPE suppressions PUBLIC
+    "-//Checkstyle//DTD SuppressionFilter Configuration 1.2//EN"
+    "https://checkstyle.org/dtds/suppressions_1_2.dtd">
+
+<suppressions>
+  <suppress checks="JavadocType" files=".*Test\.java"/>
+  <suppress checks="MissingJavadocMethodCheck" files=".*Test\.java"/>
+</suppressions>
diff --git a/src/main/java/com/lockarhythm/cmdline/Duke.java b/src/main/java/com/lockarhythm/cmdline/Duke.java
index 63a50e3e..8697a580 100644
--- a/src/main/java/com/lockarhythm/cmdline/Duke.java
+++ b/src/main/java/com/lockarhythm/cmdline/Duke.java
@@ -1,64 +1,62 @@
 package com.lockarhythm.cmdline;
 
-import java.util.Scanner;
-import java.util.Arrays;
-
 import com.lockarhythm.responders.QueryRespondable;
 import com.lockarhythm.responders.Response;
-import com.lockarhythm.responders.exit.ExitResponder;
 import com.lockarhythm.responders.addlist.AddListResponder;
+import com.lockarhythm.responders.exit.ExitResponder;
 import com.lockarhythm.responders.markasdone.MarkAsDoneResponder;
 import com.lockarhythm.tasks.TaskList;
+import java.util.Arrays;
+import java.util.Scanner;
 
 public class Duke {
-    static String logo =   " \t____        _        \n"
-                           + "\t|  _ \\ _   _| | _____ \n"
-                           + "\t| | | | | | | |/ / _ \\\n"
-                           + "\t| |_| | |_| |   <  __/\n"
-                           + "\t|____/ \\__,_|_|\\_\\___|\n";
-
-    static TaskList list = new TaskList();
-
-    static QueryRespondable[] responders = {
-        new ExitResponder(),
-        new MarkAsDoneResponder(list),
-        new AddListResponder(list),
-    };
-
-    private static void print(String ...strings) {
-        System.out.println("\t____________________________________________________________");
-        for (String s : strings) {
-            s = Arrays.stream(s.split("\n")).map(x -> "\t" + x).reduce("", (x, y) -> x + y + "\n");
-            System.out.println(s);
-        }
-        System.out.println("\t____________________________________________________________\n");
+  static String logo =
+      " \t____        _        \n"
+          + "\t|  _ \\ _   _| | _____ \n"
+          + "\t| | | | | | | |/ / _ \\\n"
+          + "\t| |_| | |_| |   <  __/\n"
+          + "\t|____/ \\__,_|_|\\_\\___|\n";
+
+  static TaskList list = new TaskList();
+
+  static QueryRespondable[] responders = {
+    new ExitResponder(), new MarkAsDoneResponder(list), new AddListResponder(list),
+  };
+
+  private static void print(String... strings) {
+    System.out.println("\t____________________________________________________________");
+    for (String s : strings) {
+      s = Arrays.stream(s.split("\n")).map(x -> "\t" + x).reduce("", (x, y) -> x + y + "\n");
+      System.out.println(s);
     }
-
-    private static Response getResponse(String query) {
-        Response res = null;
-        for (QueryRespondable responder : responders) {
-            res = responder.respondTo(query);
-            if (res != null) {
-                return res;
-            }
-        }
+    System.out.println("\t____________________________________________________________\n");
+  }
+
+  private static Response getResponse(String query) {
+    Response res = null;
+    for (QueryRespondable responder : responders) {
+      res = responder.respondTo(query);
+      if (res != null) {
         return res;
+      }
     }
+    return res;
+  }
 
-    public static void main(String[] args) {
-        String line;
-        Scanner in = new Scanner(System.in);
-
-        print("Hello I'm\n" + logo, "What can I do for you?");
+  public static void main(String[] args) {
+    String line;
+    Scanner in = new Scanner(System.in);
 
-        line = in.nextLine();
-        Response res = getResponse(line);
-        while(!res.shouldExit()) {
-            print(res.getText());
-            line = in.nextLine();
-            res = getResponse(line);
-        }
+    print("Hello I'm\n" + logo, "What can I do for you?");
 
-        print(res.getText());
+    line = in.nextLine();
+    Response res = getResponse(line);
+    while (!res.shouldExit()) {
+      print(res.getText());
+      line = in.nextLine();
+      res = getResponse(line);
     }
+
+    print(res.getText());
+  }
 }
diff --git a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
index 7205d87f..6253ca51 100644
--- a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
+++ b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
@@ -1,26 +1,22 @@
 package com.lockarhythm.responders.addlist;
 
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-
-import com.lockarhythm.responders.Response;
 import com.lockarhythm.responders.QueryRespondable;
-
+import com.lockarhythm.responders.Response;
 import com.lockarhythm.tasks.TaskList;
 
 public class AddListResponder implements QueryRespondable {
-    private TaskList list;
+  private TaskList list;
 
-    public AddListResponder(TaskList list) {
-        this.list = list;
-    }
+  public AddListResponder(TaskList list) {
+    this.list = list;
+  }
 
-    public Response respondTo(String query) {
-        if (query.equals("list")) {
-            return new Response("Here are the tasks in your list:\n"+list.toString(), false);
-        }
-        // by default, adds the given query.
-        list.add(query);
-        return new Response("added: " + query, false);
+  public Response respondTo(String query) {
+    if (query.equals("list")) {
+      return new Response("Here are the tasks in your list:\n" + list.toString(), false);
     }
+    // by default, adds the given query.
+    list.add(query);
+    return new Response("added: " + query, false);
+  }
 }
diff --git a/src/main/java/com/lockarhythm/responders/echo/EchoResponder.java b/src/main/java/com/lockarhythm/responders/echo/EchoResponder.java
index 7547ba76..214acc5f 100644
--- a/src/main/java/com/lockarhythm/responders/echo/EchoResponder.java
+++ b/src/main/java/com/lockarhythm/responders/echo/EchoResponder.java
@@ -1,10 +1,10 @@
 package com.lockarhythm.responders.echo;
 
-import com.lockarhythm.responders.Response;
 import com.lockarhythm.responders.QueryRespondable;
+import com.lockarhythm.responders.Response;
 
 public class EchoResponder implements QueryRespondable {
-    public Response respondTo(String query) {
-        return new Response(query, false);
-    }
+  public Response respondTo(String query) {
+    return new Response(query, false);
+  }
 }
diff --git a/src/main/java/com/lockarhythm/responders/exit/ExitResponder.java b/src/main/java/com/lockarhythm/responders/exit/ExitResponder.java
index 34a1bb32..0206732b 100644
--- a/src/main/java/com/lockarhythm/responders/exit/ExitResponder.java
+++ b/src/main/java/com/lockarhythm/responders/exit/ExitResponder.java
@@ -1,13 +1,13 @@
 package com.lockarhythm.responders.exit;
 
-import com.lockarhythm.responders.Response;
 import com.lockarhythm.responders.QueryRespondable;
+import com.lockarhythm.responders.Response;
 
 public class ExitResponder implements QueryRespondable {
-    public Response respondTo(String query) {
-        if (query.equals("bye")) {
-            return new Response("Bye. Hope to see you again soon!", true);
-        }
-        return null;
+  public Response respondTo(String query) {
+    if (query.equals("bye")) {
+      return new Response("Bye. Hope to see you again soon!", true);
     }
+    return null;
+  }
 }
diff --git a/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java b/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
index c7d66246..182c4230 100644
--- a/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
+++ b/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
@@ -1,33 +1,32 @@
 package com.lockarhythm.responders.markasdone;
 
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-
-import com.lockarhythm.responders.Response;
 import com.lockarhythm.responders.QueryRespondable;
-
-import com.lockarhythm.tasks.TaskList;
+import com.lockarhythm.responders.Response;
 import com.lockarhythm.tasks.Task;
+import com.lockarhythm.tasks.TaskList;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 public class MarkAsDoneResponder implements QueryRespondable {
-    private static String doneCommandPrefix = "done ";
-    private TaskList list;
-    Pattern pattern = Pattern.compile(doneCommandPrefix+"(\\d+)");
+  private static String doneCommandPrefix = "done ";
+  private TaskList list;
+  Pattern pattern = Pattern.compile(doneCommandPrefix + "(\\d+)");
 
-    public MarkAsDoneResponder(TaskList list) {
-        this.list = list;
-    }
+  public MarkAsDoneResponder(TaskList list) {
+    this.list = list;
+  }
 
-    public Response respondTo(String query) {
-        Matcher matcher = pattern.matcher(query);
-        if (matcher.find()) {
-            int i = Integer.parseInt(matcher.group(1));
-            if (i > 0 && i <= list.size()) {
-                Task task = list.markAsDone(i - 1);
-                return new Response("Nice! I've marked this task as done:\n\t" + task.toString(), false);
-            }
-            return new Response(String.format("Item %d is not on the list. I cannot mark it as done!", i), false);
-        }
-        return null;
+  public Response respondTo(String query) {
+    Matcher matcher = pattern.matcher(query);
+    if (matcher.find()) {
+      int i = Integer.parseInt(matcher.group(1));
+      if (i > 0 && i <= list.size()) {
+        Task task = list.markAsDone(i - 1);
+        return new Response("Nice! I've marked this task as done:\n\t" + task.toString(), false);
+      }
+      return new Response(
+          String.format("Item %d is not on the list. I cannot mark it as done!", i), false);
     }
+    return null;
+  }
 }
diff --git a/src/main/java/com/lockarhythm/tasks/Task.java b/src/main/java/com/lockarhythm/tasks/Task.java
index 1230cbdd..943f6749 100644
--- a/src/main/java/com/lockarhythm/tasks/Task.java
+++ b/src/main/java/com/lockarhythm/tasks/Task.java
@@ -1,34 +1,32 @@
 package com.lockarhythm.tasks;
 
-import java.util.ArrayList;
-
 public class Task {
-    private String description;
-    private boolean isDone;
-
-    public Task(String description) {
-        this.description = description;
-        this.isDone = false;
-    }
-
-    public void toggleDone() {
-        this.isDone = !this.isDone;
-    }
-
-    public String getDescription() {
-      return description;
-    }
-
-    public boolean isDone() {
-      return isDone;
-    }
-
-    private String getDoneIcon() {
-      return isDone ? "X" : " ";
-    }
-
-    @Override
-    public String toString() {
-        return String.format("[%s] %s", getDoneIcon(), description);
-    }
+  private String description;
+  private boolean isDone;
+
+  public Task(String description) {
+    this.description = description;
+    this.isDone = false;
+  }
+
+  public void toggleDone() {
+    this.isDone = !this.isDone;
+  }
+
+  public String getDescription() {
+    return description;
+  }
+
+  public boolean isDone() {
+    return isDone;
+  }
+
+  private String getDoneIcon() {
+    return isDone ? "X" : " ";
+  }
+
+  @Override
+  public String toString() {
+    return String.format("[%s] %s", getDoneIcon(), description);
+  }
 }
diff --git a/src/main/java/com/lockarhythm/tasks/TaskList.java b/src/main/java/com/lockarhythm/tasks/TaskList.java
index 2f514aa0..9732d032 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskList.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskList.java
@@ -3,36 +3,36 @@
 import java.util.ArrayList;
 
 public class TaskList {
-    private ArrayList<Task> list;
+  private ArrayList<Task> list;
 
-    public TaskList() {
-        list = new ArrayList<Task>();
-    }
+  public TaskList() {
+    list = new ArrayList<Task>();
+  }
 
-    public int size() {
-        return list.size();
-    }
+  public int size() {
+    return list.size();
+  }
 
-    public void add(String description) {
-        list.add(new Task(description));
-    }
+  public void add(String description) {
+    list.add(new Task(description));
+  }
 
-    public Task markAsDone(int index) {
-        Task t = list.get(index);
-        t.toggleDone();
-        return t;
-    }
+  public Task markAsDone(int index) {
+    Task t = list.get(index);
+    t.toggleDone();
+    return t;
+  }
 
-    @Override
-    public String toString() {
-        StringBuilder s = new StringBuilder();
-        int i = 1;
-        for (i = 0; i < list.size(); i++) {
-            s.append(i+1);
-            s.append(".");
-            s.append(list.get(i));
-            s.append("\n");
-        }
-        return s.toString();
+  @Override
+  public String toString() {
+    StringBuilder s = new StringBuilder();
+    int i = 1;
+    for (i = 0; i < list.size(); i++) {
+      s.append(i + 1);
+      s.append(".");
+      s.append(list.get(i));
+      s.append("\n");
     }
+    return s.toString();
+  }
 }
diff --git a/src/test/java/com/lockarhythm/cmdline/TestDuke.java b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
index 9a291299..a2d69327 100644
--- a/src/test/java/com/lockarhythm/cmdline/TestDuke.java
+++ b/src/test/java/com/lockarhythm/cmdline/TestDuke.java
@@ -2,40 +2,35 @@
 
 import static org.junit.Assert.*;
 
-import org.junit.Test;
-
-import java.io.ByteArrayOutputStream;
 import java.io.ByteArrayInputStream;
-import java.io.PrintStream;
+import java.io.ByteArrayOutputStream;
 import java.io.InputStream;
-import java.nio.file.Files;
-import java.nio.file.Paths;
+import java.io.PrintStream;
+import org.junit.Test;
 
 public class TestDuke {
-    private final PrintStream standardOut = System.out;
-    private final InputStream standardIn = System.in;
-    private final ByteArrayOutputStream out = new ByteArrayOutputStream();
-    private final ByteArrayInputStream in = new ByteArrayInputStream(
-        "read book\nreturn book\nlist\nbye".getBytes()
-    );
-
-    @Test
-    public void testMeetsLevel2() throws Exception {
-        System.setIn(in);
-        System.setOut(new PrintStream(out));
-
-        Duke.main(null);
-        String output = out.toString().trim();
-        assertFalse(output.isEmpty());
-
-        assertTrue("it adds the 1st item", output.contains("added: read book"));
-        assertTrue("it adds the 2nd item", output.contains("added: return book"));
-        assertTrue("it lists the items", output.contains("1.[ ] read book"));
-        assertTrue("it lists the items", output.contains("2.[ ] return book"));
-        assertTrue("it exits", output.contains("Bye. Hope to see you again soon!"));
-
-        System.setOut(standardOut);
-        System.setIn(standardIn);
-    }
-
+  private final PrintStream standardOut = System.out;
+  private final InputStream standardIn = System.in;
+  private final ByteArrayOutputStream out = new ByteArrayOutputStream();
+  private final ByteArrayInputStream in =
+      new ByteArrayInputStream("read book\nreturn book\nlist\nbye".getBytes());
+
+  @Test
+  public void testMeetsLevel2() throws Exception {
+    System.setIn(in);
+    System.setOut(new PrintStream(out));
+
+    Duke.main(null);
+    String output = out.toString().trim();
+    assertFalse(output.isEmpty());
+
+    assertTrue("it adds the 1st item", output.contains("added: read book"));
+    assertTrue("it adds the 2nd item", output.contains("added: return book"));
+    assertTrue("it lists the items", output.contains("1.[ ] read book"));
+    assertTrue("it lists the items", output.contains("2.[ ] return book"));
+    assertTrue("it exits", output.contains("Bye. Hope to see you again soon!"));
+
+    System.setOut(standardOut);
+    System.setIn(standardIn);
+  }
 }
diff --git a/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java b/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
index 306f6f64..8e2d0cdb 100644
--- a/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
+++ b/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
@@ -2,24 +2,22 @@
 
 import static org.junit.Assert.*;
 
-import org.junit.Test;
-
 import com.lockarhythm.responders.Response;
 import com.lockarhythm.tasks.TaskList;
+import org.junit.Test;
 
 public class TestAddListResponder {
-    @Test
-    public void testAddsItemsAndLists() throws Exception {
-        AddListResponder responder = new AddListResponder(new TaskList());
-
-        Response res = responder.respondTo("read book");
-        assertEquals("added: read book", res.getText());
+  @Test
+  public void testAddsItemsAndLists() throws Exception {
+    AddListResponder responder = new AddListResponder(new TaskList());
 
-        res = responder.respondTo("return book");
-        assertEquals("added: return book", res.getText());
+    Response res = responder.respondTo("read book");
+    assertEquals("added: read book", res.getText());
 
-        res = responder.respondTo("list");
-        assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
+    res = responder.respondTo("return book");
+    assertEquals("added: return book", res.getText());
 
-    }
+    res = responder.respondTo("list");
+    assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
+  }
 }
diff --git a/src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java b/src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java
index e883f6f8..e51c34a6 100644
--- a/src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java
+++ b/src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java
@@ -2,17 +2,16 @@
 
 import static org.junit.Assert.*;
 
-import org.junit.Test;
-
 import com.lockarhythm.responders.Response;
+import org.junit.Test;
 
 public class TestEchoResponder {
-    @Test
-    public void testEchosBackText() throws Exception {
-        EchoResponder responder = new EchoResponder();
-        Response res = responder.respondTo("hello");
+  @Test
+  public void testEchosBackText() throws Exception {
+    EchoResponder responder = new EchoResponder();
+    Response res = responder.respondTo("hello");
 
-        assertEquals("hello", res.getText());
-        assertFalse(res.shouldExit());
-    }
+    assertEquals("hello", res.getText());
+    assertFalse(res.shouldExit());
+  }
 }
diff --git a/src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java b/src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java
index f2007459..b3f18bd3 100644
--- a/src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java
+++ b/src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java
@@ -2,24 +2,23 @@
 
 import static org.junit.Assert.*;
 
-import org.junit.Test;
-
 import com.lockarhythm.responders.Response;
+import org.junit.Test;
 
 public class TestExitResponder {
-    @Test
-    public void testExitsOnKeyword() throws Exception {
-        ExitResponder responder = new ExitResponder();
-        Response res = responder.respondTo("bye");
+  @Test
+  public void testExitsOnKeyword() throws Exception {
+    ExitResponder responder = new ExitResponder();
+    Response res = responder.respondTo("bye");
 
-        assertTrue(res.shouldExit());
-    }
+    assertTrue(res.shouldExit());
+  }
 
-    @Test
-    public void testNullOnNonkeyword() throws Exception {
-        ExitResponder responder = new ExitResponder();
-        Response res = responder.respondTo("hello");
+  @Test
+  public void testNullOnNonkeyword() throws Exception {
+    ExitResponder responder = new ExitResponder();
+    Response res = responder.respondTo("hello");
 
-        assertNull(res);
-    }
+    assertNull(res);
+  }
 }
diff --git a/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java b/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java
index b4c51647..c87d6f4c 100644
--- a/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java
+++ b/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java
@@ -2,51 +2,48 @@
 
 import static org.junit.Assert.*;
 
-import org.junit.Test;
-
 import com.lockarhythm.responders.Response;
 import com.lockarhythm.responders.addlist.AddListResponder;
 import com.lockarhythm.tasks.TaskList;
+import org.junit.Test;
 
 public class TestMarkAsDoneResponder {
-    @Test
-    public void testMarkAsDoneHappyPath() throws Exception {
-        TaskList list = new TaskList();
-        MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
-        AddListResponder alresponder = new AddListResponder(list);
-
-        Response res = alresponder.respondTo("read book");
-        assertEquals("added: read book", res.getText());
-
-        res = alresponder.respondTo("return book");
-        assertEquals("added: return book", res.getText());
+  @Test
+  public void testMarkAsDoneHappyPath() throws Exception {
+    TaskList list = new TaskList();
+    MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
+    AddListResponder alresponder = new AddListResponder(list);
 
-        res = mdresponder.respondTo("done 1");
-        assertTrue(res.getText().contains("Nice! I've marked this task as done"));
-        assertTrue(res.getText().contains("read book"));
+    Response res = alresponder.respondTo("read book");
+    assertEquals("added: read book", res.getText());
 
-        res = alresponder.respondTo("list");
-        assertTrue(res.getText().contains("1.[X] read book\n2.[ ] return book\n"));
+    res = alresponder.respondTo("return book");
+    assertEquals("added: return book", res.getText());
 
-    }
+    res = mdresponder.respondTo("done 1");
+    assertTrue(res.getText().contains("Nice! I've marked this task as done"));
+    assertTrue(res.getText().contains("read book"));
 
-    @Test
-    public void testMarkAsDoneOnNonExistentItem() throws Exception {
-        TaskList list = new TaskList();
-        MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
-        AddListResponder alresponder = new AddListResponder(list);
+    res = alresponder.respondTo("list");
+    assertTrue(res.getText().contains("1.[X] read book\n2.[ ] return book\n"));
+  }
 
-        Response res = alresponder.respondTo("read book");
-        assertEquals("added: read book", res.getText());
+  @Test
+  public void testMarkAsDoneOnNonExistentItem() throws Exception {
+    TaskList list = new TaskList();
+    MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
+    AddListResponder alresponder = new AddListResponder(list);
 
-        res = alresponder.respondTo("return book");
-        assertEquals("added: return book", res.getText());
+    Response res = alresponder.respondTo("read book");
+    assertEquals("added: read book", res.getText());
 
-        res = mdresponder.respondTo("done 10000");
-        assertTrue(res.getText().contains("Item 10000 is not on the list. I cannot mark it as done!"));
+    res = alresponder.respondTo("return book");
+    assertEquals("added: return book", res.getText());
 
-        res = alresponder.respondTo("list");
-        assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
+    res = mdresponder.respondTo("done 10000");
+    assertTrue(res.getText().contains("Item 10000 is not on the list. I cannot mark it as done!"));
 
-    }
+    res = alresponder.respondTo("list");
+    assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
+  }
 }
diff --git a/src/test/java/com/lockarhythm/tasks/TestTask.java b/src/test/java/com/lockarhythm/tasks/TestTask.java
index 87a3ed5d..f70783c3 100644
--- a/src/test/java/com/lockarhythm/tasks/TestTask.java
+++ b/src/test/java/com/lockarhythm/tasks/TestTask.java
@@ -5,11 +5,11 @@
 import org.junit.Test;
 
 public class TestTask {
-    @Test
-    public void testToggleDone() throws Exception {
-        Task task = new Task("learn java well");
+  @Test
+  public void testToggleDone() throws Exception {
+    Task task = new Task("learn java well");
 
-        task.toggleDone();
-        assertTrue("task should be done", task.isDone());
-    }
+    task.toggleDone();
+    assertTrue("task should be done", task.isDone());
+  }
 }
diff --git a/src/test/java/com/lockarhythm/tasks/TestTaskList.java b/src/test/java/com/lockarhythm/tasks/TestTaskList.java
index 5baa9133..ce5d6025 100644
--- a/src/test/java/com/lockarhythm/tasks/TestTaskList.java
+++ b/src/test/java/com/lockarhythm/tasks/TestTaskList.java
@@ -5,15 +5,15 @@
 import org.junit.Test;
 
 public class TestTaskList {
-    @Test
-    public void testAddTask() throws Exception {
-        TaskList list = new TaskList();
+  @Test
+  public void testAddTask() throws Exception {
+    TaskList list = new TaskList();
 
-        list.add("learn useful libraries in java");
-        list.add("learn bazel");
-        assertEquals("has correct number of items", 2, list.size());
+    list.add("learn useful libraries in java");
+    list.add("learn bazel");
+    assertEquals("has correct number of items", 2, list.size());
 
-        Task task = list.markAsDone(1);
-        assertEquals("can mark tasks as done", "learn bazel", task.getDescription());
-    }
+    Task task = list.markAsDone(1);
+    assertEquals("can mark tasks as done", "learn bazel", task.getDescription());
+  }
 }

From 6c2adf84ab35c06064f31b3317a4f315a96f4e6a Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Tue, 24 Aug 2021 21:18:43 +0800
Subject: [PATCH 15/32] Update README layout

Credits: https://undraw.co/license
---
 README.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 5bf303dd..fbe06bcc 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,6 @@
-# Duke project template
+<img src="https://user-images.githubusercontent.com/88638946/130622078-e049680c-7895-4725-ace0-49869574887c.png" width="50%" align="right">
+
+# Duke
 
 This is a project template for a greenfield Java project. It's named after the Java mascot _Duke_. Given below are instructions on how to use it.
 

From dd6438f0c3a910efd9fcbbbbfe5a37078f1d0d97 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Tue, 24 Aug 2021 23:36:12 +0800
Subject: [PATCH 16/32] Add pre-commit hook. (#2)

Helps to enforce code style before committing
---
 .gitignore              |  3 +++
 .pre-commit-config.yaml |  7 +++++++
 .pre-commit-hooks.yaml  |  8 ++++++++
 README.md               | 10 ++++++++++
 tools/format-code.sh    | 13 +++++++++++++
 5 files changed, 41 insertions(+)
 create mode 100644 .pre-commit-config.yaml
 create mode 100644 .pre-commit-hooks.yaml
 create mode 100644 tools/format-code.sh

diff --git a/.gitignore b/.gitignore
index 8256048a..b957cd08 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,3 +19,6 @@ text-ui-test/EXPECTED-UNIX.TXT
 # Ignore all bazel-* symlinks. There is no full list since this can change
 # based on the name of the directory bazel is cloned into.
 /bazel-*
+
+# for pre-commit git-hooks
+/.cache/*
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 00000000..f4b6f43b
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,7 @@
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+repos:
+  - repo: https://github.com/maltzj/google-style-precommit-hook
+    rev: b7e9e7fcba4a5aea463e72fe9964c14877bd8130
+    hooks:
+      - id: google-style-java
diff --git a/.pre-commit-hooks.yaml b/.pre-commit-hooks.yaml
new file mode 100644
index 00000000..1641d4ff
--- /dev/null
+++ b/.pre-commit-hooks.yaml
@@ -0,0 +1,8 @@
+# Pre-commit hook to run google-format-java right before commiting
+# Source: https://github.com/maltzj/google-style-precommit-hook
+- id: google-style-java
+  name: Google Java Code Style for Java
+  description: Formats code in Google's Java codestyle.
+  entry: ./tools/format-code.sh
+  language: script
+  files: \.java$ # We don't technically need this, as the script will filter for us, but this will allow the hook to be skipped if no Java is changed.
diff --git a/README.md b/README.md
index fbe06bcc..5dcbfdc8 100644
--- a/README.md
+++ b/README.md
@@ -39,3 +39,13 @@ Use [google-java-format](https://github.com/google/google-java-format):
 ```bash
 google-java-format --replace **/*.java # executes recursively
 ```
+
+## Pre-commit Git Hook (Tested on macOS)
+`pre-commit` is a python tool that helps to create git pre-commit hook handlers. For this project, it is used to enforce Google Java Style (via `google-java-format`) on new commits.
+
+To setup, ensure you have [`pre-commit`](https://pre-commit.com/#install) installed, then run:
+```bash
+pre-commit install
+```
+This only needs to be executed once, so that `pre-commit` can generate the script and write it to `.git/hooks/pre-commit`
+Thereafter, it should be executed right before every commit!
diff --git a/tools/format-code.sh b/tools/format-code.sh
new file mode 100644
index 00000000..da44ba37
--- /dev/null
+++ b/tools/format-code.sh
@@ -0,0 +1,13 @@
+#!/usr/bin/env sh
+mkdir -p .cache
+cd .cache
+if [ ! -f google-java-format-1.7-all-deps.jar ]
+then
+    curl -LJO "https://github.com/google/google-java-format/releases/download/google-java-format-1.7/google-java-format-1.7-all-deps.jar"
+    chmod 755 google-java-format-1.7-all-deps.jar
+fi
+cd ..
+
+changed_java_files=$(git diff --cached --name-only --diff-filter=ACMR | grep ".*java$" )
+echo $changed_java_files
+java -jar .cache/google-java-format-1.7-all-deps.jar --replace $changed_java_files

From ee1fd2926cf00d27b613a4373c7f5a4a3d42624f Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Wed, 25 Aug 2021 00:14:16 +0800
Subject: [PATCH 17/32] Fix Level-3 mark as done. (#3)

---
 .../markasdone/MarkAsDoneResponder.java       |  3 +--
 src/main/java/com/lockarhythm/tasks/Task.java |  4 ++++
 .../java/com/lockarhythm/tasks/TaskList.java  |  2 +-
 .../markasdone/TestMarkAsDoneResponder.java   | 13 ++++++++++++
 .../com/lockarhythm/tasks/TestTaskList.java   |  4 ++++
 text-ui-test/EXPECTED.TXT                     | 20 +++++++++++++++++++
 text-ui-test/input.txt                        |  3 +++
 7 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java b/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
index 182c4230..b1b2a512 100644
--- a/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
+++ b/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
@@ -8,9 +8,8 @@
 import java.util.regex.Pattern;
 
 public class MarkAsDoneResponder implements QueryRespondable {
-  private static String doneCommandPrefix = "done ";
   private TaskList list;
-  Pattern pattern = Pattern.compile(doneCommandPrefix + "(\\d+)");
+  Pattern pattern = Pattern.compile("^done (\\d+)");
 
   public MarkAsDoneResponder(TaskList list) {
     this.list = list;
diff --git a/src/main/java/com/lockarhythm/tasks/Task.java b/src/main/java/com/lockarhythm/tasks/Task.java
index 943f6749..1fae579d 100644
--- a/src/main/java/com/lockarhythm/tasks/Task.java
+++ b/src/main/java/com/lockarhythm/tasks/Task.java
@@ -13,6 +13,10 @@ public void toggleDone() {
     this.isDone = !this.isDone;
   }
 
+  public void setDone(boolean isDone) {
+    this.isDone = isDone;
+  }
+
   public String getDescription() {
     return description;
   }
diff --git a/src/main/java/com/lockarhythm/tasks/TaskList.java b/src/main/java/com/lockarhythm/tasks/TaskList.java
index 9732d032..e4e71148 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskList.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskList.java
@@ -19,7 +19,7 @@ public void add(String description) {
 
   public Task markAsDone(int index) {
     Task t = list.get(index);
-    t.toggleDone();
+    t.setDone(true);
     return t;
   }
 
diff --git a/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java b/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java
index c87d6f4c..bdc66037 100644
--- a/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java
+++ b/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java
@@ -46,4 +46,17 @@ public void testMarkAsDoneOnNonExistentItem() throws Exception {
     res = alresponder.respondTo("list");
     assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
   }
+
+  @Test
+  public void testMarkAsDoneParseCommand() throws Exception {
+    TaskList list = new TaskList();
+    MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
+    AddListResponder alresponder = new AddListResponder(list);
+
+    Response res = alresponder.respondTo("read book");
+    assertEquals("added: read book", res.getText());
+
+    res = mdresponder.respondTo("all done 10000");
+    assertNull(res);
+  }
 }
diff --git a/src/test/java/com/lockarhythm/tasks/TestTaskList.java b/src/test/java/com/lockarhythm/tasks/TestTaskList.java
index ce5d6025..eaefcdb6 100644
--- a/src/test/java/com/lockarhythm/tasks/TestTaskList.java
+++ b/src/test/java/com/lockarhythm/tasks/TestTaskList.java
@@ -15,5 +15,9 @@ public void testAddTask() throws Exception {
 
     Task task = list.markAsDone(1);
     assertEquals("can mark tasks as done", "learn bazel", task.getDescription());
+    assertTrue("task is set to done", task.isDone());
+
+    task = list.markAsDone(1);
+    assertTrue("it's an idempotent operation", task.isDone());
   }
 }
diff --git a/text-ui-test/EXPECTED.TXT b/text-ui-test/EXPECTED.TXT
index 69bbc0bb..d74f1d13 100644
--- a/text-ui-test/EXPECTED.TXT
+++ b/text-ui-test/EXPECTED.TXT
@@ -45,6 +45,26 @@
 
 	____________________________________________________________
 
+	____________________________________________________________
+	Nice! I've marked this task as done:
+		[X] return book
+
+	____________________________________________________________
+
+	____________________________________________________________
+	added: all done 1
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Here are the tasks in your list:
+	1.[X] read book
+	2.[X] return book
+	3.[ ] buy bread
+	4.[ ] all done 1
+
+	____________________________________________________________
+
 	____________________________________________________________
 	Bye. Hope to see you again soon!
 
diff --git a/text-ui-test/input.txt b/text-ui-test/input.txt
index 2cb3cf8a..8815fb5a 100644
--- a/text-ui-test/input.txt
+++ b/text-ui-test/input.txt
@@ -4,4 +4,7 @@ buy bread
 done 1
 list
 done 2
+done 2
+all done 1
+list
 bye

From 437b3859d88a2e5198d48f6f0863cd469e1a2baf Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Sun, 29 Aug 2021 13:00:51 +0800
Subject: [PATCH 18/32] More classes (#4)

- To prepare for GUI version of Duke, we extract out the core Application that accepts a UI implementation. In this MR, we implement TerminalUI for terminal/console interfaces. Later on, we can add GraphicalUI for JavaFX.
- The duke application is viewed as a REPL, where on the evaluate step, we ask the QueryInterpreter to evaluate the query inputted by the user.
- The SimpleQueryInterpreter class implements QueryInterpreter. It delegates the query to smaller QueryInterpreters, each only responding to a subset of query/commands.
- QueryResponder is renamed to QueryInterpreter.
- Response is renamed to Result. The Result class represents the result of a query interpretation.
---
 .github/workflows/workflow.yml                |  8 +--
 BUILD                                         |  4 +-
 .../lockarhythm/application/Application.java  | 28 +++++++++
 .../lockarhythm/application/TerminalDuke.java | 11 ++++
 .../java/com/lockarhythm/cmdline/Duke.java    | 62 -------------------
 .../lockarhythm/query/QueryInterpreter.java   |  5 ++
 .../Response.java => query/Result.java}       | 10 ++-
 .../query/SimpleQueryInterpreter.java         | 29 +++++++++
 .../query/addlist/AddListResponder.java       | 22 +++++++
 .../lockarhythm/query/echo/EchoResponder.java | 10 +++
 .../lockarhythm/query/exit/ExitResponder.java | 13 ++++
 .../markasdone/MarkAsDoneResponder.java       | 16 ++---
 .../responders/QueryRespondable.java          |  5 --
 .../responders/addlist/AddListResponder.java  | 22 -------
 .../responders/echo/EchoResponder.java        | 10 ---
 .../responders/exit/ExitResponder.java        | 13 ----
 .../java/com/lockarhythm/ui/TerminalUI.java   | 30 +++++++++
 src/main/java/com/lockarhythm/ui/UI.java      | 13 ++++
 .../TestTerminalDuke.java}                    |  6 +-
 .../addlist/TestAddListResponder.java         | 10 +--
 .../echo/TestEchoResponder.java               |  6 +-
 .../exit/TestExitResponder.java               |  8 +--
 .../markasdone/TestMarkAsDoneResponder.java   | 26 ++++----
 text-ui-test/runtest.sh                       |  4 +-
 24 files changed, 212 insertions(+), 159 deletions(-)
 create mode 100644 src/main/java/com/lockarhythm/application/Application.java
 create mode 100644 src/main/java/com/lockarhythm/application/TerminalDuke.java
 delete mode 100644 src/main/java/com/lockarhythm/cmdline/Duke.java
 create mode 100644 src/main/java/com/lockarhythm/query/QueryInterpreter.java
 rename src/main/java/com/lockarhythm/{responders/Response.java => query/Result.java} (58%)
 create mode 100644 src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
 create mode 100644 src/main/java/com/lockarhythm/query/addlist/AddListResponder.java
 create mode 100644 src/main/java/com/lockarhythm/query/echo/EchoResponder.java
 create mode 100644 src/main/java/com/lockarhythm/query/exit/ExitResponder.java
 rename src/main/java/com/lockarhythm/{responders => query}/markasdone/MarkAsDoneResponder.java (59%)
 delete mode 100644 src/main/java/com/lockarhythm/responders/QueryRespondable.java
 delete mode 100644 src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
 delete mode 100644 src/main/java/com/lockarhythm/responders/echo/EchoResponder.java
 delete mode 100644 src/main/java/com/lockarhythm/responders/exit/ExitResponder.java
 create mode 100644 src/main/java/com/lockarhythm/ui/TerminalUI.java
 create mode 100644 src/main/java/com/lockarhythm/ui/UI.java
 rename src/test/java/com/lockarhythm/{cmdline/TestDuke.java => application/TestTerminalDuke.java} (92%)
 rename src/test/java/com/lockarhythm/{responders => query}/addlist/TestAddListResponder.java (67%)
 rename src/test/java/com/lockarhythm/{responders => query}/echo/TestEchoResponder.java (68%)
 rename src/test/java/com/lockarhythm/{responders => query}/exit/TestExitResponder.java (68%)
 rename src/test/java/com/lockarhythm/{responders => query}/markasdone/TestMarkAsDoneResponder.java (71%)

diff --git a/.github/workflows/workflow.yml b/.github/workflows/workflow.yml
index 7fc94623..25cc361b 100644
--- a/.github/workflows/workflow.yml
+++ b/.github/workflows/workflow.yml
@@ -26,14 +26,14 @@ jobs:
 
     - name: Build JAR File
       run: |
-        "${GITHUB_WORKSPACE}/bin/bazel" build //:Duke_deploy.jar
+        "${GITHUB_WORKSPACE}/bin/bazel" build //:TerminalDuke_deploy.jar
 
     - name: "Move file to non-symlink directory (a workaround for some bug See: https://github.com/actions/upload-artifact/issues/92)"
       run: |
-       mv ${{ github.workspace }}/bazel-bin/Duke_deploy.jar ${{ github.workspace }}/Duke_deploy.jar
+       mv ${{ github.workspace }}/bazel-bin/TerminalDuke_deploy.jar ${{ github.workspace }}/TerminalDuke_deploy.jar
 
     - name: Upload JAR File
       uses: actions/upload-artifact@v2
       with:
-        name: Duke_deploy.jar
-        path: ${{ github.workspace }}/Duke_deploy.jar
+        name: TerminalDuke_deploy.jar
+        path: ${{ github.workspace }}/TerminalDuke_deploy.jar
diff --git a/BUILD b/BUILD
index ac1cceed..584ee814 100644
--- a/BUILD
+++ b/BUILD
@@ -1,7 +1,7 @@
 load("@rules_java//java:defs.bzl", "java_binary", "java_test")
 
 java_binary(
-    name = "Duke",
+    name = "TerminalDuke",
     srcs = glob([
         "src/main/java/com/lockarhythm/**/*.java",
     ]),
@@ -18,7 +18,7 @@ java_binary(
       ]),
   )
   for class_name in [
-      "TestDuke",
+      "TestTerminalDuke",
       "TestEchoResponder",
       "TestExitResponder",
       "TestAddListResponder",
diff --git a/src/main/java/com/lockarhythm/application/Application.java b/src/main/java/com/lockarhythm/application/Application.java
new file mode 100644
index 00000000..b53f39ac
--- /dev/null
+++ b/src/main/java/com/lockarhythm/application/Application.java
@@ -0,0 +1,28 @@
+package com.lockarhythm.application;
+
+import com.lockarhythm.query.QueryInterpreter;
+import com.lockarhythm.query.Result;
+import com.lockarhythm.ui.UI;
+
+abstract class Application {
+  static String logo =
+      " \t____        _        \n"
+          + "\t|  _ \\ _   _| | _____ \n"
+          + "\t| | | | | | | |/ / _ \\\n"
+          + "\t| |_| | |_| |   <  __/\n"
+          + "\t|____/ \\__,_|_|\\_\\___|\n";
+
+  public static void run(UI ui, QueryInterpreter q) {
+    Result result;
+
+    ui.print("Hello I'm\n" + logo, "What can I do for you?");
+
+    while (ui.hasNext()) {
+      result = q.interpret(ui.nextLine());
+      ui.print(result);
+      if (result.shouldExit()) {
+        break;
+      }
+    }
+  }
+}
diff --git a/src/main/java/com/lockarhythm/application/TerminalDuke.java b/src/main/java/com/lockarhythm/application/TerminalDuke.java
new file mode 100644
index 00000000..35379709
--- /dev/null
+++ b/src/main/java/com/lockarhythm/application/TerminalDuke.java
@@ -0,0 +1,11 @@
+package com.lockarhythm.application;
+
+import com.lockarhythm.query.SimpleQueryInterpreter;
+import com.lockarhythm.tasks.TaskList;
+import com.lockarhythm.ui.TerminalUI;
+
+public class TerminalDuke extends Application {
+  public static void main(String[] args) {
+    run(new TerminalUI(), new SimpleQueryInterpreter(new TaskList()));
+  }
+}
diff --git a/src/main/java/com/lockarhythm/cmdline/Duke.java b/src/main/java/com/lockarhythm/cmdline/Duke.java
deleted file mode 100644
index 8697a580..00000000
--- a/src/main/java/com/lockarhythm/cmdline/Duke.java
+++ /dev/null
@@ -1,62 +0,0 @@
-package com.lockarhythm.cmdline;
-
-import com.lockarhythm.responders.QueryRespondable;
-import com.lockarhythm.responders.Response;
-import com.lockarhythm.responders.addlist.AddListResponder;
-import com.lockarhythm.responders.exit.ExitResponder;
-import com.lockarhythm.responders.markasdone.MarkAsDoneResponder;
-import com.lockarhythm.tasks.TaskList;
-import java.util.Arrays;
-import java.util.Scanner;
-
-public class Duke {
-  static String logo =
-      " \t____        _        \n"
-          + "\t|  _ \\ _   _| | _____ \n"
-          + "\t| | | | | | | |/ / _ \\\n"
-          + "\t| |_| | |_| |   <  __/\n"
-          + "\t|____/ \\__,_|_|\\_\\___|\n";
-
-  static TaskList list = new TaskList();
-
-  static QueryRespondable[] responders = {
-    new ExitResponder(), new MarkAsDoneResponder(list), new AddListResponder(list),
-  };
-
-  private static void print(String... strings) {
-    System.out.println("\t____________________________________________________________");
-    for (String s : strings) {
-      s = Arrays.stream(s.split("\n")).map(x -> "\t" + x).reduce("", (x, y) -> x + y + "\n");
-      System.out.println(s);
-    }
-    System.out.println("\t____________________________________________________________\n");
-  }
-
-  private static Response getResponse(String query) {
-    Response res = null;
-    for (QueryRespondable responder : responders) {
-      res = responder.respondTo(query);
-      if (res != null) {
-        return res;
-      }
-    }
-    return res;
-  }
-
-  public static void main(String[] args) {
-    String line;
-    Scanner in = new Scanner(System.in);
-
-    print("Hello I'm\n" + logo, "What can I do for you?");
-
-    line = in.nextLine();
-    Response res = getResponse(line);
-    while (!res.shouldExit()) {
-      print(res.getText());
-      line = in.nextLine();
-      res = getResponse(line);
-    }
-
-    print(res.getText());
-  }
-}
diff --git a/src/main/java/com/lockarhythm/query/QueryInterpreter.java b/src/main/java/com/lockarhythm/query/QueryInterpreter.java
new file mode 100644
index 00000000..4bedb6a7
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/QueryInterpreter.java
@@ -0,0 +1,5 @@
+package com.lockarhythm.query;
+
+public interface QueryInterpreter {
+  public Result interpret(String query);
+}
diff --git a/src/main/java/com/lockarhythm/responders/Response.java b/src/main/java/com/lockarhythm/query/Result.java
similarity index 58%
rename from src/main/java/com/lockarhythm/responders/Response.java
rename to src/main/java/com/lockarhythm/query/Result.java
index c9a7f9c2..0a974d05 100644
--- a/src/main/java/com/lockarhythm/responders/Response.java
+++ b/src/main/java/com/lockarhythm/query/Result.java
@@ -1,14 +1,18 @@
-package com.lockarhythm.responders;
+package com.lockarhythm.query;
 
-public class Response {
+public class Result {
   private String text;
   private boolean shouldExit;
 
-  public Response(String text, boolean shouldExit) {
+  public Result(String text, boolean shouldExit) {
     this.text = text;
     this.shouldExit = shouldExit;
   }
 
+  public Result(String text) {
+    this(text, false);
+  }
+
   public String getText() {
     return text;
   }
diff --git a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
new file mode 100644
index 00000000..e67ab083
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
@@ -0,0 +1,29 @@
+package com.lockarhythm.query;
+
+import com.lockarhythm.query.addlist.AddListResponder;
+import com.lockarhythm.query.exit.ExitResponder;
+import com.lockarhythm.query.markasdone.MarkAsDoneResponder;
+import com.lockarhythm.tasks.TaskList;
+
+/** SimpleQueryInterpreter finds the first QueryInterpreter that responds a non-null result. */
+public class SimpleQueryInterpreter implements QueryInterpreter {
+  static QueryInterpreter[] interpreters;
+
+  public SimpleQueryInterpreter(TaskList list) {
+    QueryInterpreter[] res = {
+      new ExitResponder(), new MarkAsDoneResponder(list), new AddListResponder(list),
+    };
+    interpreters = res;
+  }
+
+  public Result interpret(String query) {
+    Result res = null;
+    for (QueryInterpreter interpreter : interpreters) {
+      res = interpreter.interpret(query);
+      if (res != null) {
+        return res;
+      }
+    }
+    return res;
+  }
+}
diff --git a/src/main/java/com/lockarhythm/query/addlist/AddListResponder.java b/src/main/java/com/lockarhythm/query/addlist/AddListResponder.java
new file mode 100644
index 00000000..31598bfd
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/addlist/AddListResponder.java
@@ -0,0 +1,22 @@
+package com.lockarhythm.query.addlist;
+
+import com.lockarhythm.query.QueryInterpreter;
+import com.lockarhythm.query.Result;
+import com.lockarhythm.tasks.TaskList;
+
+public class AddListResponder implements QueryInterpreter {
+  private TaskList list;
+
+  public AddListResponder(TaskList list) {
+    this.list = list;
+  }
+
+  public Result interpret(String query) {
+    if (query.equals("list")) {
+      return new Result("Here are the tasks in your list:\n" + list.toString());
+    }
+    // by default, adds the given query.
+    list.add(query);
+    return new Result("added: " + query);
+  }
+}
diff --git a/src/main/java/com/lockarhythm/query/echo/EchoResponder.java b/src/main/java/com/lockarhythm/query/echo/EchoResponder.java
new file mode 100644
index 00000000..7b6f8a32
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/echo/EchoResponder.java
@@ -0,0 +1,10 @@
+package com.lockarhythm.query.echo;
+
+import com.lockarhythm.query.QueryInterpreter;
+import com.lockarhythm.query.Result;
+
+public class EchoResponder implements QueryInterpreter {
+  public Result interpret(String query) {
+    return new Result(query);
+  }
+}
diff --git a/src/main/java/com/lockarhythm/query/exit/ExitResponder.java b/src/main/java/com/lockarhythm/query/exit/ExitResponder.java
new file mode 100644
index 00000000..452edcd3
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/exit/ExitResponder.java
@@ -0,0 +1,13 @@
+package com.lockarhythm.query.exit;
+
+import com.lockarhythm.query.QueryInterpreter;
+import com.lockarhythm.query.Result;
+
+public class ExitResponder implements QueryInterpreter {
+  public Result interpret(String query) {
+    if (query.equals("bye")) {
+      return new Result("Bye. Hope to see you again soon!", true);
+    }
+    return null;
+  }
+}
diff --git a/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java b/src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java
similarity index 59%
rename from src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
rename to src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java
index b1b2a512..55875739 100644
--- a/src/main/java/com/lockarhythm/responders/markasdone/MarkAsDoneResponder.java
+++ b/src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java
@@ -1,13 +1,13 @@
-package com.lockarhythm.responders.markasdone;
+package com.lockarhythm.query.markasdone;
 
-import com.lockarhythm.responders.QueryRespondable;
-import com.lockarhythm.responders.Response;
+import com.lockarhythm.query.QueryInterpreter;
+import com.lockarhythm.query.Result;
 import com.lockarhythm.tasks.Task;
 import com.lockarhythm.tasks.TaskList;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
-public class MarkAsDoneResponder implements QueryRespondable {
+public class MarkAsDoneResponder implements QueryInterpreter {
   private TaskList list;
   Pattern pattern = Pattern.compile("^done (\\d+)");
 
@@ -15,16 +15,16 @@ public MarkAsDoneResponder(TaskList list) {
     this.list = list;
   }
 
-  public Response respondTo(String query) {
+  public Result interpret(String query) {
     Matcher matcher = pattern.matcher(query);
     if (matcher.find()) {
       int i = Integer.parseInt(matcher.group(1));
       if (i > 0 && i <= list.size()) {
         Task task = list.markAsDone(i - 1);
-        return new Response("Nice! I've marked this task as done:\n\t" + task.toString(), false);
+        return new Result("Nice! I've marked this task as done:\n\t" + task.toString());
       }
-      return new Response(
-          String.format("Item %d is not on the list. I cannot mark it as done!", i), false);
+      return new Result(
+          String.format("Item %d is not on the list. I cannot mark it as done!", i));
     }
     return null;
   }
diff --git a/src/main/java/com/lockarhythm/responders/QueryRespondable.java b/src/main/java/com/lockarhythm/responders/QueryRespondable.java
deleted file mode 100644
index 2501b113..00000000
--- a/src/main/java/com/lockarhythm/responders/QueryRespondable.java
+++ /dev/null
@@ -1,5 +0,0 @@
-package com.lockarhythm.responders;
-
-public interface QueryRespondable {
-  Response respondTo(String query);
-}
diff --git a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java b/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
deleted file mode 100644
index 6253ca51..00000000
--- a/src/main/java/com/lockarhythm/responders/addlist/AddListResponder.java
+++ /dev/null
@@ -1,22 +0,0 @@
-package com.lockarhythm.responders.addlist;
-
-import com.lockarhythm.responders.QueryRespondable;
-import com.lockarhythm.responders.Response;
-import com.lockarhythm.tasks.TaskList;
-
-public class AddListResponder implements QueryRespondable {
-  private TaskList list;
-
-  public AddListResponder(TaskList list) {
-    this.list = list;
-  }
-
-  public Response respondTo(String query) {
-    if (query.equals("list")) {
-      return new Response("Here are the tasks in your list:\n" + list.toString(), false);
-    }
-    // by default, adds the given query.
-    list.add(query);
-    return new Response("added: " + query, false);
-  }
-}
diff --git a/src/main/java/com/lockarhythm/responders/echo/EchoResponder.java b/src/main/java/com/lockarhythm/responders/echo/EchoResponder.java
deleted file mode 100644
index 214acc5f..00000000
--- a/src/main/java/com/lockarhythm/responders/echo/EchoResponder.java
+++ /dev/null
@@ -1,10 +0,0 @@
-package com.lockarhythm.responders.echo;
-
-import com.lockarhythm.responders.QueryRespondable;
-import com.lockarhythm.responders.Response;
-
-public class EchoResponder implements QueryRespondable {
-  public Response respondTo(String query) {
-    return new Response(query, false);
-  }
-}
diff --git a/src/main/java/com/lockarhythm/responders/exit/ExitResponder.java b/src/main/java/com/lockarhythm/responders/exit/ExitResponder.java
deleted file mode 100644
index 0206732b..00000000
--- a/src/main/java/com/lockarhythm/responders/exit/ExitResponder.java
+++ /dev/null
@@ -1,13 +0,0 @@
-package com.lockarhythm.responders.exit;
-
-import com.lockarhythm.responders.QueryRespondable;
-import com.lockarhythm.responders.Response;
-
-public class ExitResponder implements QueryRespondable {
-  public Response respondTo(String query) {
-    if (query.equals("bye")) {
-      return new Response("Bye. Hope to see you again soon!", true);
-    }
-    return null;
-  }
-}
diff --git a/src/main/java/com/lockarhythm/ui/TerminalUI.java b/src/main/java/com/lockarhythm/ui/TerminalUI.java
new file mode 100644
index 00000000..ba7025ff
--- /dev/null
+++ b/src/main/java/com/lockarhythm/ui/TerminalUI.java
@@ -0,0 +1,30 @@
+package com.lockarhythm.ui;
+
+import com.lockarhythm.query.Result;
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class TerminalUI implements UI {
+  private static Scanner in = new Scanner(System.in);
+
+  public String nextLine() {
+    return in.nextLine();
+  }
+
+  public boolean hasNext() {
+    return in.hasNext();
+  }
+
+  public void print(String... strings) {
+    System.out.println("\t____________________________________________________________");
+    for (String s : strings) {
+      s = Arrays.stream(s.split("\n")).map(x -> "\t" + x).reduce("", (x, y) -> x + y + "\n");
+      System.out.println(s);
+    }
+    System.out.println("\t____________________________________________________________\n");
+  }
+
+  public void print(Result res) {
+    print(res.getText());
+  }
+}
diff --git a/src/main/java/com/lockarhythm/ui/UI.java b/src/main/java/com/lockarhythm/ui/UI.java
new file mode 100644
index 00000000..3a65d437
--- /dev/null
+++ b/src/main/java/com/lockarhythm/ui/UI.java
@@ -0,0 +1,13 @@
+package com.lockarhythm.ui;
+
+import com.lockarhythm.query.Result;
+
+public interface UI {
+  public String nextLine();
+
+  public boolean hasNext();
+
+  public void print(String... strings);
+
+  public void print(Result res);
+}
diff --git a/src/test/java/com/lockarhythm/cmdline/TestDuke.java b/src/test/java/com/lockarhythm/application/TestTerminalDuke.java
similarity index 92%
rename from src/test/java/com/lockarhythm/cmdline/TestDuke.java
rename to src/test/java/com/lockarhythm/application/TestTerminalDuke.java
index a2d69327..6c2c11e2 100644
--- a/src/test/java/com/lockarhythm/cmdline/TestDuke.java
+++ b/src/test/java/com/lockarhythm/application/TestTerminalDuke.java
@@ -1,4 +1,4 @@
-package com.lockarhythm.cmdline;
+package com.lockarhythm.application;
 
 import static org.junit.Assert.*;
 
@@ -8,7 +8,7 @@
 import java.io.PrintStream;
 import org.junit.Test;
 
-public class TestDuke {
+public class TestTerminalDuke {
   private final PrintStream standardOut = System.out;
   private final InputStream standardIn = System.in;
   private final ByteArrayOutputStream out = new ByteArrayOutputStream();
@@ -20,7 +20,7 @@ public void testMeetsLevel2() throws Exception {
     System.setIn(in);
     System.setOut(new PrintStream(out));
 
-    Duke.main(null);
+    TerminalDuke.main(null);
     String output = out.toString().trim();
     assertFalse(output.isEmpty());
 
diff --git a/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java b/src/test/java/com/lockarhythm/query/addlist/TestAddListResponder.java
similarity index 67%
rename from src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
rename to src/test/java/com/lockarhythm/query/addlist/TestAddListResponder.java
index 8e2d0cdb..98e5cb05 100644
--- a/src/test/java/com/lockarhythm/responders/addlist/TestAddListResponder.java
+++ b/src/test/java/com/lockarhythm/query/addlist/TestAddListResponder.java
@@ -1,8 +1,8 @@
-package com.lockarhythm.responders.addlist;
+package com.lockarhythm.query.addlist;
 
 import static org.junit.Assert.*;
 
-import com.lockarhythm.responders.Response;
+import com.lockarhythm.query.Result;
 import com.lockarhythm.tasks.TaskList;
 import org.junit.Test;
 
@@ -11,13 +11,13 @@ public class TestAddListResponder {
   public void testAddsItemsAndLists() throws Exception {
     AddListResponder responder = new AddListResponder(new TaskList());
 
-    Response res = responder.respondTo("read book");
+    Result res = responder.interpret("read book");
     assertEquals("added: read book", res.getText());
 
-    res = responder.respondTo("return book");
+    res = responder.interpret("return book");
     assertEquals("added: return book", res.getText());
 
-    res = responder.respondTo("list");
+    res = responder.interpret("list");
     assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
   }
 }
diff --git a/src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java b/src/test/java/com/lockarhythm/query/echo/TestEchoResponder.java
similarity index 68%
rename from src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java
rename to src/test/java/com/lockarhythm/query/echo/TestEchoResponder.java
index e51c34a6..a528908a 100644
--- a/src/test/java/com/lockarhythm/responders/echo/TestEchoResponder.java
+++ b/src/test/java/com/lockarhythm/query/echo/TestEchoResponder.java
@@ -1,15 +1,15 @@
-package com.lockarhythm.responders.echo;
+package com.lockarhythm.query.echo;
 
 import static org.junit.Assert.*;
 
-import com.lockarhythm.responders.Response;
+import com.lockarhythm.query.Result;
 import org.junit.Test;
 
 public class TestEchoResponder {
   @Test
   public void testEchosBackText() throws Exception {
     EchoResponder responder = new EchoResponder();
-    Response res = responder.respondTo("hello");
+    Result res = responder.interpret("hello");
 
     assertEquals("hello", res.getText());
     assertFalse(res.shouldExit());
diff --git a/src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java b/src/test/java/com/lockarhythm/query/exit/TestExitResponder.java
similarity index 68%
rename from src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java
rename to src/test/java/com/lockarhythm/query/exit/TestExitResponder.java
index b3f18bd3..da25c270 100644
--- a/src/test/java/com/lockarhythm/responders/exit/TestExitResponder.java
+++ b/src/test/java/com/lockarhythm/query/exit/TestExitResponder.java
@@ -1,15 +1,15 @@
-package com.lockarhythm.responders.exit;
+package com.lockarhythm.query.exit;
 
 import static org.junit.Assert.*;
 
-import com.lockarhythm.responders.Response;
+import com.lockarhythm.query.Result;
 import org.junit.Test;
 
 public class TestExitResponder {
   @Test
   public void testExitsOnKeyword() throws Exception {
     ExitResponder responder = new ExitResponder();
-    Response res = responder.respondTo("bye");
+    Result res = responder.interpret("bye");
 
     assertTrue(res.shouldExit());
   }
@@ -17,7 +17,7 @@ public void testExitsOnKeyword() throws Exception {
   @Test
   public void testNullOnNonkeyword() throws Exception {
     ExitResponder responder = new ExitResponder();
-    Response res = responder.respondTo("hello");
+    Result res = responder.interpret("hello");
 
     assertNull(res);
   }
diff --git a/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java b/src/test/java/com/lockarhythm/query/markasdone/TestMarkAsDoneResponder.java
similarity index 71%
rename from src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java
rename to src/test/java/com/lockarhythm/query/markasdone/TestMarkAsDoneResponder.java
index bdc66037..d82a784d 100644
--- a/src/test/java/com/lockarhythm/responders/markasdone/TestMarkAsDoneResponder.java
+++ b/src/test/java/com/lockarhythm/query/markasdone/TestMarkAsDoneResponder.java
@@ -1,9 +1,9 @@
-package com.lockarhythm.responders.markasdone;
+package com.lockarhythm.query.markasdone;
 
 import static org.junit.Assert.*;
 
-import com.lockarhythm.responders.Response;
-import com.lockarhythm.responders.addlist.AddListResponder;
+import com.lockarhythm.query.Result;
+import com.lockarhythm.query.addlist.AddListResponder;
 import com.lockarhythm.tasks.TaskList;
 import org.junit.Test;
 
@@ -14,17 +14,17 @@ public void testMarkAsDoneHappyPath() throws Exception {
     MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
     AddListResponder alresponder = new AddListResponder(list);
 
-    Response res = alresponder.respondTo("read book");
+    Result res = alresponder.interpret("read book");
     assertEquals("added: read book", res.getText());
 
-    res = alresponder.respondTo("return book");
+    res = alresponder.interpret("return book");
     assertEquals("added: return book", res.getText());
 
-    res = mdresponder.respondTo("done 1");
+    res = mdresponder.interpret("done 1");
     assertTrue(res.getText().contains("Nice! I've marked this task as done"));
     assertTrue(res.getText().contains("read book"));
 
-    res = alresponder.respondTo("list");
+    res = alresponder.interpret("list");
     assertTrue(res.getText().contains("1.[X] read book\n2.[ ] return book\n"));
   }
 
@@ -34,16 +34,16 @@ public void testMarkAsDoneOnNonExistentItem() throws Exception {
     MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
     AddListResponder alresponder = new AddListResponder(list);
 
-    Response res = alresponder.respondTo("read book");
+    Result res = alresponder.interpret("read book");
     assertEquals("added: read book", res.getText());
 
-    res = alresponder.respondTo("return book");
+    res = alresponder.interpret("return book");
     assertEquals("added: return book", res.getText());
 
-    res = mdresponder.respondTo("done 10000");
+    res = mdresponder.interpret("done 10000");
     assertTrue(res.getText().contains("Item 10000 is not on the list. I cannot mark it as done!"));
 
-    res = alresponder.respondTo("list");
+    res = alresponder.interpret("list");
     assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
   }
 
@@ -53,10 +53,10 @@ public void testMarkAsDoneParseCommand() throws Exception {
     MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
     AddListResponder alresponder = new AddListResponder(list);
 
-    Response res = alresponder.respondTo("read book");
+    Result res = alresponder.interpret("read book");
     assertEquals("added: read book", res.getText());
 
-    res = mdresponder.respondTo("all done 10000");
+    res = mdresponder.interpret("all done 10000");
     assertNull(res);
   }
 }
diff --git a/text-ui-test/runtest.sh b/text-ui-test/runtest.sh
index 220caaa7..c69a991f 100755
--- a/text-ui-test/runtest.sh
+++ b/text-ui-test/runtest.sh
@@ -13,14 +13,14 @@ then
 fi
 
 # compile the code into the bin folder, terminates if error occurred
-if ! bazel build //:Duke 
+if ! bazel build //:TerminalDuke 
 then
     echo "********** BUILD FAILURE **********"
     exit 1
 fi
 
 # run the program, feed commands from input.txt file and redirect the output to the ACTUAL.TXT
-../bazel-bin/Duke < input.txt > ACTUAL.TXT
+../bazel-bin/TerminalDuke < input.txt > ACTUAL.TXT
 
 # convert to UNIX format
 cp EXPECTED.TXT EXPECTED-UNIX.TXT

From 0605449c50a6f586fa06b12518a18804d2b90156 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Tue, 31 Aug 2021 20:59:06 +0800
Subject: [PATCH 19/32] Implement Level-4, A-Inheritance. Implement partially
 Level-5. (#5)

* Implement Level-4, A-Inheritance. Implement partially Level-5.

* Fix tests.

* Deprecate list.add method.
---
 BUILD                                         |  4 +-
 .../lockarhythm/application/Application.java  | 12 ++++--
 .../lockarhythm/application/TerminalDuke.java |  2 +-
 .../lockarhythm/query/AddedTaskResult.java    | 22 ++++++++++
 .../query/RegexQueryInterpreter.java          | 33 +++++++++++++++
 .../query/SimpleQueryInterpreter.java         | 14 +++++--
 .../query/deadline/DeadlineResponder.java     | 24 +++++++++++
 .../query/event/EventResponder.java           | 24 +++++++++++
 .../ListResponder.java}                       | 11 +++--
 .../query/markasdone/MarkAsDoneResponder.java | 29 ++++++-------
 .../lockarhythm/query/todo/TodoResponder.java | 24 +++++++++++
 .../com/lockarhythm/tasks/DeadlineTask.java   | 20 +++++++++
 .../java/com/lockarhythm/tasks/EventTask.java | 20 +++++++++
 src/main/java/com/lockarhythm/tasks/Task.java |  6 ++-
 .../java/com/lockarhythm/tasks/TaskList.java  | 18 +++++++-
 .../java/com/lockarhythm/tasks/TodoTask.java  | 12 ++++++
 .../java/com/lockarhythm/ui/TerminalUI.java   |  2 +-
 .../application/TestTerminalDuke.java         | 10 ++---
 .../query/addlist/TestAddListResponder.java   | 23 -----------
 .../query/list/TestListResponder.java         | 21 ++++++++++
 .../markasdone/TestMarkAsDoneResponder.java   | 39 ++++++------------
 .../com/lockarhythm/tasks/TestTaskList.java   |  4 +-
 .../{TestTask.java => TestTodoTask.java}      |  4 +-
 text-ui-test/EXPECTED.TXT                     | 41 ++++++++++++-------
 text-ui-test/input.txt                        |  9 ++--
 25 files changed, 315 insertions(+), 113 deletions(-)
 create mode 100644 src/main/java/com/lockarhythm/query/AddedTaskResult.java
 create mode 100644 src/main/java/com/lockarhythm/query/RegexQueryInterpreter.java
 create mode 100644 src/main/java/com/lockarhythm/query/deadline/DeadlineResponder.java
 create mode 100644 src/main/java/com/lockarhythm/query/event/EventResponder.java
 rename src/main/java/com/lockarhythm/query/{addlist/AddListResponder.java => list/ListResponder.java} (58%)
 create mode 100644 src/main/java/com/lockarhythm/query/todo/TodoResponder.java
 create mode 100644 src/main/java/com/lockarhythm/tasks/DeadlineTask.java
 create mode 100644 src/main/java/com/lockarhythm/tasks/EventTask.java
 create mode 100644 src/main/java/com/lockarhythm/tasks/TodoTask.java
 delete mode 100644 src/test/java/com/lockarhythm/query/addlist/TestAddListResponder.java
 create mode 100644 src/test/java/com/lockarhythm/query/list/TestListResponder.java
 rename src/test/java/com/lockarhythm/tasks/{TestTask.java => TestTodoTask.java} (74%)

diff --git a/BUILD b/BUILD
index 584ee814..ff824a2b 100644
--- a/BUILD
+++ b/BUILD
@@ -21,9 +21,9 @@ java_binary(
       "TestTerminalDuke",
       "TestEchoResponder",
       "TestExitResponder",
-      "TestAddListResponder",
+      "TestListResponder",
       "TestMarkAsDoneResponder",
-      "TestTask",
+      "TestTodoTask",
       "TestTaskList",
   ]
 ]
diff --git a/src/main/java/com/lockarhythm/application/Application.java b/src/main/java/com/lockarhythm/application/Application.java
index b53f39ac..0f5db708 100644
--- a/src/main/java/com/lockarhythm/application/Application.java
+++ b/src/main/java/com/lockarhythm/application/Application.java
@@ -18,10 +18,14 @@ public static void run(UI ui, QueryInterpreter q) {
     ui.print("Hello I'm\n" + logo, "What can I do for you?");
 
     while (ui.hasNext()) {
-      result = q.interpret(ui.nextLine());
-      ui.print(result);
-      if (result.shouldExit()) {
-        break;
+      try {
+        result = q.interpret(ui.nextLine());
+        ui.print(result);
+        if (result.shouldExit()) {
+          break;
+        }
+      } catch (NullPointerException e) {
+        ui.print("Sorry, I don't understand that yet!");
       }
     }
   }
diff --git a/src/main/java/com/lockarhythm/application/TerminalDuke.java b/src/main/java/com/lockarhythm/application/TerminalDuke.java
index 35379709..6cd3823d 100644
--- a/src/main/java/com/lockarhythm/application/TerminalDuke.java
+++ b/src/main/java/com/lockarhythm/application/TerminalDuke.java
@@ -4,7 +4,7 @@
 import com.lockarhythm.tasks.TaskList;
 import com.lockarhythm.ui.TerminalUI;
 
-public class TerminalDuke extends Application {
+final class TerminalDuke extends Application {
   public static void main(String[] args) {
     run(new TerminalUI(), new SimpleQueryInterpreter(new TaskList()));
   }
diff --git a/src/main/java/com/lockarhythm/query/AddedTaskResult.java b/src/main/java/com/lockarhythm/query/AddedTaskResult.java
new file mode 100644
index 00000000..dd000a56
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/AddedTaskResult.java
@@ -0,0 +1,22 @@
+package com.lockarhythm.query;
+
+import com.lockarhythm.tasks.Task;
+import com.lockarhythm.tasks.TaskList;
+
+public class AddedTaskResult extends Result {
+  private Task task;
+  private int size; // the max size on add
+
+  public AddedTaskResult(Task task, int size) {
+    super(task.toString());
+    this.task = task;
+    this.size = size;
+  }
+
+  @Override
+  public String getText() {
+    return String.format(
+          "Got it. I've added this task:\n\t%s\nNow you have %d tasks in the list.",
+          task, size);
+  }
+}
diff --git a/src/main/java/com/lockarhythm/query/RegexQueryInterpreter.java b/src/main/java/com/lockarhythm/query/RegexQueryInterpreter.java
new file mode 100644
index 00000000..8c5484f2
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/RegexQueryInterpreter.java
@@ -0,0 +1,33 @@
+package com.lockarhythm.query;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public abstract class RegexQueryInterpreter implements QueryInterpreter {
+  private Pattern pattern;
+
+  public RegexQueryInterpreter() {
+    pattern = Pattern.compile(commandRegex());
+  }
+
+  public Result interpret(String query) {
+    Matcher matcher = pattern.matcher(query);
+    if (matcher.find()) {
+      return onMatch(toGroupStrings(matcher));
+    }
+    return null;
+  }
+
+  private String[] toGroupStrings(Matcher matcher) {
+    String[] groups = new String[matcher.groupCount()+1];
+    for (int i = 0; i <= matcher.groupCount(); i++) {
+      groups[i] = matcher.group(i);
+    }
+    return groups;
+  }
+
+  // onMatch is called when regexp pattern matches. The regexp capturing groups is passed as arguments.
+  public abstract Result onMatch(String[] groups);
+
+  protected abstract String commandRegex();
+}
diff --git a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
index e67ab083..3bd098f1 100644
--- a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
+++ b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
@@ -1,17 +1,25 @@
 package com.lockarhythm.query;
 
-import com.lockarhythm.query.addlist.AddListResponder;
+import com.lockarhythm.query.list.ListResponder;
+import com.lockarhythm.query.deadline.DeadlineResponder;
+import com.lockarhythm.query.event.EventResponder;
 import com.lockarhythm.query.exit.ExitResponder;
 import com.lockarhythm.query.markasdone.MarkAsDoneResponder;
+import com.lockarhythm.query.todo.TodoResponder;
 import com.lockarhythm.tasks.TaskList;
 
 /** SimpleQueryInterpreter finds the first QueryInterpreter that responds a non-null result. */
-public class SimpleQueryInterpreter implements QueryInterpreter {
+public final class SimpleQueryInterpreter implements QueryInterpreter {
   static QueryInterpreter[] interpreters;
 
   public SimpleQueryInterpreter(TaskList list) {
     QueryInterpreter[] res = {
-      new ExitResponder(), new MarkAsDoneResponder(list), new AddListResponder(list),
+      new ExitResponder(),
+      new MarkAsDoneResponder(list),
+      new TodoResponder(list),
+      new ListResponder(list),
+      new DeadlineResponder(list),
+      new EventResponder(list),
     };
     interpreters = res;
   }
diff --git a/src/main/java/com/lockarhythm/query/deadline/DeadlineResponder.java b/src/main/java/com/lockarhythm/query/deadline/DeadlineResponder.java
new file mode 100644
index 00000000..3bfabe5a
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/deadline/DeadlineResponder.java
@@ -0,0 +1,24 @@
+package com.lockarhythm.query.deadline;
+
+import com.lockarhythm.query.RegexQueryInterpreter;
+import com.lockarhythm.query.Result;
+import com.lockarhythm.query.AddedTaskResult;
+import com.lockarhythm.tasks.Task;
+import com.lockarhythm.tasks.TaskList;
+
+public class DeadlineResponder extends RegexQueryInterpreter {
+  private TaskList list;
+
+  public DeadlineResponder(TaskList list) {
+    this.list = list;
+  }
+
+  protected String commandRegex() {
+    return "^deadline (.+) \\/by (.+)";
+  }
+
+  public Result onMatch(String[] groups) {
+    Task task = list.addDeadlineTask(groups[1], groups[2]);
+    return new AddedTaskResult(task, list.size());
+  }
+}
diff --git a/src/main/java/com/lockarhythm/query/event/EventResponder.java b/src/main/java/com/lockarhythm/query/event/EventResponder.java
new file mode 100644
index 00000000..d69a73bf
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/event/EventResponder.java
@@ -0,0 +1,24 @@
+package com.lockarhythm.query.event;
+
+import com.lockarhythm.query.RegexQueryInterpreter;
+import com.lockarhythm.query.Result;
+import com.lockarhythm.query.AddedTaskResult;
+import com.lockarhythm.tasks.Task;
+import com.lockarhythm.tasks.TaskList;
+
+public class EventResponder extends RegexQueryInterpreter {
+  private TaskList list;
+
+  public EventResponder(TaskList list) {
+    this.list = list;
+  }
+
+  protected String commandRegex() {
+    return "^event (.+) \\/at (.+)";
+  }
+
+  public Result onMatch(String[] groups) {
+    Task task = list.addEventTask(groups[1], groups[2]);
+    return new AddedTaskResult(task, list.size());
+  }
+}
diff --git a/src/main/java/com/lockarhythm/query/addlist/AddListResponder.java b/src/main/java/com/lockarhythm/query/list/ListResponder.java
similarity index 58%
rename from src/main/java/com/lockarhythm/query/addlist/AddListResponder.java
rename to src/main/java/com/lockarhythm/query/list/ListResponder.java
index 31598bfd..13077612 100644
--- a/src/main/java/com/lockarhythm/query/addlist/AddListResponder.java
+++ b/src/main/java/com/lockarhythm/query/list/ListResponder.java
@@ -1,13 +1,14 @@
-package com.lockarhythm.query.addlist;
+package com.lockarhythm.query.list;
 
 import com.lockarhythm.query.QueryInterpreter;
 import com.lockarhythm.query.Result;
+import com.lockarhythm.tasks.Task;
 import com.lockarhythm.tasks.TaskList;
 
-public class AddListResponder implements QueryInterpreter {
+public final class ListResponder implements QueryInterpreter {
   private TaskList list;
 
-  public AddListResponder(TaskList list) {
+  public ListResponder(TaskList list) {
     this.list = list;
   }
 
@@ -15,8 +16,6 @@ public Result interpret(String query) {
     if (query.equals("list")) {
       return new Result("Here are the tasks in your list:\n" + list.toString());
     }
-    // by default, adds the given query.
-    list.add(query);
-    return new Result("added: " + query);
+    return null;
   }
 }
diff --git a/src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java b/src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java
index 55875739..c9c330b4 100644
--- a/src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java
+++ b/src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java
@@ -1,31 +1,28 @@
 package com.lockarhythm.query.markasdone;
 
-import com.lockarhythm.query.QueryInterpreter;
+import com.lockarhythm.query.RegexQueryInterpreter;
 import com.lockarhythm.query.Result;
 import com.lockarhythm.tasks.Task;
 import com.lockarhythm.tasks.TaskList;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
-public class MarkAsDoneResponder implements QueryInterpreter {
+public class MarkAsDoneResponder extends RegexQueryInterpreter {
   private TaskList list;
-  Pattern pattern = Pattern.compile("^done (\\d+)");
 
   public MarkAsDoneResponder(TaskList list) {
     this.list = list;
   }
 
-  public Result interpret(String query) {
-    Matcher matcher = pattern.matcher(query);
-    if (matcher.find()) {
-      int i = Integer.parseInt(matcher.group(1));
-      if (i > 0 && i <= list.size()) {
-        Task task = list.markAsDone(i - 1);
-        return new Result("Nice! I've marked this task as done:\n\t" + task.toString());
-      }
-      return new Result(
-          String.format("Item %d is not on the list. I cannot mark it as done!", i));
+  protected String commandRegex() {
+    return "^done (\\d+)";
+  }
+
+  public Result onMatch(String[] groups) {
+    int i = Integer.parseInt(groups[1]);
+    try {
+      Task task = list.markAsDone(i - 1);
+      return new Result("Nice! I've marked this task as done:\n\t" + task.toString());
+    } catch(IndexOutOfBoundsException e) {
+      return new Result(String.format("Item %d is not on the list. I cannot mark it as done!", i));
     }
-    return null;
   }
 }
diff --git a/src/main/java/com/lockarhythm/query/todo/TodoResponder.java b/src/main/java/com/lockarhythm/query/todo/TodoResponder.java
new file mode 100644
index 00000000..1725ffc0
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/todo/TodoResponder.java
@@ -0,0 +1,24 @@
+package com.lockarhythm.query.todo;
+
+import com.lockarhythm.query.RegexQueryInterpreter;
+import com.lockarhythm.query.AddedTaskResult;
+import com.lockarhythm.query.Result;
+import com.lockarhythm.tasks.Task;
+import com.lockarhythm.tasks.TaskList;
+
+public class TodoResponder extends RegexQueryInterpreter {
+  private TaskList list;
+
+  public TodoResponder(TaskList list) {
+    this.list = list;
+  }
+
+  protected String commandRegex() {
+    return "^todo (.+)";
+  }
+
+  public Result onMatch(String[] groups) {
+    Task task = list.addTodoTask(groups[1]);
+    return new AddedTaskResult(task, list.size());
+  }
+}
diff --git a/src/main/java/com/lockarhythm/tasks/DeadlineTask.java b/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
new file mode 100644
index 00000000..0973e7ef
--- /dev/null
+++ b/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
@@ -0,0 +1,20 @@
+package com.lockarhythm.tasks;
+
+final class DeadlineTask extends Task {
+  private String by;
+
+  public DeadlineTask(String description, String by) {
+    super(description);
+    this.by = by;
+  }
+
+  @Override
+  protected String getTaskTypeIcon() {
+    return "D";
+  }
+
+  @Override
+  public String toString() {
+    return String.format("%s (by: %s)", super.toString(), by);
+  }
+}
diff --git a/src/main/java/com/lockarhythm/tasks/EventTask.java b/src/main/java/com/lockarhythm/tasks/EventTask.java
new file mode 100644
index 00000000..a2910830
--- /dev/null
+++ b/src/main/java/com/lockarhythm/tasks/EventTask.java
@@ -0,0 +1,20 @@
+package com.lockarhythm.tasks;
+
+final class EventTask extends Task {
+  private String at;
+
+  public EventTask(String description, String at) {
+    super(description);
+    this.at = at;
+  }
+
+  @Override
+  protected String getTaskTypeIcon() {
+    return "E";
+  }
+
+  @Override
+  public String toString() {
+    return String.format("%s (at: %s)", super.toString(), at);
+  }
+}
diff --git a/src/main/java/com/lockarhythm/tasks/Task.java b/src/main/java/com/lockarhythm/tasks/Task.java
index 1fae579d..fb554905 100644
--- a/src/main/java/com/lockarhythm/tasks/Task.java
+++ b/src/main/java/com/lockarhythm/tasks/Task.java
@@ -1,6 +1,6 @@
 package com.lockarhythm.tasks;
 
-public class Task {
+public abstract class Task {
   private String description;
   private boolean isDone;
 
@@ -29,8 +29,10 @@ private String getDoneIcon() {
     return isDone ? "X" : " ";
   }
 
+  protected abstract String getTaskTypeIcon();
+
   @Override
   public String toString() {
-    return String.format("[%s] %s", getDoneIcon(), description);
+    return String.format("[%s][%s] %s", getTaskTypeIcon(), getDoneIcon(), description);
   }
 }
diff --git a/src/main/java/com/lockarhythm/tasks/TaskList.java b/src/main/java/com/lockarhythm/tasks/TaskList.java
index e4e71148..6b13544f 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskList.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskList.java
@@ -13,8 +13,22 @@ public int size() {
     return list.size();
   }
 
-  public void add(String description) {
-    list.add(new Task(description));
+  public TodoTask addTodoTask(String description) {
+    TodoTask task = new TodoTask(description);
+    list.add(task);
+    return task;
+  }
+
+  public DeadlineTask addDeadlineTask(String description, String by) {
+    DeadlineTask task = new DeadlineTask(description, by);
+    list.add(task);
+    return task;
+  }
+
+  public EventTask addEventTask(String description, String at) {
+    EventTask task = new EventTask(description, at);
+    list.add(task);
+    return task;
   }
 
   public Task markAsDone(int index) {
diff --git a/src/main/java/com/lockarhythm/tasks/TodoTask.java b/src/main/java/com/lockarhythm/tasks/TodoTask.java
new file mode 100644
index 00000000..38b1e9cc
--- /dev/null
+++ b/src/main/java/com/lockarhythm/tasks/TodoTask.java
@@ -0,0 +1,12 @@
+package com.lockarhythm.tasks;
+
+public final class TodoTask extends Task {
+  public TodoTask(String description) {
+    super(description);
+  }
+
+  @Override
+  protected String getTaskTypeIcon() {
+    return "T";
+  }
+}
diff --git a/src/main/java/com/lockarhythm/ui/TerminalUI.java b/src/main/java/com/lockarhythm/ui/TerminalUI.java
index ba7025ff..4c60aad5 100644
--- a/src/main/java/com/lockarhythm/ui/TerminalUI.java
+++ b/src/main/java/com/lockarhythm/ui/TerminalUI.java
@@ -4,7 +4,7 @@
 import java.util.Arrays;
 import java.util.Scanner;
 
-public class TerminalUI implements UI {
+public final class TerminalUI implements UI {
   private static Scanner in = new Scanner(System.in);
 
   public String nextLine() {
diff --git a/src/test/java/com/lockarhythm/application/TestTerminalDuke.java b/src/test/java/com/lockarhythm/application/TestTerminalDuke.java
index 6c2c11e2..11d2f9b5 100644
--- a/src/test/java/com/lockarhythm/application/TestTerminalDuke.java
+++ b/src/test/java/com/lockarhythm/application/TestTerminalDuke.java
@@ -13,7 +13,7 @@ public class TestTerminalDuke {
   private final InputStream standardIn = System.in;
   private final ByteArrayOutputStream out = new ByteArrayOutputStream();
   private final ByteArrayInputStream in =
-      new ByteArrayInputStream("read book\nreturn book\nlist\nbye".getBytes());
+      new ByteArrayInputStream("todo read book\ntodo return book\nlist\nbye".getBytes());
 
   @Test
   public void testMeetsLevel2() throws Exception {
@@ -24,10 +24,10 @@ public void testMeetsLevel2() throws Exception {
     String output = out.toString().trim();
     assertFalse(output.isEmpty());
 
-    assertTrue("it adds the 1st item", output.contains("added: read book"));
-    assertTrue("it adds the 2nd item", output.contains("added: return book"));
-    assertTrue("it lists the items", output.contains("1.[ ] read book"));
-    assertTrue("it lists the items", output.contains("2.[ ] return book"));
+    assertTrue("it adds the 1st item", output.contains("Now you have 1 tasks in the list"));
+    assertTrue("it adds the 2nd item", output.contains("Now you have 2 tasks in the list"));
+    assertTrue("it lists the items", output.contains("1.[T][ ] read book"));
+    assertTrue("it lists the items", output.contains("2.[T][ ] return book"));
     assertTrue("it exits", output.contains("Bye. Hope to see you again soon!"));
 
     System.setOut(standardOut);
diff --git a/src/test/java/com/lockarhythm/query/addlist/TestAddListResponder.java b/src/test/java/com/lockarhythm/query/addlist/TestAddListResponder.java
deleted file mode 100644
index 98e5cb05..00000000
--- a/src/test/java/com/lockarhythm/query/addlist/TestAddListResponder.java
+++ /dev/null
@@ -1,23 +0,0 @@
-package com.lockarhythm.query.addlist;
-
-import static org.junit.Assert.*;
-
-import com.lockarhythm.query.Result;
-import com.lockarhythm.tasks.TaskList;
-import org.junit.Test;
-
-public class TestAddListResponder {
-  @Test
-  public void testAddsItemsAndLists() throws Exception {
-    AddListResponder responder = new AddListResponder(new TaskList());
-
-    Result res = responder.interpret("read book");
-    assertEquals("added: read book", res.getText());
-
-    res = responder.interpret("return book");
-    assertEquals("added: return book", res.getText());
-
-    res = responder.interpret("list");
-    assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
-  }
-}
diff --git a/src/test/java/com/lockarhythm/query/list/TestListResponder.java b/src/test/java/com/lockarhythm/query/list/TestListResponder.java
new file mode 100644
index 00000000..03f7c638
--- /dev/null
+++ b/src/test/java/com/lockarhythm/query/list/TestListResponder.java
@@ -0,0 +1,21 @@
+package com.lockarhythm.query.list;
+
+import static org.junit.Assert.*;
+
+import com.lockarhythm.query.Result;
+import com.lockarhythm.tasks.TaskList;
+import org.junit.Test;
+
+public class TestListResponder {
+  @Test
+  public void testAddsItemsAndLists() throws Exception {
+    TaskList list = new TaskList();
+    ListResponder responder = new ListResponder(list);
+
+    list.addTodoTask("read book");
+    list.addTodoTask("return book");
+
+    Result res = responder.interpret("list");
+    assertTrue(res.getText().contains("1.[T][ ] read book\n2.[T][ ] return book\n"));
+  }
+}
diff --git a/src/test/java/com/lockarhythm/query/markasdone/TestMarkAsDoneResponder.java b/src/test/java/com/lockarhythm/query/markasdone/TestMarkAsDoneResponder.java
index d82a784d..9655d533 100644
--- a/src/test/java/com/lockarhythm/query/markasdone/TestMarkAsDoneResponder.java
+++ b/src/test/java/com/lockarhythm/query/markasdone/TestMarkAsDoneResponder.java
@@ -3,7 +3,6 @@
 import static org.junit.Assert.*;
 
 import com.lockarhythm.query.Result;
-import com.lockarhythm.query.addlist.AddListResponder;
 import com.lockarhythm.tasks.TaskList;
 import org.junit.Test;
 
@@ -11,52 +10,40 @@ public class TestMarkAsDoneResponder {
   @Test
   public void testMarkAsDoneHappyPath() throws Exception {
     TaskList list = new TaskList();
-    MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
-    AddListResponder alresponder = new AddListResponder(list);
+    MarkAsDoneResponder responder = new MarkAsDoneResponder(list);
 
-    Result res = alresponder.interpret("read book");
-    assertEquals("added: read book", res.getText());
+    list.addTodoTask("read book");
+    list.addTodoTask("return book");
 
-    res = alresponder.interpret("return book");
-    assertEquals("added: return book", res.getText());
-
-    res = mdresponder.interpret("done 1");
+    Result res = responder.interpret("done 1");
     assertTrue(res.getText().contains("Nice! I've marked this task as done"));
     assertTrue(res.getText().contains("read book"));
 
-    res = alresponder.interpret("list");
-    assertTrue(res.getText().contains("1.[X] read book\n2.[ ] return book\n"));
+    assertTrue(list.toString().contains("1.[T][X] read book\n2.[T][ ] return book\n"));
   }
 
   @Test
   public void testMarkAsDoneOnNonExistentItem() throws Exception {
     TaskList list = new TaskList();
-    MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
-    AddListResponder alresponder = new AddListResponder(list);
-
-    Result res = alresponder.interpret("read book");
-    assertEquals("added: read book", res.getText());
+    MarkAsDoneResponder responder = new MarkAsDoneResponder(list);
 
-    res = alresponder.interpret("return book");
-    assertEquals("added: return book", res.getText());
+    list.addTodoTask("read book");
+    list.addTodoTask("return book");
 
-    res = mdresponder.interpret("done 10000");
+    Result res = responder.interpret("done 10000");
     assertTrue(res.getText().contains("Item 10000 is not on the list. I cannot mark it as done!"));
 
-    res = alresponder.interpret("list");
-    assertTrue(res.getText().contains("1.[ ] read book\n2.[ ] return book\n"));
+    assertTrue(list.toString().contains("1.[T][ ] read book\n2.[T][ ] return book\n"));
   }
 
   @Test
   public void testMarkAsDoneParseCommand() throws Exception {
     TaskList list = new TaskList();
-    MarkAsDoneResponder mdresponder = new MarkAsDoneResponder(list);
-    AddListResponder alresponder = new AddListResponder(list);
+    MarkAsDoneResponder responder = new MarkAsDoneResponder(list);
 
-    Result res = alresponder.interpret("read book");
-    assertEquals("added: read book", res.getText());
+    list.addTodoTask("read book");
 
-    res = mdresponder.interpret("all done 10000");
+    Result res = responder.interpret("all done 10000");
     assertNull(res);
   }
 }
diff --git a/src/test/java/com/lockarhythm/tasks/TestTaskList.java b/src/test/java/com/lockarhythm/tasks/TestTaskList.java
index eaefcdb6..5c98bd5c 100644
--- a/src/test/java/com/lockarhythm/tasks/TestTaskList.java
+++ b/src/test/java/com/lockarhythm/tasks/TestTaskList.java
@@ -9,8 +9,8 @@ public class TestTaskList {
   public void testAddTask() throws Exception {
     TaskList list = new TaskList();
 
-    list.add("learn useful libraries in java");
-    list.add("learn bazel");
+    list.addTodoTask("learn useful libraries in java");
+    list.addTodoTask("learn bazel");
     assertEquals("has correct number of items", 2, list.size());
 
     Task task = list.markAsDone(1);
diff --git a/src/test/java/com/lockarhythm/tasks/TestTask.java b/src/test/java/com/lockarhythm/tasks/TestTodoTask.java
similarity index 74%
rename from src/test/java/com/lockarhythm/tasks/TestTask.java
rename to src/test/java/com/lockarhythm/tasks/TestTodoTask.java
index f70783c3..a9fb2591 100644
--- a/src/test/java/com/lockarhythm/tasks/TestTask.java
+++ b/src/test/java/com/lockarhythm/tasks/TestTodoTask.java
@@ -4,10 +4,10 @@
 
 import org.junit.Test;
 
-public class TestTask {
+public class TestTodoTask {
   @Test
   public void testToggleDone() throws Exception {
-    Task task = new Task("learn java well");
+    TodoTask task = new TodoTask("learn java well");
 
     task.toggleDone();
     assertTrue("task should be done", task.isDone());
diff --git a/text-ui-test/EXPECTED.TXT b/text-ui-test/EXPECTED.TXT
index d74f1d13..8411ae79 100644
--- a/text-ui-test/EXPECTED.TXT
+++ b/text-ui-test/EXPECTED.TXT
@@ -11,57 +11,70 @@
 	____________________________________________________________
 
 	____________________________________________________________
-	added: read book
+	Got it. I've added this task:
+		[T][ ] borrow book
+	Now you have 1 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
-	added: return book
+	Got it. I've added this task:
+		[D][ ] return book (by: 10pm)
+	Now you have 2 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
-	added: buy bread
+	Got it. I've added this task:
+		[E][ ] buy bread (at: Sunday 11pm)
+	Now you have 3 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Nice! I've marked this task as done:
-		[X] read book
+		[T][X] borrow book
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Here are the tasks in your list:
-	1.[X] read book
-	2.[ ] return book
-	3.[ ] buy bread
+	1.[T][X] borrow book
+	2.[D][ ] return book (by: 10pm)
+	3.[E][ ] buy bread (at: Sunday 11pm)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Nice! I've marked this task as done:
-		[X] return book
+		[D][X] return book (by: 10pm)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Nice! I've marked this task as done:
-		[X] return book
+		[D][X] return book (by: 10pm)
 
 	____________________________________________________________
 
 	____________________________________________________________
-	added: all done 1
+	Got it. I've added this task:
+		[T][ ] done 1
+	Now you have 4 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Here are the tasks in your list:
-	1.[X] read book
-	2.[X] return book
-	3.[ ] buy bread
-	4.[ ] all done 1
+	1.[T][X] borrow book
+	2.[D][X] return book (by: 10pm)
+	3.[E][ ] buy bread (at: Sunday 11pm)
+	4.[T][ ] done 1
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Sorry, I don't understand that yet!
 
 	____________________________________________________________
 
diff --git a/text-ui-test/input.txt b/text-ui-test/input.txt
index 8815fb5a..23404b0a 100644
--- a/text-ui-test/input.txt
+++ b/text-ui-test/input.txt
@@ -1,10 +1,11 @@
-read book
-return book
-buy bread
+todo borrow book
+deadline return book /by 10pm
+event buy bread /at Sunday 11pm
 done 1
 list
 done 2
 done 2
-all done 1
+todo done 1
 list
+a-command-that-duke-doesnt-know
 bye

From 99c1e95d727e49d405602b7a97ed2bb6b93643ae Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Tue, 31 Aug 2021 21:17:43 +0800
Subject: [PATCH 20/32] Implement Level-5 and A-Exceptions. Throw DukeException
 instead of returning null. (#6)

---
 src/main/java/com/lockarhythm/application/Application.java | 3 ++-
 src/main/java/com/lockarhythm/query/DukeException.java     | 4 ++++
 src/main/java/com/lockarhythm/query/QueryInterpreter.java  | 2 +-
 .../java/com/lockarhythm/query/SimpleQueryInterpreter.java | 7 +++----
 4 files changed, 10 insertions(+), 6 deletions(-)
 create mode 100644 src/main/java/com/lockarhythm/query/DukeException.java

diff --git a/src/main/java/com/lockarhythm/application/Application.java b/src/main/java/com/lockarhythm/application/Application.java
index 0f5db708..ce327aee 100644
--- a/src/main/java/com/lockarhythm/application/Application.java
+++ b/src/main/java/com/lockarhythm/application/Application.java
@@ -1,5 +1,6 @@
 package com.lockarhythm.application;
 
+import com.lockarhythm.query.DukeException;
 import com.lockarhythm.query.QueryInterpreter;
 import com.lockarhythm.query.Result;
 import com.lockarhythm.ui.UI;
@@ -24,7 +25,7 @@ public static void run(UI ui, QueryInterpreter q) {
         if (result.shouldExit()) {
           break;
         }
-      } catch (NullPointerException e) {
+      } catch (DukeException e) {
         ui.print("Sorry, I don't understand that yet!");
       }
     }
diff --git a/src/main/java/com/lockarhythm/query/DukeException.java b/src/main/java/com/lockarhythm/query/DukeException.java
new file mode 100644
index 00000000..a6756f5e
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/DukeException.java
@@ -0,0 +1,4 @@
+package com.lockarhythm.query;
+
+public class DukeException extends Exception {
+}
diff --git a/src/main/java/com/lockarhythm/query/QueryInterpreter.java b/src/main/java/com/lockarhythm/query/QueryInterpreter.java
index 4bedb6a7..9d856d31 100644
--- a/src/main/java/com/lockarhythm/query/QueryInterpreter.java
+++ b/src/main/java/com/lockarhythm/query/QueryInterpreter.java
@@ -1,5 +1,5 @@
 package com.lockarhythm.query;
 
 public interface QueryInterpreter {
-  public Result interpret(String query);
+  public Result interpret(String query) throws DukeException;
 }
diff --git a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
index 3bd098f1..a8a5342c 100644
--- a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
+++ b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
@@ -24,14 +24,13 @@ public SimpleQueryInterpreter(TaskList list) {
     interpreters = res;
   }
 
-  public Result interpret(String query) {
-    Result res = null;
+  public Result interpret(String query) throws DukeException {
     for (QueryInterpreter interpreter : interpreters) {
-      res = interpreter.interpret(query);
+      Result res = interpreter.interpret(query);
       if (res != null) {
         return res;
       }
     }
-    return res;
+    throw new DukeException();
   }
 }

From 52c3d42d71499adc4e2070c8d943d2bcdcc4b3ea Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Tue, 31 Aug 2021 23:24:47 +0800
Subject: [PATCH 21/32] Add gif demo in README

---
 README.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/README.md b/README.md
index 5dcbfdc8..e260776c 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,10 @@
 
 This is a project template for a greenfield Java project. It's named after the Java mascot _Duke_. Given below are instructions on how to use it.
 
+## Demo
+![output](https://user-images.githubusercontent.com/88638946/131530452-cbe5ab59-9e43-4c08-affe-f9fdf2c75427.gif)
+
+
 ## Build
 Prerequisites: Have `bazel` installed.
 

From 27456d4cce74ca24731517df09f41efbafaeebd6 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Tue, 21 Sep 2021 20:10:33 +0800
Subject: [PATCH 22/32] Implement delete Level-6 (#8)

---
 .../lockarhythm/query/DeletedTaskResult.java  | 20 +++++++++++++
 .../query/SimpleQueryInterpreter.java         |  2 ++
 .../query/delete/DeleteResponder.java         | 29 +++++++++++++++++++
 .../java/com/lockarhythm/tasks/TaskList.java  |  4 +++
 text-ui-test/EXPECTED.TXT                     | 12 ++++++++
 text-ui-test/input.txt                        |  2 ++
 6 files changed, 69 insertions(+)
 create mode 100644 src/main/java/com/lockarhythm/query/DeletedTaskResult.java
 create mode 100644 src/main/java/com/lockarhythm/query/delete/DeleteResponder.java

diff --git a/src/main/java/com/lockarhythm/query/DeletedTaskResult.java b/src/main/java/com/lockarhythm/query/DeletedTaskResult.java
new file mode 100644
index 00000000..128ac60a
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/DeletedTaskResult.java
@@ -0,0 +1,20 @@
+package com.lockarhythm.query;
+
+import com.lockarhythm.tasks.Task;
+
+public class DeletedTaskResult extends Result {
+  private Task task;
+  private int size; // new size after deletion
+
+  public DeletedTaskResult(Task task, int size) {
+    super(task.toString());
+    this.task = task;
+    this.size = size;
+  }
+
+  @Override
+  public String getText() {
+    return String.format(
+        "Noted. I've removed this task:\n\t%s\nNow you have %d tasks in the list.", task, size);
+  }
+}
diff --git a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
index a8a5342c..64d03e4f 100644
--- a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
+++ b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
@@ -6,6 +6,7 @@
 import com.lockarhythm.query.exit.ExitResponder;
 import com.lockarhythm.query.markasdone.MarkAsDoneResponder;
 import com.lockarhythm.query.todo.TodoResponder;
+import com.lockarhythm.query.delete.DeleteResponder;
 import com.lockarhythm.tasks.TaskList;
 
 /** SimpleQueryInterpreter finds the first QueryInterpreter that responds a non-null result. */
@@ -20,6 +21,7 @@ public SimpleQueryInterpreter(TaskList list) {
       new ListResponder(list),
       new DeadlineResponder(list),
       new EventResponder(list),
+      new DeleteResponder(list),
     };
     interpreters = res;
   }
diff --git a/src/main/java/com/lockarhythm/query/delete/DeleteResponder.java b/src/main/java/com/lockarhythm/query/delete/DeleteResponder.java
new file mode 100644
index 00000000..835e04fc
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/delete/DeleteResponder.java
@@ -0,0 +1,29 @@
+package com.lockarhythm.query.delete;
+
+import com.lockarhythm.query.RegexQueryInterpreter;
+import com.lockarhythm.query.Result;
+import com.lockarhythm.query.DeletedTaskResult;
+import com.lockarhythm.tasks.Task;
+import com.lockarhythm.tasks.TaskList;
+
+public class DeleteResponder extends RegexQueryInterpreter {
+  private TaskList list;
+
+  public DeleteResponder(TaskList list) {
+    this.list = list;
+  }
+
+  protected String commandRegex() {
+    return "^delete (\\d+)";
+  }
+
+  public Result onMatch(String[] groups) {
+    int index = Integer.parseInt(groups[1]);
+    try {
+      Task task = list.deleteTask(index - 1);
+      return new DeletedTaskResult(task, list.size());
+    } catch (IndexOutOfBoundsException e) {
+      return new Result(String.format("Item %d is not on the list. I cannot delete it!", index));
+    }
+  }
+}
diff --git a/src/main/java/com/lockarhythm/tasks/TaskList.java b/src/main/java/com/lockarhythm/tasks/TaskList.java
index 6b13544f..19b46e5e 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskList.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskList.java
@@ -37,6 +37,10 @@ public Task markAsDone(int index) {
     return t;
   }
 
+  public Task deleteTask(int index) {
+    return list.remove(index);
+  }
+
   @Override
   public String toString() {
     StringBuilder s = new StringBuilder();
diff --git a/text-ui-test/EXPECTED.TXT b/text-ui-test/EXPECTED.TXT
index 8411ae79..846162e0 100644
--- a/text-ui-test/EXPECTED.TXT
+++ b/text-ui-test/EXPECTED.TXT
@@ -78,6 +78,18 @@
 
 	____________________________________________________________
 
+	____________________________________________________________
+	Item 0 is not on the list. I cannot delete it!
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Noted. I've removed this task:
+		[D][X] return book (by: 10pm)
+	Now you have 3 tasks in the list.
+
+	____________________________________________________________
+
 	____________________________________________________________
 	Bye. Hope to see you again soon!
 
diff --git a/text-ui-test/input.txt b/text-ui-test/input.txt
index 23404b0a..a497bac8 100644
--- a/text-ui-test/input.txt
+++ b/text-ui-test/input.txt
@@ -8,4 +8,6 @@ done 2
 todo done 1
 list
 a-command-that-duke-doesnt-know
+delete 0
+delete 2
 bye

From 38456e3fcec14dbac753f6c8ab8aef5bf9617065 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Sun, 17 Oct 2021 21:53:24 +0800
Subject: [PATCH 23/32] Save tasks (#9)

* WIP. Add Storage.

* Working state.

* And fixed test.

* Basic implementation and cleanup.
---
 BUILD                                         |  9 ++-
 WORKSPACE                                     |  3 +-
 .../lockarhythm/application/Application.java  |  7 ++-
 .../lockarhythm/application/TerminalDuke.java | 11 +++-
 .../java/com/lockarhythm/storage/Storage.java | 59 +++++++++++++++++++
 .../com/lockarhythm/tasks/DeadlineTask.java   |  1 +
 .../java/com/lockarhythm/tasks/EventTask.java |  1 +
 src/main/java/com/lockarhythm/tasks/Task.java |  4 +-
 .../lockarhythm/tasks/TaskDeserializer.java   | 37 ++++++++++++
 .../java/com/lockarhythm/tasks/TaskList.java  |  6 +-
 .../java/com/lockarhythm/tasks/TodoTask.java  |  2 +
 11 files changed, 134 insertions(+), 6 deletions(-)
 create mode 100644 src/main/java/com/lockarhythm/storage/Storage.java
 create mode 100644 src/main/java/com/lockarhythm/tasks/TaskDeserializer.java

diff --git a/BUILD b/BUILD
index ff824a2b..8b8c4a6c 100644
--- a/BUILD
+++ b/BUILD
@@ -5,7 +5,10 @@ java_binary(
     srcs = glob([
         "src/main/java/com/lockarhythm/**/*.java",
     ]),
-    deps = ["@maven//:org_apache_commons_commons_lang3"]
+    deps = [
+        "@maven//:org_apache_commons_commons_lang3",
+        "@maven//:com_google_code_gson_gson",
+        ]
 )
 
 [
@@ -16,6 +19,10 @@ java_binary(
           "src/test/java/com/lockarhythm/**/*.java",
           "src/main/java/com/lockarhythm/**/*.java",
       ]),
+    deps = [
+        "@maven//:org_apache_commons_commons_lang3",
+        "@maven//:com_google_code_gson_gson",
+        ]
   )
   for class_name in [
       "TestTerminalDuke",
diff --git a/WORKSPACE b/WORKSPACE
index 9784f207..960a9371 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -15,7 +15,8 @@ load("@rules_jvm_external//:defs.bzl", "maven_install")
 maven_install(
     artifacts = [
         #"com.google.guava:guava:21.0",
-        "org.apache.commons:commons-lang3:3.11"
+        "org.apache.commons:commons-lang3:3.11",
+        "com.google.code.gson:gson:2.8.8"
     ],
     repositories = [
         # Private repositories are supported through HTTP Basic auth
diff --git a/src/main/java/com/lockarhythm/application/Application.java b/src/main/java/com/lockarhythm/application/Application.java
index ce327aee..bc803d17 100644
--- a/src/main/java/com/lockarhythm/application/Application.java
+++ b/src/main/java/com/lockarhythm/application/Application.java
@@ -3,7 +3,9 @@
 import com.lockarhythm.query.DukeException;
 import com.lockarhythm.query.QueryInterpreter;
 import com.lockarhythm.query.Result;
+import com.lockarhythm.storage.Storage;
 import com.lockarhythm.ui.UI;
+import java.io.IOException;
 
 abstract class Application {
   static String logo =
@@ -13,7 +15,7 @@ abstract class Application {
           + "\t| |_| | |_| |   <  __/\n"
           + "\t|____/ \\__,_|_|\\_\\___|\n";
 
-  public static void run(UI ui, QueryInterpreter q) {
+  public static void run(UI ui, QueryInterpreter q, Storage storage) {
     Result result;
 
     ui.print("Hello I'm\n" + logo, "What can I do for you?");
@@ -21,10 +23,13 @@ public static void run(UI ui, QueryInterpreter q) {
     while (ui.hasNext()) {
       try {
         result = q.interpret(ui.nextLine());
+        storage.overwrite();
         ui.print(result);
         if (result.shouldExit()) {
           break;
         }
+      } catch (IOException e) {
+        ui.print(String.format("Sorry, I cannot save the task to file: %s", e));
       } catch (DukeException e) {
         ui.print("Sorry, I don't understand that yet!");
       }
diff --git a/src/main/java/com/lockarhythm/application/TerminalDuke.java b/src/main/java/com/lockarhythm/application/TerminalDuke.java
index 6cd3823d..693c6209 100644
--- a/src/main/java/com/lockarhythm/application/TerminalDuke.java
+++ b/src/main/java/com/lockarhythm/application/TerminalDuke.java
@@ -2,10 +2,19 @@
 
 import com.lockarhythm.query.SimpleQueryInterpreter;
 import com.lockarhythm.tasks.TaskList;
+import com.lockarhythm.tasks.Task;
 import com.lockarhythm.ui.TerminalUI;
+import com.lockarhythm.storage.Storage;
+import java.util.ArrayList;
+import java.nio.file.Paths;
+import java.nio.file.Path;
 
 final class TerminalDuke extends Application {
   public static void main(String[] args) {
-    run(new TerminalUI(), new SimpleQueryInterpreter(new TaskList()));
+    Path path = Paths.get(".", "tasks.json");
+    Storage storage = new Storage<Task>(path.toString());
+    ArrayList<Task> list = storage.load(Task.class);
+    storage.registerList(list);
+    run(new TerminalUI(), new SimpleQueryInterpreter(new TaskList(list)), storage);
   }
 }
diff --git a/src/main/java/com/lockarhythm/storage/Storage.java b/src/main/java/com/lockarhythm/storage/Storage.java
new file mode 100644
index 00000000..bd5ce962
--- /dev/null
+++ b/src/main/java/com/lockarhythm/storage/Storage.java
@@ -0,0 +1,59 @@
+package com.lockarhythm.storage;
+
+
+import com.google.gson.GsonBuilder;
+import com.google.gson.Gson;
+import com.google.gson.reflect.TypeToken;
+import java.lang.reflect.Type;
+
+import java.io.FileOutputStream;
+import java.io.ObjectOutputStream;
+import java.io.IOException;
+import java.io.Serializable;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.charset.StandardCharsets;
+
+import com.lockarhythm.tasks.TaskDeserializer;
+import com.lockarhythm.tasks.Task;
+
+import java.util.ArrayList;
+
+public class Storage<T> {
+  private String filePath;
+
+  private ArrayList<T> list;
+
+  public Storage(String filePath) {
+    this.filePath = filePath;
+  }
+
+  public void registerList(ArrayList<T> list) {
+    this.list = list;
+  }
+
+  public ArrayList<T> load(Class<T> type) {
+    String content;
+    try {
+      content = Files.readString(Path.of(filePath), StandardCharsets.UTF_8);
+
+      TaskDeserializer deserializer = new TaskDeserializer("_type");
+      Gson gson = new GsonBuilder()
+        .registerTypeAdapter(Task.class, deserializer)
+        .create();
+      Type typeOfT = TypeToken.getParameterized(ArrayList.class, type).getType();
+      return gson.fromJson(content, new TypeToken<ArrayList<Task>>(){}.getType());
+    } catch (IOException e) {
+      return new ArrayList<T>();
+    }
+  }
+
+  public void overwrite() throws IOException {
+    FileOutputStream fo = new FileOutputStream(filePath);
+
+    Gson gson = new GsonBuilder().setPrettyPrinting().create();
+
+    String js = gson.toJson(list);
+    fo.write(js.getBytes());
+  }
+}
diff --git a/src/main/java/com/lockarhythm/tasks/DeadlineTask.java b/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
index 0973e7ef..030d47cd 100644
--- a/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
+++ b/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
@@ -2,6 +2,7 @@
 
 final class DeadlineTask extends Task {
   private String by;
+  private String _type = "DEADLINE";
 
   public DeadlineTask(String description, String by) {
     super(description);
diff --git a/src/main/java/com/lockarhythm/tasks/EventTask.java b/src/main/java/com/lockarhythm/tasks/EventTask.java
index a2910830..9b521d65 100644
--- a/src/main/java/com/lockarhythm/tasks/EventTask.java
+++ b/src/main/java/com/lockarhythm/tasks/EventTask.java
@@ -2,6 +2,7 @@
 
 final class EventTask extends Task {
   private String at;
+  private String _type = "EVENT";
 
   public EventTask(String description, String at) {
     super(description);
diff --git a/src/main/java/com/lockarhythm/tasks/Task.java b/src/main/java/com/lockarhythm/tasks/Task.java
index fb554905..6a114622 100644
--- a/src/main/java/com/lockarhythm/tasks/Task.java
+++ b/src/main/java/com/lockarhythm/tasks/Task.java
@@ -1,6 +1,8 @@
 package com.lockarhythm.tasks;
 
-public abstract class Task {
+import java.io.Serializable;
+
+public abstract class Task implements Serializable {
   private String description;
   private boolean isDone;
 
diff --git a/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java b/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java
new file mode 100644
index 00000000..362edbc1
--- /dev/null
+++ b/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java
@@ -0,0 +1,37 @@
+package com.lockarhythm.tasks;
+
+import com.google.gson.*;
+import java.lang.reflect.Type;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Technique credit to https://www.baeldung.com/gson-list
+ */
+public class TaskDeserializer implements JsonDeserializer<Task> {
+    private String taskTypeElementName;
+    private Gson gson;
+    private Map<String, Class<? extends Task>> taskTypeRegistry;
+
+    public TaskDeserializer(String taskTypeElementName) {
+        this.taskTypeElementName = taskTypeElementName;
+        this.gson = new Gson();
+        this.taskTypeRegistry = new HashMap<>();
+
+        this.registerTaskType("DEADLINE", DeadlineTask.class);
+        this.registerTaskType("TODO", TodoTask.class);
+        this.registerTaskType("EVENT", EventTask.class);
+    }
+
+    public void registerTaskType(String taskTypeName, Class<? extends Task> taskType) {
+        taskTypeRegistry.put(taskTypeName, taskType);
+    }
+
+    public Task deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) {
+        JsonObject taskObject = json.getAsJsonObject();
+        JsonElement taskTypeElement = taskObject.get(taskTypeElementName);
+
+        Class<? extends Task> taskType = taskTypeRegistry.get(taskTypeElement.getAsString());
+        return gson.fromJson(taskObject, taskType);
+    }
+}
diff --git a/src/main/java/com/lockarhythm/tasks/TaskList.java b/src/main/java/com/lockarhythm/tasks/TaskList.java
index 19b46e5e..781a85c5 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskList.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskList.java
@@ -6,7 +6,11 @@ public class TaskList {
   private ArrayList<Task> list;
 
   public TaskList() {
-    list = new ArrayList<Task>();
+    this.list = new ArrayList<Task>();
+  }
+
+  public TaskList(ArrayList<Task> list) {
+    this.list = list;
   }
 
   public int size() {
diff --git a/src/main/java/com/lockarhythm/tasks/TodoTask.java b/src/main/java/com/lockarhythm/tasks/TodoTask.java
index 38b1e9cc..f7e2c263 100644
--- a/src/main/java/com/lockarhythm/tasks/TodoTask.java
+++ b/src/main/java/com/lockarhythm/tasks/TodoTask.java
@@ -1,6 +1,8 @@
 package com.lockarhythm.tasks;
 
 public final class TodoTask extends Task {
+  private String _type = "TODO";
+
   public TodoTask(String description) {
     super(description);
   }

From 59884c4352631f3995e17835991f63edce54c2e8 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Mon, 18 Oct 2021 00:10:18 +0800
Subject: [PATCH 24/32] Implement Level-8 minimum. (#10)

* Implement Level-8 minimum.

* Fix and add more tests. And basic date time parsing.

* Store datetime.
---
 .../query/deadline/DeadlineResponder.java     | 11 ++++++--
 .../query/event/EventResponder.java           |  8 ++++--
 .../com/lockarhythm/tasks/DeadlineTask.java   |  4 +--
 .../java/com/lockarhythm/tasks/EventTask.java |  4 +--
 .../java/com/lockarhythm/tasks/TaskDate.java  | 18 ++++++++++++
 text-ui-test/EXPECTED.TXT                     | 28 +++++++++++++------
 text-ui-test/input.txt                        |  2 ++
 text-ui-test/runtest.sh                       | 10 +++++++
 8 files changed, 67 insertions(+), 18 deletions(-)
 create mode 100644 src/main/java/com/lockarhythm/tasks/TaskDate.java

diff --git a/src/main/java/com/lockarhythm/query/deadline/DeadlineResponder.java b/src/main/java/com/lockarhythm/query/deadline/DeadlineResponder.java
index 3bfabe5a..8e6cc1bd 100644
--- a/src/main/java/com/lockarhythm/query/deadline/DeadlineResponder.java
+++ b/src/main/java/com/lockarhythm/query/deadline/DeadlineResponder.java
@@ -1,8 +1,8 @@
 package com.lockarhythm.query.deadline;
 
+import com.lockarhythm.query.AddedTaskResult;
 import com.lockarhythm.query.RegexQueryInterpreter;
 import com.lockarhythm.query.Result;
-import com.lockarhythm.query.AddedTaskResult;
 import com.lockarhythm.tasks.Task;
 import com.lockarhythm.tasks.TaskList;
 
@@ -18,7 +18,12 @@ protected String commandRegex() {
   }
 
   public Result onMatch(String[] groups) {
-    Task task = list.addDeadlineTask(groups[1], groups[2]);
-    return new AddedTaskResult(task, list.size());
+    try {
+      Task task = list.addDeadlineTask(groups[1], groups[2]);
+      return new AddedTaskResult(task, list.size());
+    } catch (java.time.format.DateTimeParseException e) {
+      return new Result(
+          String.format("Please give me a valid LocalDate pattern: %s", e.getMessage()));
+    }
   }
 }
diff --git a/src/main/java/com/lockarhythm/query/event/EventResponder.java b/src/main/java/com/lockarhythm/query/event/EventResponder.java
index d69a73bf..6db6f085 100644
--- a/src/main/java/com/lockarhythm/query/event/EventResponder.java
+++ b/src/main/java/com/lockarhythm/query/event/EventResponder.java
@@ -18,7 +18,11 @@ protected String commandRegex() {
   }
 
   public Result onMatch(String[] groups) {
-    Task task = list.addEventTask(groups[1], groups[2]);
-    return new AddedTaskResult(task, list.size());
+    try {
+      Task task = list.addEventTask(groups[1], groups[2]);
+      return new AddedTaskResult(task, list.size());
+    } catch(java.time.format.DateTimeParseException e) {
+      return new Result(String.format("Please give me a valid LocalDate pattern: %s", e.getMessage()));
+    }
   }
 }
diff --git a/src/main/java/com/lockarhythm/tasks/DeadlineTask.java b/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
index 030d47cd..d5a1eaa9 100644
--- a/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
+++ b/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
@@ -1,12 +1,12 @@
 package com.lockarhythm.tasks;
 
 final class DeadlineTask extends Task {
-  private String by;
+  private TaskDate by;
   private String _type = "DEADLINE";
 
   public DeadlineTask(String description, String by) {
     super(description);
-    this.by = by;
+    this.by = new TaskDate(by);
   }
 
   @Override
diff --git a/src/main/java/com/lockarhythm/tasks/EventTask.java b/src/main/java/com/lockarhythm/tasks/EventTask.java
index 9b521d65..67fcc45f 100644
--- a/src/main/java/com/lockarhythm/tasks/EventTask.java
+++ b/src/main/java/com/lockarhythm/tasks/EventTask.java
@@ -1,12 +1,12 @@
 package com.lockarhythm.tasks;
 
 final class EventTask extends Task {
-  private String at;
+  private TaskDate at;
   private String _type = "EVENT";
 
   public EventTask(String description, String at) {
     super(description);
-    this.at = at;
+    this.at = new TaskDate(at);
   }
 
   @Override
diff --git a/src/main/java/com/lockarhythm/tasks/TaskDate.java b/src/main/java/com/lockarhythm/tasks/TaskDate.java
new file mode 100644
index 00000000..1c68a5e3
--- /dev/null
+++ b/src/main/java/com/lockarhythm/tasks/TaskDate.java
@@ -0,0 +1,18 @@
+package com.lockarhythm.tasks;
+
+import java.io.Serializable;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+
+class TaskDate implements Serializable {
+  private LocalDateTime d;
+
+  public TaskDate(String s) {
+    d = LocalDateTime.parse(s);
+  }
+
+  @Override
+  public String toString() {
+    return d.format(DateTimeFormatter.ofPattern("MMM d yyyy"));
+  }
+}
diff --git a/text-ui-test/EXPECTED.TXT b/text-ui-test/EXPECTED.TXT
index 846162e0..d499a6f7 100644
--- a/text-ui-test/EXPECTED.TXT
+++ b/text-ui-test/EXPECTED.TXT
@@ -17,16 +17,26 @@
 
 	____________________________________________________________
 
+	____________________________________________________________
+	Please give me a valid LocalDate pattern: Text '10pm' could not be parsed at index 0
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Please give me a valid LocalDate pattern: Text 'Sunday 11pm' could not be parsed at index 0
+
+	____________________________________________________________
+
 	____________________________________________________________
 	Got it. I've added this task:
-		[D][ ] return book (by: 10pm)
+		[D][ ] return book (by: Dec 31 2021)
 	Now you have 2 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Got it. I've added this task:
-		[E][ ] buy bread (at: Sunday 11pm)
+		[E][ ] buy bread (at: Nov 30 2021)
 	Now you have 3 tasks in the list.
 
 	____________________________________________________________
@@ -40,20 +50,20 @@
 	____________________________________________________________
 	Here are the tasks in your list:
 	1.[T][X] borrow book
-	2.[D][ ] return book (by: 10pm)
-	3.[E][ ] buy bread (at: Sunday 11pm)
+	2.[D][ ] return book (by: Dec 31 2021)
+	3.[E][ ] buy bread (at: Nov 30 2021)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Nice! I've marked this task as done:
-		[D][X] return book (by: 10pm)
+		[D][X] return book (by: Dec 31 2021)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Nice! I've marked this task as done:
-		[D][X] return book (by: 10pm)
+		[D][X] return book (by: Dec 31 2021)
 
 	____________________________________________________________
 
@@ -67,8 +77,8 @@
 	____________________________________________________________
 	Here are the tasks in your list:
 	1.[T][X] borrow book
-	2.[D][X] return book (by: 10pm)
-	3.[E][ ] buy bread (at: Sunday 11pm)
+	2.[D][X] return book (by: Dec 31 2021)
+	3.[E][ ] buy bread (at: Nov 30 2021)
 	4.[T][ ] done 1
 
 	____________________________________________________________
@@ -85,7 +95,7 @@
 
 	____________________________________________________________
 	Noted. I've removed this task:
-		[D][X] return book (by: 10pm)
+		[D][X] return book (by: Dec 31 2021)
 	Now you have 3 tasks in the list.
 
 	____________________________________________________________
diff --git a/text-ui-test/input.txt b/text-ui-test/input.txt
index a497bac8..6075af08 100644
--- a/text-ui-test/input.txt
+++ b/text-ui-test/input.txt
@@ -1,6 +1,8 @@
 todo borrow book
 deadline return book /by 10pm
 event buy bread /at Sunday 11pm
+deadline return book /by 2021-12-31T23:59:59
+event buy bread /at 2021-11-30T23:59:59
 done 1
 list
 done 2
diff --git a/text-ui-test/runtest.sh b/text-ui-test/runtest.sh
index c69a991f..5504e370 100755
--- a/text-ui-test/runtest.sh
+++ b/text-ui-test/runtest.sh
@@ -12,9 +12,16 @@ then
     rm ACTUAL.TXT
 fi
 
+# delete tasks.json from previous run
+if [ -e "./tasks.json" ]
+then
+    rm tasks.json
+fi
+
 # compile the code into the bin folder, terminates if error occurred
 if ! bazel build //:TerminalDuke 
 then
+    rm tasks.json
     echo "********** BUILD FAILURE **********"
     exit 1
 fi
@@ -26,6 +33,9 @@ fi
 cp EXPECTED.TXT EXPECTED-UNIX.TXT
 dos2unix ACTUAL.TXT EXPECTED-UNIX.TXT
 
+# Clean up
+rm tasks.json
+
 # compare the output to the expected output
 diff ACTUAL.TXT EXPECTED-UNIX.TXT
 if [ $? -eq 0 ]

From a8eccff79a2805adc7f5e9a680509f082cfcbde6 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Mon, 18 Oct 2021 00:55:15 +0800
Subject: [PATCH 25/32] Improve Text UI tests. Added tests for saved serialized
 data. (#11)

* Improve ui tests. Added serialization tests.

* Fix workflow.

* Remove tasks.json
---
 .github/workflows/workflow.yml |  6 ++++++
 .gitignore                     |  1 +
 text-ui-test/EXPECTED.json     | 32 ++++++++++++++++++++++++++++++++
 text-ui-test/runtest.sh        | 18 ++++++++++++------
 4 files changed, 51 insertions(+), 6 deletions(-)
 create mode 100644 text-ui-test/EXPECTED.json

diff --git a/.github/workflows/workflow.yml b/.github/workflows/workflow.yml
index 25cc361b..57f68586 100644
--- a/.github/workflows/workflow.yml
+++ b/.github/workflows/workflow.yml
@@ -24,6 +24,12 @@ jobs:
       run: |
         "${GITHUB_WORKSPACE}/bin/bazel" test //...
 
+    - name: Run UI and Serialization Tests
+      working-directory: ./text-ui-test
+      run: |
+        chmod +x runtest.sh
+        ./runtest.sh
+
     - name: Build JAR File
       run: |
         "${GITHUB_WORKSPACE}/bin/bazel" build //:TerminalDuke_deploy.jar
diff --git a/.gitignore b/.gitignore
index b957cd08..d08823f6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,6 +14,7 @@ src/main/resources/docs/
 bin/
 
 /text-ui-test/ACTUAL.txt
+/text-ui-test/tasks.json
 text-ui-test/EXPECTED-UNIX.TXT
 
 # Ignore all bazel-* symlinks. There is no full list since this can change
diff --git a/text-ui-test/EXPECTED.json b/text-ui-test/EXPECTED.json
new file mode 100644
index 00000000..7bde0bb7
--- /dev/null
+++ b/text-ui-test/EXPECTED.json
@@ -0,0 +1,32 @@
+[
+  {
+    "_type": "TODO",
+    "description": "borrow book",
+    "isDone": true
+  },
+  {
+    "at": {
+      "d": {
+        "date": {
+          "year": 2021,
+          "month": 11,
+          "day": 30
+        },
+        "time": {
+          "hour": 23,
+          "minute": 59,
+          "second": 59,
+          "nano": 0
+        }
+      }
+    },
+    "_type": "EVENT",
+    "description": "buy bread",
+    "isDone": false
+  },
+  {
+    "_type": "TODO",
+    "description": "done 1",
+    "isDone": false
+  }
+]
\ No newline at end of file
diff --git a/text-ui-test/runtest.sh b/text-ui-test/runtest.sh
index 5504e370..450fb1c3 100755
--- a/text-ui-test/runtest.sh
+++ b/text-ui-test/runtest.sh
@@ -21,7 +21,6 @@ fi
 # compile the code into the bin folder, terminates if error occurred
 if ! bazel build //:TerminalDuke 
 then
-    rm tasks.json
     echo "********** BUILD FAILURE **********"
     exit 1
 fi
@@ -33,16 +32,23 @@ fi
 cp EXPECTED.TXT EXPECTED-UNIX.TXT
 dos2unix ACTUAL.TXT EXPECTED-UNIX.TXT
 
-# Clean up
-rm tasks.json
-
 # compare the output to the expected output
 diff ACTUAL.TXT EXPECTED-UNIX.TXT
 if [ $? -eq 0 ]
 then
-    echo "Test result: PASSED"
+    echo "Test result: PASSED [UI TESTS]"
+else
+    echo "Test result: FAILED [UI TESTS]"
+    exit 1
+fi
+
+# compare the output to the expected output
+diff tasks.json EXPECTED.json
+if [ $? -eq 0 ]
+then
+    echo "Test result: PASSED [SERIALIZATION TESTS]"
     exit 0
 else
-    echo "Test result: FAILED"
+    echo "Test result: FAILED [SERIALIZATION TESTS]"
     exit 1
 fi

From 0c8a48eee4e70667a9a7d9437a07c64885ab9123 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Sun, 24 Oct 2021 23:59:53 +0800
Subject: [PATCH 26/32] Implement C-Sort: Sort tasks by "Date" or" Done" fields
 (#12)

* Add sorting by date or done field, with ui tests.
* Use own Gson date serializers
* Use a fixed bazelisk version for more deterministic builds.
* Update README.md
---
 README.md                                     |  7 +-
 .../query/SimpleQueryInterpreter.java         |  2 +
 .../lockarhythm/query/sort/SortResponder.java | 56 ++++++++++++
 .../lockarhythm/storage/GsonLocalDate.java    | 21 +++++
 .../storage/GsonLocalDateTime.java            | 21 +++++
 .../java/com/lockarhythm/storage/Storage.java | 24 +++--
 .../com/lockarhythm/tasks/DeadlineTask.java   |  5 ++
 .../java/com/lockarhythm/tasks/EventTask.java |  5 ++
 src/main/java/com/lockarhythm/tasks/Task.java |  7 ++
 .../java/com/lockarhythm/tasks/TaskDate.java  |  4 +
 .../lockarhythm/tasks/TaskDeserializer.java   | 12 ++-
 .../java/com/lockarhythm/tasks/TaskList.java  | 30 +++++++
 text-ui-test/EXPECTED.TXT                     | 90 +++++++++++++++++++
 text-ui-test/EXPECTED.json                    | 30 ++++---
 text-ui-test/input.txt                        | 10 +++
 text-ui-test/runtest.sh                       |  2 +-
 16 files changed, 301 insertions(+), 25 deletions(-)
 create mode 100644 src/main/java/com/lockarhythm/query/sort/SortResponder.java
 create mode 100644 src/main/java/com/lockarhythm/storage/GsonLocalDate.java
 create mode 100644 src/main/java/com/lockarhythm/storage/GsonLocalDateTime.java

diff --git a/README.md b/README.md
index e260776c..a54cf64b 100644
--- a/README.md
+++ b/README.md
@@ -14,10 +14,13 @@ Prerequisites: Have `bazel` installed.
 To build for local development on macOS:
 ```bash
 # bazel makes a wrapper script around the jar file.
-bazel build //:Duke && ./bazel-bin/Duke
+bazel build //:TerminalDuke && ./bazel-bin/TerminalDuke
 
 # or simply
-bazel run //:Duke
+bazel run //:TerminalDuke
+
+# Use bazelisk for M1 Macs (Apple Silicon)
+USE_BAZEL_VERSION=ac9353fab161efae4af72e73fbb657a762b3620d bazelisk run //:TerminalDuke
 ```
 
 To build jar file for deployment purposes:
diff --git a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
index 64d03e4f..417edf61 100644
--- a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
+++ b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
@@ -7,6 +7,7 @@
 import com.lockarhythm.query.markasdone.MarkAsDoneResponder;
 import com.lockarhythm.query.todo.TodoResponder;
 import com.lockarhythm.query.delete.DeleteResponder;
+import com.lockarhythm.query.sort.SortResponder;
 import com.lockarhythm.tasks.TaskList;
 
 /** SimpleQueryInterpreter finds the first QueryInterpreter that responds a non-null result. */
@@ -22,6 +23,7 @@ public SimpleQueryInterpreter(TaskList list) {
       new DeadlineResponder(list),
       new EventResponder(list),
       new DeleteResponder(list),
+      new SortResponder(list),
     };
     interpreters = res;
   }
diff --git a/src/main/java/com/lockarhythm/query/sort/SortResponder.java b/src/main/java/com/lockarhythm/query/sort/SortResponder.java
new file mode 100644
index 00000000..71ae7a9b
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/sort/SortResponder.java
@@ -0,0 +1,56 @@
+package com.lockarhythm.query.sort;
+
+import com.lockarhythm.query.RegexQueryInterpreter;
+import com.lockarhythm.query.Result;
+import com.lockarhythm.tasks.TaskList;
+
+public class SortResponder extends RegexQueryInterpreter {
+  private final static boolean DEFAULT_SORT_ORDER = true;
+
+  private TaskList list;
+
+  public SortResponder(TaskList list) {
+    this.list = list;
+  }
+
+  protected String commandRegex() {
+    return "^sort by (date|done)( desc| asc)?$";
+  }
+
+  public Result onMatch(String[] groups) {
+    String sortKey = groups[1];
+    boolean isAscending = parseIsAscending(groups[2]);
+
+    TaskList sortedList = sortBy(sortKey, isAscending);
+
+    return new Result(String.format("Ok! I have sorted the tasks by %s in %s order!\n%s", sortKey, isAscending ? "ascending" : "descending", sortedList));
+  }
+
+  private boolean parseIsAscending(String value) {
+    if (value == null) {
+      return DEFAULT_SORT_ORDER;
+    }
+    String s = value.trim();
+    if (s.equals("desc")) {
+      return false;
+    } else if (s.equals("asc")) {
+      return true;
+    } else {
+      return DEFAULT_SORT_ORDER;
+    }
+  }
+
+  /**
+   * Sorts by the `sortKey` in the order given by `isAscending`.
+   */
+  private TaskList sortBy(String sortKey, boolean isAscending) {
+    switch(sortKey) {
+      case "done":
+        return list.sortByDone(isAscending);
+      case "date":
+        return list.sortByTaskDate(isAscending);
+      default:
+    };
+    return list.sortByTaskDate(isAscending);
+  }
+}
diff --git a/src/main/java/com/lockarhythm/storage/GsonLocalDate.java b/src/main/java/com/lockarhythm/storage/GsonLocalDate.java
new file mode 100644
index 00000000..7eb94a47
--- /dev/null
+++ b/src/main/java/com/lockarhythm/storage/GsonLocalDate.java
@@ -0,0 +1,21 @@
+package com.lockarhythm.storage;
+
+import com.google.gson.*;
+
+import java.lang.reflect.Type;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+
+public class GsonLocalDate implements JsonSerializer<LocalDate>, JsonDeserializer<LocalDate> {
+
+    @Override
+    public LocalDate deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
+        String ldtString = jsonElement.getAsString();
+        return LocalDate.parse(ldtString,DateTimeFormatter.ISO_LOCAL_DATE);
+    }
+
+    @Override
+    public JsonElement serialize(LocalDate localDate, Type type, JsonSerializationContext jsonSerializationContext) {
+        return new JsonPrimitive(localDate.format(DateTimeFormatter.ISO_LOCAL_DATE));
+    }
+}
diff --git a/src/main/java/com/lockarhythm/storage/GsonLocalDateTime.java b/src/main/java/com/lockarhythm/storage/GsonLocalDateTime.java
new file mode 100644
index 00000000..95878f75
--- /dev/null
+++ b/src/main/java/com/lockarhythm/storage/GsonLocalDateTime.java
@@ -0,0 +1,21 @@
+package com.lockarhythm.storage;
+
+import com.google.gson.*;
+
+import java.lang.reflect.Type;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+
+public class GsonLocalDateTime implements JsonSerializer<LocalDateTime>, JsonDeserializer<LocalDateTime> {
+
+    @Override
+    public LocalDateTime deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
+        String ldtString = jsonElement.getAsString();
+        return LocalDateTime.parse(ldtString,DateTimeFormatter.ISO_LOCAL_DATE_TIME);
+    }
+
+    @Override
+    public JsonElement serialize(LocalDateTime localDateTime, Type type, JsonSerializationContext jsonSerializationContext) {
+        return new JsonPrimitive(localDateTime.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME));
+    }
+}
diff --git a/src/main/java/com/lockarhythm/storage/Storage.java b/src/main/java/com/lockarhythm/storage/Storage.java
index bd5ce962..052d2e04 100644
--- a/src/main/java/com/lockarhythm/storage/Storage.java
+++ b/src/main/java/com/lockarhythm/storage/Storage.java
@@ -5,6 +5,8 @@
 import com.google.gson.Gson;
 import com.google.gson.reflect.TypeToken;
 import java.lang.reflect.Type;
+import java.time.LocalDateTime;
+import java.time.LocalDate;
 
 import java.io.FileOutputStream;
 import java.io.ObjectOutputStream;
@@ -24,8 +26,17 @@ public class Storage<T> {
 
   private ArrayList<T> list;
 
+  private Gson gson;
+
   public Storage(String filePath) {
     this.filePath = filePath;
+
+    gson = new GsonBuilder()
+      .registerTypeAdapter(Task.class, new TaskDeserializer("_type"))
+      .registerTypeAdapter(LocalDateTime.class, new GsonLocalDateTime())
+      .registerTypeAdapter(LocalDate.class, new GsonLocalDate())
+      .setPrettyPrinting()
+      .create();
   }
 
   public void registerList(ArrayList<T> list) {
@@ -37,12 +48,12 @@ public ArrayList<T> load(Class<T> type) {
     try {
       content = Files.readString(Path.of(filePath), StandardCharsets.UTF_8);
 
-      TaskDeserializer deserializer = new TaskDeserializer("_type");
-      Gson gson = new GsonBuilder()
-        .registerTypeAdapter(Task.class, deserializer)
-        .create();
       Type typeOfT = TypeToken.getParameterized(ArrayList.class, type).getType();
-      return gson.fromJson(content, new TypeToken<ArrayList<Task>>(){}.getType());
+      ArrayList<T> deserialized = gson.fromJson(content, new TypeToken<ArrayList<Task>>(){}.getType());
+      if (deserialized == null) {
+        return new ArrayList<T>();
+      }
+      return deserialized;
     } catch (IOException e) {
       return new ArrayList<T>();
     }
@@ -50,9 +61,6 @@ public ArrayList<T> load(Class<T> type) {
 
   public void overwrite() throws IOException {
     FileOutputStream fo = new FileOutputStream(filePath);
-
-    Gson gson = new GsonBuilder().setPrettyPrinting().create();
-
     String js = gson.toJson(list);
     fo.write(js.getBytes());
   }
diff --git a/src/main/java/com/lockarhythm/tasks/DeadlineTask.java b/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
index d5a1eaa9..d6239988 100644
--- a/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
+++ b/src/main/java/com/lockarhythm/tasks/DeadlineTask.java
@@ -9,6 +9,11 @@ public DeadlineTask(String description, String by) {
     this.by = new TaskDate(by);
   }
 
+  @Override
+  public TaskDate getTaskDate() {
+    return by;
+  }
+
   @Override
   protected String getTaskTypeIcon() {
     return "D";
diff --git a/src/main/java/com/lockarhythm/tasks/EventTask.java b/src/main/java/com/lockarhythm/tasks/EventTask.java
index 67fcc45f..60b8c5b2 100644
--- a/src/main/java/com/lockarhythm/tasks/EventTask.java
+++ b/src/main/java/com/lockarhythm/tasks/EventTask.java
@@ -9,6 +9,11 @@ public EventTask(String description, String at) {
     this.at = new TaskDate(at);
   }
 
+  @Override
+  public TaskDate getTaskDate() {
+    return at;
+  }
+
   @Override
   protected String getTaskTypeIcon() {
     return "E";
diff --git a/src/main/java/com/lockarhythm/tasks/Task.java b/src/main/java/com/lockarhythm/tasks/Task.java
index 6a114622..e140b65f 100644
--- a/src/main/java/com/lockarhythm/tasks/Task.java
+++ b/src/main/java/com/lockarhythm/tasks/Task.java
@@ -3,6 +3,9 @@
 import java.io.Serializable;
 
 public abstract class Task implements Serializable {
+  private transient static String DEFAULT_TASK_DATE_VALUE = "3000-12-31T23:59:59";
+  private transient static TaskDate DEFAULT_TASK_DATE = new TaskDate(DEFAULT_TASK_DATE_VALUE);
+
   private String description;
   private boolean isDone;
 
@@ -27,6 +30,10 @@ public boolean isDone() {
     return isDone;
   }
 
+  public TaskDate getTaskDate() {
+    return DEFAULT_TASK_DATE;
+  }
+
   private String getDoneIcon() {
     return isDone ? "X" : " ";
   }
diff --git a/src/main/java/com/lockarhythm/tasks/TaskDate.java b/src/main/java/com/lockarhythm/tasks/TaskDate.java
index 1c68a5e3..2dd89b18 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskDate.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskDate.java
@@ -11,6 +11,10 @@ public TaskDate(String s) {
     d = LocalDateTime.parse(s);
   }
 
+  public static int compare(TaskDate x, TaskDate y) {
+    return x.d.compareTo(y.d);
+  }
+
   @Override
   public String toString() {
     return d.format(DateTimeFormatter.ofPattern("MMM d yyyy"));
diff --git a/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java b/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java
index 362edbc1..a00f4b0b 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java
@@ -5,6 +5,12 @@
 import java.util.HashMap;
 import java.util.Map;
 
+import com.lockarhythm.storage.GsonLocalDateTime;
+import com.lockarhythm.storage.GsonLocalDate;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+
 /**
  * Technique credit to https://www.baeldung.com/gson-list
  */
@@ -14,8 +20,12 @@ public class TaskDeserializer implements JsonDeserializer<Task> {
     private Map<String, Class<? extends Task>> taskTypeRegistry;
 
     public TaskDeserializer(String taskTypeElementName) {
+        this.gson = new GsonBuilder()
+          .registerTypeAdapter(LocalDateTime.class, new GsonLocalDateTime())
+          .registerTypeAdapter(LocalDate.class, new GsonLocalDate())
+          .create();
+
         this.taskTypeElementName = taskTypeElementName;
-        this.gson = new Gson();
         this.taskTypeRegistry = new HashMap<>();
 
         this.registerTaskType("DEADLINE", DeadlineTask.class);
diff --git a/src/main/java/com/lockarhythm/tasks/TaskList.java b/src/main/java/com/lockarhythm/tasks/TaskList.java
index 781a85c5..299a7dd0 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskList.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskList.java
@@ -1,6 +1,8 @@
 package com.lockarhythm.tasks;
 
 import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.Collections;
 
 public class TaskList {
   private ArrayList<Task> list;
@@ -45,6 +47,34 @@ public Task deleteTask(int index) {
     return list.remove(index);
   }
 
+  /**
+   * Returns a copy of TaskList sorted by the task date.
+   */
+  public TaskList sortByTaskDate(boolean isAscending) {
+    ArrayList<Task> copy = new ArrayList<Task>(list);
+    Collections.sort(copy, (a, b) -> {
+      if (isAscending) {
+        return TaskDate.compare(a.getTaskDate(), b.getTaskDate());
+      }
+      return TaskDate.compare(b.getTaskDate(), a.getTaskDate());
+    });
+    return new TaskList(copy);
+  }
+
+  /**
+   * Returns a copy of TaskList sorted by the "done" field.
+   */
+  public TaskList sortByDone(boolean isAscending) {
+    ArrayList<Task> copy = new ArrayList<Task>(list);
+    Collections.sort(copy, (a, b) -> {
+      if (isAscending) {
+        return Boolean.compare(b.isDone(), a.isDone());
+      }
+      return Boolean.compare(a.isDone(), b.isDone());
+    });
+    return new TaskList(copy);
+  }
+
   @Override
   public String toString() {
     StringBuilder s = new StringBuilder();
diff --git a/text-ui-test/EXPECTED.TXT b/text-ui-test/EXPECTED.TXT
index d499a6f7..1f1854db 100644
--- a/text-ui-test/EXPECTED.TXT
+++ b/text-ui-test/EXPECTED.TXT
@@ -100,6 +100,96 @@
 
 	____________________________________________________________
 
+	____________________________________________________________
+	Got it. I've added this task:
+		[E][ ] this task is so 2008 (at: Oct 31 2008)
+	Now you have 4 tasks in the list.
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Got it. I've added this task:
+		[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+	Now you have 5 tasks in the list.
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Ok! I have sorted the tasks by date in ascending order!
+	1.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+	2.[E][ ] this task is so 2008 (at: Oct 31 2008)
+	3.[E][ ] buy bread (at: Nov 30 2021)
+	4.[T][X] borrow book
+	5.[T][ ] done 1
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Ok! I have sorted the tasks by date in descending order!
+	1.[T][X] borrow book
+	2.[T][ ] done 1
+	3.[E][ ] buy bread (at: Nov 30 2021)
+	4.[E][ ] this task is so 2008 (at: Oct 31 2008)
+	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Here are the tasks in your list:
+	1.[T][X] borrow book
+	2.[E][ ] buy bread (at: Nov 30 2021)
+	3.[T][ ] done 1
+	4.[E][ ] this task is so 2008 (at: Oct 31 2008)
+	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Nice! I've marked this task as done:
+		[T][X] done 1
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Ok! I have sorted the tasks by done in ascending order!
+	1.[T][X] borrow book
+	2.[T][X] done 1
+	3.[E][ ] buy bread (at: Nov 30 2021)
+	4.[E][ ] this task is so 2008 (at: Oct 31 2008)
+	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Ok! I have sorted the tasks by done in ascending order!
+	1.[T][X] borrow book
+	2.[T][X] done 1
+	3.[E][ ] buy bread (at: Nov 30 2021)
+	4.[E][ ] this task is so 2008 (at: Oct 31 2008)
+	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Ok! I have sorted the tasks by done in descending order!
+	1.[E][ ] buy bread (at: Nov 30 2021)
+	2.[E][ ] this task is so 2008 (at: Oct 31 2008)
+	3.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+	4.[T][X] borrow book
+	5.[T][X] done 1
+
+	____________________________________________________________
+
+	____________________________________________________________
+	Here are the tasks in your list:
+	1.[T][X] borrow book
+	2.[E][ ] buy bread (at: Nov 30 2021)
+	3.[T][X] done 1
+	4.[E][ ] this task is so 2008 (at: Oct 31 2008)
+	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+
+	____________________________________________________________
+
 	____________________________________________________________
 	Bye. Hope to see you again soon!
 
diff --git a/text-ui-test/EXPECTED.json b/text-ui-test/EXPECTED.json
index 7bde0bb7..19d2198c 100644
--- a/text-ui-test/EXPECTED.json
+++ b/text-ui-test/EXPECTED.json
@@ -6,19 +6,7 @@
   },
   {
     "at": {
-      "d": {
-        "date": {
-          "year": 2021,
-          "month": 11,
-          "day": 30
-        },
-        "time": {
-          "hour": 23,
-          "minute": 59,
-          "second": 59,
-          "nano": 0
-        }
-      }
+      "d": "2021-11-30T23:59:59"
     },
     "_type": "EVENT",
     "description": "buy bread",
@@ -27,6 +15,22 @@
   {
     "_type": "TODO",
     "description": "done 1",
+    "isDone": true
+  },
+  {
+    "at": {
+      "d": "2008-10-31T23:59:59"
+    },
+    "_type": "EVENT",
+    "description": "this task is so 2008",
+    "isDone": false
+  },
+  {
+    "at": {
+      "d": "2000-12-31T23:59:59"
+    },
+    "_type": "EVENT",
+    "description": "this task is so 2000-and-late",
     "isDone": false
   }
 ]
\ No newline at end of file
diff --git a/text-ui-test/input.txt b/text-ui-test/input.txt
index 6075af08..0369d4ae 100644
--- a/text-ui-test/input.txt
+++ b/text-ui-test/input.txt
@@ -12,4 +12,14 @@ list
 a-command-that-duke-doesnt-know
 delete 0
 delete 2
+event this task is so 2008 /at 2008-10-31T23:59:59
+event this task is so 2000-and-late /at 2000-12-31T23:59:59
+sort by date
+sort by date desc
+list
+done 3
+sort by done
+sort by done asc
+sort by done desc
+list
 bye
diff --git a/text-ui-test/runtest.sh b/text-ui-test/runtest.sh
index 450fb1c3..607729ac 100755
--- a/text-ui-test/runtest.sh
+++ b/text-ui-test/runtest.sh
@@ -19,7 +19,7 @@ then
 fi
 
 # compile the code into the bin folder, terminates if error occurred
-if ! bazel build //:TerminalDuke 
+if ! USE_BAZEL_VERSION=ac9353fab161efae4af72e73fbb657a762b3620d bazelisk run //:TerminalDuke
 then
     echo "********** BUILD FAILURE **********"
     exit 1

From 50d0cce867ea6301bbbc960ca7ff2b543f10a9b1 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Mon, 25 Oct 2021 00:23:51 +0800
Subject: [PATCH 27/32] Basic implementation for Level-9: find feature. (#13)

---
 .../query/SimpleQueryInterpreter.java         |  2 ++
 .../lockarhythm/query/find/FindResponder.java | 28 +++++++++++++++++++
 .../java/com/lockarhythm/tasks/TaskList.java  | 13 +++++++++
 text-ui-test/EXPECTED.TXT                     | 11 ++++++++
 text-ui-test/input.txt                        |  2 ++
 text-ui-test/runtest.sh                       |  2 +-
 6 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/com/lockarhythm/query/find/FindResponder.java

diff --git a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
index 417edf61..169a7118 100644
--- a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
+++ b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
@@ -8,6 +8,7 @@
 import com.lockarhythm.query.todo.TodoResponder;
 import com.lockarhythm.query.delete.DeleteResponder;
 import com.lockarhythm.query.sort.SortResponder;
+import com.lockarhythm.query.find.FindResponder;
 import com.lockarhythm.tasks.TaskList;
 
 /** SimpleQueryInterpreter finds the first QueryInterpreter that responds a non-null result. */
@@ -24,6 +25,7 @@ public SimpleQueryInterpreter(TaskList list) {
       new EventResponder(list),
       new DeleteResponder(list),
       new SortResponder(list),
+      new FindResponder(list),
     };
     interpreters = res;
   }
diff --git a/src/main/java/com/lockarhythm/query/find/FindResponder.java b/src/main/java/com/lockarhythm/query/find/FindResponder.java
new file mode 100644
index 00000000..0b9bf4e1
--- /dev/null
+++ b/src/main/java/com/lockarhythm/query/find/FindResponder.java
@@ -0,0 +1,28 @@
+package com.lockarhythm.query.find;
+
+import com.lockarhythm.query.RegexQueryInterpreter;
+import com.lockarhythm.query.Result;
+import com.lockarhythm.tasks.TaskList;
+
+public class FindResponder extends RegexQueryInterpreter {
+  private TaskList list;
+
+  public FindResponder(TaskList list) {
+    this.list = list;
+  }
+
+  protected String commandRegex() {
+    return "^find (.*)$";
+  }
+
+  public Result onMatch(String[] groups) {
+    String query = groups[1];
+
+    TaskList filteredList = list.find(query);
+
+    if (filteredList.size() == 0) {
+      return new Result(String.format("I could not find any tasks matching your query '%s'", query));
+    }
+    return new Result(String.format("Ok! I have found these tasks for your query '%s'!\n%s", query, filteredList));
+  }
+}
diff --git a/src/main/java/com/lockarhythm/tasks/TaskList.java b/src/main/java/com/lockarhythm/tasks/TaskList.java
index 299a7dd0..a4418922 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskList.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskList.java
@@ -75,6 +75,19 @@ public TaskList sortByDone(boolean isAscending) {
     return new TaskList(copy);
   }
 
+  /**
+   * Returns a new TaskList that matches the given "query" string.
+   */
+  public TaskList find(String query) {
+    ArrayList<Task> filtered = new ArrayList<Task>();
+    for (Task task : list) {
+      if (task.getDescription().contains(query)) {
+        filtered.add(task);
+      }
+    }
+    return new TaskList(filtered);
+  }
+
   @Override
   public String toString() {
     StringBuilder s = new StringBuilder();
diff --git a/text-ui-test/EXPECTED.TXT b/text-ui-test/EXPECTED.TXT
index 1f1854db..48ec722b 100644
--- a/text-ui-test/EXPECTED.TXT
+++ b/text-ui-test/EXPECTED.TXT
@@ -190,6 +190,17 @@
 
 	____________________________________________________________
 
+	____________________________________________________________
+	Ok! I have found these tasks for your query 'bread'!
+	1.[E][ ] buy bread (at: Nov 30 2021)
+
+	____________________________________________________________
+
+	____________________________________________________________
+	I could not find any tasks matching your query 'answer2life'
+
+	____________________________________________________________
+
 	____________________________________________________________
 	Bye. Hope to see you again soon!
 
diff --git a/text-ui-test/input.txt b/text-ui-test/input.txt
index 0369d4ae..08540a85 100644
--- a/text-ui-test/input.txt
+++ b/text-ui-test/input.txt
@@ -22,4 +22,6 @@ sort by done
 sort by done asc
 sort by done desc
 list
+find bread
+find answer2life
 bye
diff --git a/text-ui-test/runtest.sh b/text-ui-test/runtest.sh
index 607729ac..7489bc9c 100755
--- a/text-ui-test/runtest.sh
+++ b/text-ui-test/runtest.sh
@@ -19,7 +19,7 @@ then
 fi
 
 # compile the code into the bin folder, terminates if error occurred
-if ! USE_BAZEL_VERSION=ac9353fab161efae4af72e73fbb657a762b3620d bazelisk run //:TerminalDuke
+if ! USE_BAZEL_VERSION=ac9353fab161efae4af72e73fbb657a762b3620d bazelisk build //:TerminalDuke
 then
     echo "********** BUILD FAILURE **********"
     exit 1

From 11ef984fcfaba268c4b2877d489f8f521cf65edb Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Mon, 25 Oct 2021 01:35:21 +0800
Subject: [PATCH 28/32] Use NLP for dates parsing and include time in
 formatting. (#14)

* Better dates parsing and formatting.
* Fix test command.
---
 BUILD                                         |   2 +
 WORKSPACE                                     |   3 +-
 .../java/com/lockarhythm/tasks/TaskDate.java  |  15 ++-
 text-ui-test/EXPECTED.TXT                     | 125 +++++++++++-------
 text-ui-test/EXPECTED.json                    |  18 ++-
 text-ui-test/input.txt                        |   4 +-
 6 files changed, 111 insertions(+), 56 deletions(-)

diff --git a/BUILD b/BUILD
index 8b8c4a6c..d1bae7dc 100644
--- a/BUILD
+++ b/BUILD
@@ -8,6 +8,7 @@ java_binary(
     deps = [
         "@maven//:org_apache_commons_commons_lang3",
         "@maven//:com_google_code_gson_gson",
+        "@maven//:org_ocpsoft_prettytime_prettytime_nlp",
         ]
 )
 
@@ -22,6 +23,7 @@ java_binary(
     deps = [
         "@maven//:org_apache_commons_commons_lang3",
         "@maven//:com_google_code_gson_gson",
+        "@maven//:org_ocpsoft_prettytime_prettytime_nlp",
         ]
   )
   for class_name in [
diff --git a/WORKSPACE b/WORKSPACE
index 960a9371..7c359742 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -16,7 +16,8 @@ maven_install(
     artifacts = [
         #"com.google.guava:guava:21.0",
         "org.apache.commons:commons-lang3:3.11",
-        "com.google.code.gson:gson:2.8.8"
+        "com.google.code.gson:gson:2.8.8",
+        "org.ocpsoft.prettytime:prettytime-nlp:5.0.2.Final"
     ],
     repositories = [
         # Private repositories are supported through HTTP Basic auth
diff --git a/src/main/java/com/lockarhythm/tasks/TaskDate.java b/src/main/java/com/lockarhythm/tasks/TaskDate.java
index 2dd89b18..96e5efb6 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskDate.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskDate.java
@@ -3,11 +3,20 @@
 import java.io.Serializable;
 import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
+import org.ocpsoft.prettytime.nlp.PrettyTimeParser;
+import java.util.Date;
+import java.util.List;
+import java.time.ZoneId;
 
 class TaskDate implements Serializable {
   private LocalDateTime d;
 
   public TaskDate(String s) {
+    List<Date> dates = new PrettyTimeParser().parse(s);
+    if (dates.size() > 0) {
+      d = toLocalDateTime(dates.get(0));
+      return;
+    }
     d = LocalDateTime.parse(s);
   }
 
@@ -17,6 +26,10 @@ public static int compare(TaskDate x, TaskDate y) {
 
   @Override
   public String toString() {
-    return d.format(DateTimeFormatter.ofPattern("MMM d yyyy"));
+    return d.format(DateTimeFormatter.ofPattern("MMM d yyyy, HH:mm"));
+  }
+
+  private LocalDateTime toLocalDateTime(Date dateToConvert) {
+      return LocalDateTime.ofInstant(dateToConvert.toInstant(), ZoneId.systemDefault());
   }
 }
diff --git a/text-ui-test/EXPECTED.TXT b/text-ui-test/EXPECTED.TXT
index 48ec722b..11540f9b 100644
--- a/text-ui-test/EXPECTED.TXT
+++ b/text-ui-test/EXPECTED.TXT
@@ -18,26 +18,30 @@
 	____________________________________________________________
 
 	____________________________________________________________
-	Please give me a valid LocalDate pattern: Text '10pm' could not be parsed at index 0
+	Got it. I've added this task:
+		[D][ ] return book (by: Oct 25 2021, 22:00)
+	Now you have 2 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
-	Please give me a valid LocalDate pattern: Text 'Sunday 11pm' could not be parsed at index 0
+	Got it. I've added this task:
+		[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	Now you have 3 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Got it. I've added this task:
-		[D][ ] return book (by: Dec 31 2021)
-	Now you have 2 tasks in the list.
+		[D][ ] return book (by: Dec 31 2021, 23:59)
+	Now you have 4 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Got it. I've added this task:
-		[E][ ] buy bread (at: Nov 30 2021)
-	Now you have 3 tasks in the list.
+		[E][ ] buy bread (at: Nov 30 2021, 23:59)
+	Now you have 5 tasks in the list.
 
 	____________________________________________________________
 
@@ -50,36 +54,40 @@
 	____________________________________________________________
 	Here are the tasks in your list:
 	1.[T][X] borrow book
-	2.[D][ ] return book (by: Dec 31 2021)
-	3.[E][ ] buy bread (at: Nov 30 2021)
+	2.[D][ ] return book (by: Oct 25 2021, 22:00)
+	3.[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	4.[D][ ] return book (by: Dec 31 2021, 23:59)
+	5.[E][ ] buy bread (at: Nov 30 2021, 23:59)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Nice! I've marked this task as done:
-		[D][X] return book (by: Dec 31 2021)
+		[D][X] return book (by: Oct 25 2021, 22:00)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Nice! I've marked this task as done:
-		[D][X] return book (by: Dec 31 2021)
+		[D][X] return book (by: Oct 25 2021, 22:00)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Got it. I've added this task:
 		[T][ ] done 1
-	Now you have 4 tasks in the list.
+	Now you have 6 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Here are the tasks in your list:
 	1.[T][X] borrow book
-	2.[D][X] return book (by: Dec 31 2021)
-	3.[E][ ] buy bread (at: Nov 30 2021)
-	4.[T][ ] done 1
+	2.[D][X] return book (by: Oct 25 2021, 22:00)
+	3.[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	4.[D][ ] return book (by: Dec 31 2021, 23:59)
+	5.[E][ ] buy bread (at: Nov 30 2021, 23:59)
+	6.[T][ ] done 1
 
 	____________________________________________________________
 
@@ -95,32 +103,34 @@
 
 	____________________________________________________________
 	Noted. I've removed this task:
-		[D][X] return book (by: Dec 31 2021)
-	Now you have 3 tasks in the list.
+		[D][X] return book (by: Oct 25 2021, 22:00)
+	Now you have 5 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Got it. I've added this task:
-		[E][ ] this task is so 2008 (at: Oct 31 2008)
-	Now you have 4 tasks in the list.
+		[E][ ] this task is so 2008 (at: Oct 31 2008, 23:59)
+	Now you have 6 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Got it. I've added this task:
-		[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
-	Now you have 5 tasks in the list.
+		[E][ ] this task is so 2000-and-late (at: Dec 31 2000, 23:59)
+	Now you have 7 tasks in the list.
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Ok! I have sorted the tasks by date in ascending order!
-	1.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
-	2.[E][ ] this task is so 2008 (at: Oct 31 2008)
-	3.[E][ ] buy bread (at: Nov 30 2021)
-	4.[T][X] borrow book
-	5.[T][ ] done 1
+	1.[E][ ] this task is so 2000-and-late (at: Dec 31 2000, 23:59)
+	2.[E][ ] this task is so 2008 (at: Oct 31 2008, 23:59)
+	3.[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	4.[E][ ] buy bread (at: Nov 30 2021, 23:59)
+	5.[D][ ] return book (by: Dec 31 2021, 23:59)
+	6.[T][X] borrow book
+	7.[T][ ] done 1
 
 	____________________________________________________________
 
@@ -128,71 +138,84 @@
 	Ok! I have sorted the tasks by date in descending order!
 	1.[T][X] borrow book
 	2.[T][ ] done 1
-	3.[E][ ] buy bread (at: Nov 30 2021)
-	4.[E][ ] this task is so 2008 (at: Oct 31 2008)
-	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+	3.[D][ ] return book (by: Dec 31 2021, 23:59)
+	4.[E][ ] buy bread (at: Nov 30 2021, 23:59)
+	5.[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	6.[E][ ] this task is so 2008 (at: Oct 31 2008, 23:59)
+	7.[E][ ] this task is so 2000-and-late (at: Dec 31 2000, 23:59)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Here are the tasks in your list:
 	1.[T][X] borrow book
-	2.[E][ ] buy bread (at: Nov 30 2021)
-	3.[T][ ] done 1
-	4.[E][ ] this task is so 2008 (at: Oct 31 2008)
-	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+	2.[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	3.[D][ ] return book (by: Dec 31 2021, 23:59)
+	4.[E][ ] buy bread (at: Nov 30 2021, 23:59)
+	5.[T][ ] done 1
+	6.[E][ ] this task is so 2008 (at: Oct 31 2008, 23:59)
+	7.[E][ ] this task is so 2000-and-late (at: Dec 31 2000, 23:59)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Nice! I've marked this task as done:
-		[T][X] done 1
+		[D][X] return book (by: Dec 31 2021, 23:59)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Ok! I have sorted the tasks by done in ascending order!
 	1.[T][X] borrow book
-	2.[T][X] done 1
-	3.[E][ ] buy bread (at: Nov 30 2021)
-	4.[E][ ] this task is so 2008 (at: Oct 31 2008)
-	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+	2.[D][X] return book (by: Dec 31 2021, 23:59)
+	3.[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	4.[E][ ] buy bread (at: Nov 30 2021, 23:59)
+	5.[T][ ] done 1
+	6.[E][ ] this task is so 2008 (at: Oct 31 2008, 23:59)
+	7.[E][ ] this task is so 2000-and-late (at: Dec 31 2000, 23:59)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Ok! I have sorted the tasks by done in ascending order!
 	1.[T][X] borrow book
-	2.[T][X] done 1
-	3.[E][ ] buy bread (at: Nov 30 2021)
-	4.[E][ ] this task is so 2008 (at: Oct 31 2008)
-	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+	2.[D][X] return book (by: Dec 31 2021, 23:59)
+	3.[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	4.[E][ ] buy bread (at: Nov 30 2021, 23:59)
+	5.[T][ ] done 1
+	6.[E][ ] this task is so 2008 (at: Oct 31 2008, 23:59)
+	7.[E][ ] this task is so 2000-and-late (at: Dec 31 2000, 23:59)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Ok! I have sorted the tasks by done in descending order!
-	1.[E][ ] buy bread (at: Nov 30 2021)
-	2.[E][ ] this task is so 2008 (at: Oct 31 2008)
-	3.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
-	4.[T][X] borrow book
-	5.[T][X] done 1
+	1.[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	2.[E][ ] buy bread (at: Nov 30 2021, 23:59)
+	3.[T][ ] done 1
+	4.[E][ ] this task is so 2008 (at: Oct 31 2008, 23:59)
+	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000, 23:59)
+	6.[T][X] borrow book
+	7.[D][X] return book (by: Dec 31 2021, 23:59)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Here are the tasks in your list:
 	1.[T][X] borrow book
-	2.[E][ ] buy bread (at: Nov 30 2021)
-	3.[T][X] done 1
-	4.[E][ ] this task is so 2008 (at: Oct 31 2008)
-	5.[E][ ] this task is so 2000-and-late (at: Dec 31 2000)
+	2.[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	3.[D][X] return book (by: Dec 31 2021, 23:59)
+	4.[E][ ] buy bread (at: Nov 30 2021, 23:59)
+	5.[T][ ] done 1
+	6.[E][ ] this task is so 2008 (at: Oct 31 2008, 23:59)
+	7.[E][ ] this task is so 2000-and-late (at: Dec 31 2000, 23:59)
 
 	____________________________________________________________
 
 	____________________________________________________________
 	Ok! I have found these tasks for your query 'bread'!
-	1.[E][ ] buy bread (at: Nov 30 2021)
+	1.[E][ ] buy bread (at: Oct 25 2021, 08:00)
+	2.[E][ ] buy bread (at: Nov 30 2021, 23:59)
 
 	____________________________________________________________
 
diff --git a/text-ui-test/EXPECTED.json b/text-ui-test/EXPECTED.json
index 19d2198c..86afcdee 100644
--- a/text-ui-test/EXPECTED.json
+++ b/text-ui-test/EXPECTED.json
@@ -4,6 +4,22 @@
     "description": "borrow book",
     "isDone": true
   },
+  {
+    "at": {
+      "d": "2021-10-25T08:00:00"
+    },
+    "_type": "EVENT",
+    "description": "buy bread",
+    "isDone": false
+  },
+  {
+    "by": {
+      "d": "2021-12-31T23:59:59"
+    },
+    "_type": "DEADLINE",
+    "description": "return book",
+    "isDone": true
+  },
   {
     "at": {
       "d": "2021-11-30T23:59:59"
@@ -15,7 +31,7 @@
   {
     "_type": "TODO",
     "description": "done 1",
-    "isDone": true
+    "isDone": false
   },
   {
     "at": {
diff --git a/text-ui-test/input.txt b/text-ui-test/input.txt
index 08540a85..1d8120d4 100644
--- a/text-ui-test/input.txt
+++ b/text-ui-test/input.txt
@@ -1,6 +1,6 @@
 todo borrow book
-deadline return book /by 10pm
-event buy bread /at Sunday 11pm
+deadline return book /by Oct 25 10pm
+event buy bread /at Oct 25 morning
 deadline return book /by 2021-12-31T23:59:59
 event buy bread /at 2021-11-30T23:59:59
 done 1

From 94ad2b65ad49b79c7d5aee01174f933cb6c44546 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Mon, 25 Oct 2021 19:58:54 +0800
Subject: [PATCH 29/32] Run through code formatter. (#15)

---
 .../lockarhythm/application/TerminalDuke.java |  8 +-
 .../lockarhythm/query/AddedTaskResult.java    |  4 +-
 .../com/lockarhythm/query/DukeException.java  |  3 +-
 .../query/RegexQueryInterpreter.java          |  5 +-
 .../query/SimpleQueryInterpreter.java         |  8 +-
 .../query/delete/DeleteResponder.java         |  2 +-
 .../query/event/EventResponder.java           |  7 +-
 .../lockarhythm/query/find/FindResponder.java |  7 +-
 .../lockarhythm/query/list/ListResponder.java |  1 -
 .../query/markasdone/MarkAsDoneResponder.java |  2 +-
 .../lockarhythm/query/sort/SortResponder.java | 16 ++--
 .../lockarhythm/query/todo/TodoResponder.java |  2 +-
 .../lockarhythm/storage/GsonLocalDate.java    | 22 +++---
 .../storage/GsonLocalDateTime.java            | 25 ++++---
 .../java/com/lockarhythm/storage/Storage.java | 36 ++++-----
 src/main/java/com/lockarhythm/tasks/Task.java |  4 +-
 .../java/com/lockarhythm/tasks/TaskDate.java  |  6 +-
 .../lockarhythm/tasks/TaskDeserializer.java   | 73 +++++++++----------
 .../java/com/lockarhythm/tasks/TaskList.java  | 41 +++++------
 19 files changed, 135 insertions(+), 137 deletions(-)

diff --git a/src/main/java/com/lockarhythm/application/TerminalDuke.java b/src/main/java/com/lockarhythm/application/TerminalDuke.java
index 693c6209..a7c6e835 100644
--- a/src/main/java/com/lockarhythm/application/TerminalDuke.java
+++ b/src/main/java/com/lockarhythm/application/TerminalDuke.java
@@ -1,13 +1,13 @@
 package com.lockarhythm.application;
 
 import com.lockarhythm.query.SimpleQueryInterpreter;
-import com.lockarhythm.tasks.TaskList;
+import com.lockarhythm.storage.Storage;
 import com.lockarhythm.tasks.Task;
+import com.lockarhythm.tasks.TaskList;
 import com.lockarhythm.ui.TerminalUI;
-import com.lockarhythm.storage.Storage;
-import java.util.ArrayList;
-import java.nio.file.Paths;
 import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
 
 final class TerminalDuke extends Application {
   public static void main(String[] args) {
diff --git a/src/main/java/com/lockarhythm/query/AddedTaskResult.java b/src/main/java/com/lockarhythm/query/AddedTaskResult.java
index dd000a56..fe81905a 100644
--- a/src/main/java/com/lockarhythm/query/AddedTaskResult.java
+++ b/src/main/java/com/lockarhythm/query/AddedTaskResult.java
@@ -1,7 +1,6 @@
 package com.lockarhythm.query;
 
 import com.lockarhythm.tasks.Task;
-import com.lockarhythm.tasks.TaskList;
 
 public class AddedTaskResult extends Result {
   private Task task;
@@ -16,7 +15,6 @@ public AddedTaskResult(Task task, int size) {
   @Override
   public String getText() {
     return String.format(
-          "Got it. I've added this task:\n\t%s\nNow you have %d tasks in the list.",
-          task, size);
+        "Got it. I've added this task:\n\t%s\nNow you have %d tasks in the list.", task, size);
   }
 }
diff --git a/src/main/java/com/lockarhythm/query/DukeException.java b/src/main/java/com/lockarhythm/query/DukeException.java
index a6756f5e..42f0711f 100644
--- a/src/main/java/com/lockarhythm/query/DukeException.java
+++ b/src/main/java/com/lockarhythm/query/DukeException.java
@@ -1,4 +1,3 @@
 package com.lockarhythm.query;
 
-public class DukeException extends Exception {
-}
+public class DukeException extends Exception {}
diff --git a/src/main/java/com/lockarhythm/query/RegexQueryInterpreter.java b/src/main/java/com/lockarhythm/query/RegexQueryInterpreter.java
index 8c5484f2..1c19bd8e 100644
--- a/src/main/java/com/lockarhythm/query/RegexQueryInterpreter.java
+++ b/src/main/java/com/lockarhythm/query/RegexQueryInterpreter.java
@@ -19,14 +19,15 @@ public Result interpret(String query) {
   }
 
   private String[] toGroupStrings(Matcher matcher) {
-    String[] groups = new String[matcher.groupCount()+1];
+    String[] groups = new String[matcher.groupCount() + 1];
     for (int i = 0; i <= matcher.groupCount(); i++) {
       groups[i] = matcher.group(i);
     }
     return groups;
   }
 
-  // onMatch is called when regexp pattern matches. The regexp capturing groups is passed as arguments.
+  // onMatch is called when regexp pattern matches. The regexp capturing groups is passed as
+  // arguments.
   public abstract Result onMatch(String[] groups);
 
   protected abstract String commandRegex();
diff --git a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
index 169a7118..b7dc2e39 100644
--- a/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
+++ b/src/main/java/com/lockarhythm/query/SimpleQueryInterpreter.java
@@ -1,14 +1,14 @@
 package com.lockarhythm.query;
 
-import com.lockarhythm.query.list.ListResponder;
 import com.lockarhythm.query.deadline.DeadlineResponder;
+import com.lockarhythm.query.delete.DeleteResponder;
 import com.lockarhythm.query.event.EventResponder;
 import com.lockarhythm.query.exit.ExitResponder;
+import com.lockarhythm.query.find.FindResponder;
+import com.lockarhythm.query.list.ListResponder;
 import com.lockarhythm.query.markasdone.MarkAsDoneResponder;
-import com.lockarhythm.query.todo.TodoResponder;
-import com.lockarhythm.query.delete.DeleteResponder;
 import com.lockarhythm.query.sort.SortResponder;
-import com.lockarhythm.query.find.FindResponder;
+import com.lockarhythm.query.todo.TodoResponder;
 import com.lockarhythm.tasks.TaskList;
 
 /** SimpleQueryInterpreter finds the first QueryInterpreter that responds a non-null result. */
diff --git a/src/main/java/com/lockarhythm/query/delete/DeleteResponder.java b/src/main/java/com/lockarhythm/query/delete/DeleteResponder.java
index 835e04fc..7dfa9b10 100644
--- a/src/main/java/com/lockarhythm/query/delete/DeleteResponder.java
+++ b/src/main/java/com/lockarhythm/query/delete/DeleteResponder.java
@@ -1,8 +1,8 @@
 package com.lockarhythm.query.delete;
 
+import com.lockarhythm.query.DeletedTaskResult;
 import com.lockarhythm.query.RegexQueryInterpreter;
 import com.lockarhythm.query.Result;
-import com.lockarhythm.query.DeletedTaskResult;
 import com.lockarhythm.tasks.Task;
 import com.lockarhythm.tasks.TaskList;
 
diff --git a/src/main/java/com/lockarhythm/query/event/EventResponder.java b/src/main/java/com/lockarhythm/query/event/EventResponder.java
index 6db6f085..2a8a088d 100644
--- a/src/main/java/com/lockarhythm/query/event/EventResponder.java
+++ b/src/main/java/com/lockarhythm/query/event/EventResponder.java
@@ -1,8 +1,8 @@
 package com.lockarhythm.query.event;
 
+import com.lockarhythm.query.AddedTaskResult;
 import com.lockarhythm.query.RegexQueryInterpreter;
 import com.lockarhythm.query.Result;
-import com.lockarhythm.query.AddedTaskResult;
 import com.lockarhythm.tasks.Task;
 import com.lockarhythm.tasks.TaskList;
 
@@ -21,8 +21,9 @@ public Result onMatch(String[] groups) {
     try {
       Task task = list.addEventTask(groups[1], groups[2]);
       return new AddedTaskResult(task, list.size());
-    } catch(java.time.format.DateTimeParseException e) {
-      return new Result(String.format("Please give me a valid LocalDate pattern: %s", e.getMessage()));
+    } catch (java.time.format.DateTimeParseException e) {
+      return new Result(
+          String.format("Please give me a valid LocalDate pattern: %s", e.getMessage()));
     }
   }
 }
diff --git a/src/main/java/com/lockarhythm/query/find/FindResponder.java b/src/main/java/com/lockarhythm/query/find/FindResponder.java
index 0b9bf4e1..0ef60507 100644
--- a/src/main/java/com/lockarhythm/query/find/FindResponder.java
+++ b/src/main/java/com/lockarhythm/query/find/FindResponder.java
@@ -21,8 +21,11 @@ public Result onMatch(String[] groups) {
     TaskList filteredList = list.find(query);
 
     if (filteredList.size() == 0) {
-      return new Result(String.format("I could not find any tasks matching your query '%s'", query));
+      return new Result(
+          String.format("I could not find any tasks matching your query '%s'", query));
     }
-    return new Result(String.format("Ok! I have found these tasks for your query '%s'!\n%s", query, filteredList));
+    return new Result(
+        String.format(
+            "Ok! I have found these tasks for your query '%s'!\n%s", query, filteredList));
   }
 }
diff --git a/src/main/java/com/lockarhythm/query/list/ListResponder.java b/src/main/java/com/lockarhythm/query/list/ListResponder.java
index 13077612..ba52a90c 100644
--- a/src/main/java/com/lockarhythm/query/list/ListResponder.java
+++ b/src/main/java/com/lockarhythm/query/list/ListResponder.java
@@ -2,7 +2,6 @@
 
 import com.lockarhythm.query.QueryInterpreter;
 import com.lockarhythm.query.Result;
-import com.lockarhythm.tasks.Task;
 import com.lockarhythm.tasks.TaskList;
 
 public final class ListResponder implements QueryInterpreter {
diff --git a/src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java b/src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java
index c9c330b4..bcb629c2 100644
--- a/src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java
+++ b/src/main/java/com/lockarhythm/query/markasdone/MarkAsDoneResponder.java
@@ -21,7 +21,7 @@ public Result onMatch(String[] groups) {
     try {
       Task task = list.markAsDone(i - 1);
       return new Result("Nice! I've marked this task as done:\n\t" + task.toString());
-    } catch(IndexOutOfBoundsException e) {
+    } catch (IndexOutOfBoundsException e) {
       return new Result(String.format("Item %d is not on the list. I cannot mark it as done!", i));
     }
   }
diff --git a/src/main/java/com/lockarhythm/query/sort/SortResponder.java b/src/main/java/com/lockarhythm/query/sort/SortResponder.java
index 71ae7a9b..69b4dc9d 100644
--- a/src/main/java/com/lockarhythm/query/sort/SortResponder.java
+++ b/src/main/java/com/lockarhythm/query/sort/SortResponder.java
@@ -5,7 +5,7 @@
 import com.lockarhythm.tasks.TaskList;
 
 public class SortResponder extends RegexQueryInterpreter {
-  private final static boolean DEFAULT_SORT_ORDER = true;
+  private static final boolean DEFAULT_SORT_ORDER = true;
 
   private TaskList list;
 
@@ -23,7 +23,10 @@ public Result onMatch(String[] groups) {
 
     TaskList sortedList = sortBy(sortKey, isAscending);
 
-    return new Result(String.format("Ok! I have sorted the tasks by %s in %s order!\n%s", sortKey, isAscending ? "ascending" : "descending", sortedList));
+    return new Result(
+        String.format(
+            "Ok! I have sorted the tasks by %s in %s order!\n%s",
+            sortKey, isAscending ? "ascending" : "descending", sortedList));
   }
 
   private boolean parseIsAscending(String value) {
@@ -40,17 +43,16 @@ private boolean parseIsAscending(String value) {
     }
   }
 
-  /**
-   * Sorts by the `sortKey` in the order given by `isAscending`.
-   */
+  /** Sorts by the `sortKey` in the order given by `isAscending`. */
   private TaskList sortBy(String sortKey, boolean isAscending) {
-    switch(sortKey) {
+    switch (sortKey) {
       case "done":
         return list.sortByDone(isAscending);
       case "date":
         return list.sortByTaskDate(isAscending);
       default:
-    };
+    }
+    ;
     return list.sortByTaskDate(isAscending);
   }
 }
diff --git a/src/main/java/com/lockarhythm/query/todo/TodoResponder.java b/src/main/java/com/lockarhythm/query/todo/TodoResponder.java
index 1725ffc0..9e144e27 100644
--- a/src/main/java/com/lockarhythm/query/todo/TodoResponder.java
+++ b/src/main/java/com/lockarhythm/query/todo/TodoResponder.java
@@ -1,7 +1,7 @@
 package com.lockarhythm.query.todo;
 
-import com.lockarhythm.query.RegexQueryInterpreter;
 import com.lockarhythm.query.AddedTaskResult;
+import com.lockarhythm.query.RegexQueryInterpreter;
 import com.lockarhythm.query.Result;
 import com.lockarhythm.tasks.Task;
 import com.lockarhythm.tasks.TaskList;
diff --git a/src/main/java/com/lockarhythm/storage/GsonLocalDate.java b/src/main/java/com/lockarhythm/storage/GsonLocalDate.java
index 7eb94a47..e2fe70bb 100644
--- a/src/main/java/com/lockarhythm/storage/GsonLocalDate.java
+++ b/src/main/java/com/lockarhythm/storage/GsonLocalDate.java
@@ -1,21 +1,23 @@
 package com.lockarhythm.storage;
 
 import com.google.gson.*;
-
 import java.lang.reflect.Type;
 import java.time.LocalDate;
 import java.time.format.DateTimeFormatter;
 
 public class GsonLocalDate implements JsonSerializer<LocalDate>, JsonDeserializer<LocalDate> {
 
-    @Override
-    public LocalDate deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
-        String ldtString = jsonElement.getAsString();
-        return LocalDate.parse(ldtString,DateTimeFormatter.ISO_LOCAL_DATE);
-    }
+  @Override
+  public LocalDate deserialize(
+      JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext)
+      throws JsonParseException {
+    String ldtString = jsonElement.getAsString();
+    return LocalDate.parse(ldtString, DateTimeFormatter.ISO_LOCAL_DATE);
+  }
 
-    @Override
-    public JsonElement serialize(LocalDate localDate, Type type, JsonSerializationContext jsonSerializationContext) {
-        return new JsonPrimitive(localDate.format(DateTimeFormatter.ISO_LOCAL_DATE));
-    }
+  @Override
+  public JsonElement serialize(
+      LocalDate localDate, Type type, JsonSerializationContext jsonSerializationContext) {
+    return new JsonPrimitive(localDate.format(DateTimeFormatter.ISO_LOCAL_DATE));
+  }
 }
diff --git a/src/main/java/com/lockarhythm/storage/GsonLocalDateTime.java b/src/main/java/com/lockarhythm/storage/GsonLocalDateTime.java
index 95878f75..1fea45ef 100644
--- a/src/main/java/com/lockarhythm/storage/GsonLocalDateTime.java
+++ b/src/main/java/com/lockarhythm/storage/GsonLocalDateTime.java
@@ -1,21 +1,24 @@
 package com.lockarhythm.storage;
 
 import com.google.gson.*;
-
 import java.lang.reflect.Type;
 import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
 
-public class GsonLocalDateTime implements JsonSerializer<LocalDateTime>, JsonDeserializer<LocalDateTime> {
+public class GsonLocalDateTime
+    implements JsonSerializer<LocalDateTime>, JsonDeserializer<LocalDateTime> {
 
-    @Override
-    public LocalDateTime deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
-        String ldtString = jsonElement.getAsString();
-        return LocalDateTime.parse(ldtString,DateTimeFormatter.ISO_LOCAL_DATE_TIME);
-    }
+  @Override
+  public LocalDateTime deserialize(
+      JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext)
+      throws JsonParseException {
+    String ldtString = jsonElement.getAsString();
+    return LocalDateTime.parse(ldtString, DateTimeFormatter.ISO_LOCAL_DATE_TIME);
+  }
 
-    @Override
-    public JsonElement serialize(LocalDateTime localDateTime, Type type, JsonSerializationContext jsonSerializationContext) {
-        return new JsonPrimitive(localDateTime.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME));
-    }
+  @Override
+  public JsonElement serialize(
+      LocalDateTime localDateTime, Type type, JsonSerializationContext jsonSerializationContext) {
+    return new JsonPrimitive(localDateTime.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME));
+  }
 }
diff --git a/src/main/java/com/lockarhythm/storage/Storage.java b/src/main/java/com/lockarhythm/storage/Storage.java
index 052d2e04..4413ea66 100644
--- a/src/main/java/com/lockarhythm/storage/Storage.java
+++ b/src/main/java/com/lockarhythm/storage/Storage.java
@@ -1,24 +1,18 @@
 package com.lockarhythm.storage;
 
-
-import com.google.gson.GsonBuilder;
 import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
 import com.google.gson.reflect.TypeToken;
-import java.lang.reflect.Type;
-import java.time.LocalDateTime;
-import java.time.LocalDate;
-
+import com.lockarhythm.tasks.Task;
+import com.lockarhythm.tasks.TaskDeserializer;
 import java.io.FileOutputStream;
-import java.io.ObjectOutputStream;
 import java.io.IOException;
-import java.io.Serializable;
+import java.lang.reflect.Type;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.charset.StandardCharsets;
-
-import com.lockarhythm.tasks.TaskDeserializer;
-import com.lockarhythm.tasks.Task;
-
+import java.time.LocalDate;
+import java.time.LocalDateTime;
 import java.util.ArrayList;
 
 public class Storage<T> {
@@ -31,12 +25,13 @@ public class Storage<T> {
   public Storage(String filePath) {
     this.filePath = filePath;
 
-    gson = new GsonBuilder()
-      .registerTypeAdapter(Task.class, new TaskDeserializer("_type"))
-      .registerTypeAdapter(LocalDateTime.class, new GsonLocalDateTime())
-      .registerTypeAdapter(LocalDate.class, new GsonLocalDate())
-      .setPrettyPrinting()
-      .create();
+    gson =
+        new GsonBuilder()
+            .registerTypeAdapter(Task.class, new TaskDeserializer("_type"))
+            .registerTypeAdapter(LocalDateTime.class, new GsonLocalDateTime())
+            .registerTypeAdapter(LocalDate.class, new GsonLocalDate())
+            .setPrettyPrinting()
+            .create();
   }
 
   public void registerList(ArrayList<T> list) {
@@ -49,7 +44,8 @@ public ArrayList<T> load(Class<T> type) {
       content = Files.readString(Path.of(filePath), StandardCharsets.UTF_8);
 
       Type typeOfT = TypeToken.getParameterized(ArrayList.class, type).getType();
-      ArrayList<T> deserialized = gson.fromJson(content, new TypeToken<ArrayList<Task>>(){}.getType());
+      ArrayList<T> deserialized =
+          gson.fromJson(content, new TypeToken<ArrayList<Task>>() {}.getType());
       if (deserialized == null) {
         return new ArrayList<T>();
       }
diff --git a/src/main/java/com/lockarhythm/tasks/Task.java b/src/main/java/com/lockarhythm/tasks/Task.java
index e140b65f..4a739823 100644
--- a/src/main/java/com/lockarhythm/tasks/Task.java
+++ b/src/main/java/com/lockarhythm/tasks/Task.java
@@ -3,8 +3,8 @@
 import java.io.Serializable;
 
 public abstract class Task implements Serializable {
-  private transient static String DEFAULT_TASK_DATE_VALUE = "3000-12-31T23:59:59";
-  private transient static TaskDate DEFAULT_TASK_DATE = new TaskDate(DEFAULT_TASK_DATE_VALUE);
+  private static transient String DEFAULT_TASK_DATE_VALUE = "3000-12-31T23:59:59";
+  private static transient TaskDate DEFAULT_TASK_DATE = new TaskDate(DEFAULT_TASK_DATE_VALUE);
 
   private String description;
   private boolean isDone;
diff --git a/src/main/java/com/lockarhythm/tasks/TaskDate.java b/src/main/java/com/lockarhythm/tasks/TaskDate.java
index 96e5efb6..46552183 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskDate.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskDate.java
@@ -2,11 +2,11 @@
 
 import java.io.Serializable;
 import java.time.LocalDateTime;
+import java.time.ZoneId;
 import java.time.format.DateTimeFormatter;
-import org.ocpsoft.prettytime.nlp.PrettyTimeParser;
 import java.util.Date;
 import java.util.List;
-import java.time.ZoneId;
+import org.ocpsoft.prettytime.nlp.PrettyTimeParser;
 
 class TaskDate implements Serializable {
   private LocalDateTime d;
@@ -30,6 +30,6 @@ public String toString() {
   }
 
   private LocalDateTime toLocalDateTime(Date dateToConvert) {
-      return LocalDateTime.ofInstant(dateToConvert.toInstant(), ZoneId.systemDefault());
+    return LocalDateTime.ofInstant(dateToConvert.toInstant(), ZoneId.systemDefault());
   }
 }
diff --git a/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java b/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java
index a00f4b0b..d157e563 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskDeserializer.java
@@ -1,47 +1,44 @@
 package com.lockarhythm.tasks;
 
 import com.google.gson.*;
-import java.lang.reflect.Type;
-import java.util.HashMap;
-import java.util.Map;
-
-import com.lockarhythm.storage.GsonLocalDateTime;
 import com.lockarhythm.storage.GsonLocalDate;
+import com.lockarhythm.storage.GsonLocalDateTime;
+import java.lang.reflect.Type;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
-import java.time.format.DateTimeFormatter;
+import java.util.HashMap;
+import java.util.Map;
 
-/**
- * Technique credit to https://www.baeldung.com/gson-list
- */
+/** Technique credit to https://www.baeldung.com/gson-list */
 public class TaskDeserializer implements JsonDeserializer<Task> {
-    private String taskTypeElementName;
-    private Gson gson;
-    private Map<String, Class<? extends Task>> taskTypeRegistry;
-
-    public TaskDeserializer(String taskTypeElementName) {
-        this.gson = new GsonBuilder()
-          .registerTypeAdapter(LocalDateTime.class, new GsonLocalDateTime())
-          .registerTypeAdapter(LocalDate.class, new GsonLocalDate())
-          .create();
-
-        this.taskTypeElementName = taskTypeElementName;
-        this.taskTypeRegistry = new HashMap<>();
-
-        this.registerTaskType("DEADLINE", DeadlineTask.class);
-        this.registerTaskType("TODO", TodoTask.class);
-        this.registerTaskType("EVENT", EventTask.class);
-    }
-
-    public void registerTaskType(String taskTypeName, Class<? extends Task> taskType) {
-        taskTypeRegistry.put(taskTypeName, taskType);
-    }
-
-    public Task deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) {
-        JsonObject taskObject = json.getAsJsonObject();
-        JsonElement taskTypeElement = taskObject.get(taskTypeElementName);
-
-        Class<? extends Task> taskType = taskTypeRegistry.get(taskTypeElement.getAsString());
-        return gson.fromJson(taskObject, taskType);
-    }
+  private String taskTypeElementName;
+  private Gson gson;
+  private Map<String, Class<? extends Task>> taskTypeRegistry;
+
+  public TaskDeserializer(String taskTypeElementName) {
+    this.gson =
+        new GsonBuilder()
+            .registerTypeAdapter(LocalDateTime.class, new GsonLocalDateTime())
+            .registerTypeAdapter(LocalDate.class, new GsonLocalDate())
+            .create();
+
+    this.taskTypeElementName = taskTypeElementName;
+    this.taskTypeRegistry = new HashMap<>();
+
+    this.registerTaskType("DEADLINE", DeadlineTask.class);
+    this.registerTaskType("TODO", TodoTask.class);
+    this.registerTaskType("EVENT", EventTask.class);
+  }
+
+  public void registerTaskType(String taskTypeName, Class<? extends Task> taskType) {
+    taskTypeRegistry.put(taskTypeName, taskType);
+  }
+
+  public Task deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) {
+    JsonObject taskObject = json.getAsJsonObject();
+    JsonElement taskTypeElement = taskObject.get(taskTypeElementName);
+
+    Class<? extends Task> taskType = taskTypeRegistry.get(taskTypeElement.getAsString());
+    return gson.fromJson(taskObject, taskType);
+  }
 }
diff --git a/src/main/java/com/lockarhythm/tasks/TaskList.java b/src/main/java/com/lockarhythm/tasks/TaskList.java
index a4418922..1709accc 100644
--- a/src/main/java/com/lockarhythm/tasks/TaskList.java
+++ b/src/main/java/com/lockarhythm/tasks/TaskList.java
@@ -1,7 +1,6 @@
 package com.lockarhythm.tasks;
 
 import java.util.ArrayList;
-import java.util.Comparator;
 import java.util.Collections;
 
 public class TaskList {
@@ -47,37 +46,35 @@ public Task deleteTask(int index) {
     return list.remove(index);
   }
 
-  /**
-   * Returns a copy of TaskList sorted by the task date.
-   */
+  /** Returns a copy of TaskList sorted by the task date. */
   public TaskList sortByTaskDate(boolean isAscending) {
     ArrayList<Task> copy = new ArrayList<Task>(list);
-    Collections.sort(copy, (a, b) -> {
-      if (isAscending) {
-        return TaskDate.compare(a.getTaskDate(), b.getTaskDate());
-      }
-      return TaskDate.compare(b.getTaskDate(), a.getTaskDate());
-    });
+    Collections.sort(
+        copy,
+        (a, b) -> {
+          if (isAscending) {
+            return TaskDate.compare(a.getTaskDate(), b.getTaskDate());
+          }
+          return TaskDate.compare(b.getTaskDate(), a.getTaskDate());
+        });
     return new TaskList(copy);
   }
 
-  /**
-   * Returns a copy of TaskList sorted by the "done" field.
-   */
+  /** Returns a copy of TaskList sorted by the "done" field. */
   public TaskList sortByDone(boolean isAscending) {
     ArrayList<Task> copy = new ArrayList<Task>(list);
-    Collections.sort(copy, (a, b) -> {
-      if (isAscending) {
-        return Boolean.compare(b.isDone(), a.isDone());
-      }
-      return Boolean.compare(a.isDone(), b.isDone());
-    });
+    Collections.sort(
+        copy,
+        (a, b) -> {
+          if (isAscending) {
+            return Boolean.compare(b.isDone(), a.isDone());
+          }
+          return Boolean.compare(a.isDone(), b.isDone());
+        });
     return new TaskList(copy);
   }
 
-  /**
-   * Returns a new TaskList that matches the given "query" string.
-   */
+  /** Returns a new TaskList that matches the given "query" string. */
   public TaskList find(String query) {
     ArrayList<Task> filtered = new ArrayList<Task>();
     for (Task task : list) {

From c401a189948a103ae9d83dbeb174efbcce98fdd5 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Tue, 26 Oct 2021 20:20:26 +0800
Subject: [PATCH 30/32] Fix code quality feedback #16 (#17)

Co-authored-by: Goh Yisheng <mail.yisheng@gmail.com>
---
 src/main/java/com/lockarhythm/query/sort/SortResponder.java | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main/java/com/lockarhythm/query/sort/SortResponder.java b/src/main/java/com/lockarhythm/query/sort/SortResponder.java
index 69b4dc9d..a4f5a744 100644
--- a/src/main/java/com/lockarhythm/query/sort/SortResponder.java
+++ b/src/main/java/com/lockarhythm/query/sort/SortResponder.java
@@ -5,7 +5,7 @@
 import com.lockarhythm.tasks.TaskList;
 
 public class SortResponder extends RegexQueryInterpreter {
-  private static final boolean DEFAULT_SORT_ORDER = true;
+  private static final boolean IS_ASCENDING_DEFAULT = true;
 
   private TaskList list;
 
@@ -31,7 +31,7 @@ public Result onMatch(String[] groups) {
 
   private boolean parseIsAscending(String value) {
     if (value == null) {
-      return DEFAULT_SORT_ORDER;
+      return IS_ASCENDING_DEFAULT;
     }
     String s = value.trim();
     if (s.equals("desc")) {
@@ -39,7 +39,7 @@ private boolean parseIsAscending(String value) {
     } else if (s.equals("asc")) {
       return true;
     } else {
-      return DEFAULT_SORT_ORDER;
+      return IS_ASCENDING_DEFAULT;
     }
   }
 

From fd53b7493e1c2d04d7624e41b9ddaf1e58466ffc Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Tue, 26 Oct 2021 21:09:47 +0800
Subject: [PATCH 31/32] Implement A-Assertions (#18)

* Add assertions.

* Create QA build.

* Fix build.

* Update readme.
---
 BUILD                                         | 20 +++++++++++++++++--
 README.md                                     |  3 +++
 .../lockarhythm/query/sort/SortResponder.java |  1 +
 .../java/com/lockarhythm/ui/TerminalUI.java   |  1 +
 text-ui-test/runtest.sh                       |  4 ++--
 5 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/BUILD b/BUILD
index d1bae7dc..ee30cb50 100644
--- a/BUILD
+++ b/BUILD
@@ -1,7 +1,7 @@
 load("@rules_java//java:defs.bzl", "java_binary", "java_test")
 
 java_binary(
-    name = "TerminalDuke",
+    name = "TerminalDuke", # Production Build.
     srcs = glob([
         "src/main/java/com/lockarhythm/**/*.java",
     ]),
@@ -9,7 +9,23 @@ java_binary(
         "@maven//:org_apache_commons_commons_lang3",
         "@maven//:com_google_code_gson_gson",
         "@maven//:org_ocpsoft_prettytime_prettytime_nlp",
-        ]
+    ],
+)
+
+java_binary(
+    name = "TerminalDukeQA", # QA Build. has assertions enabled.
+    main_class = "com.lockarhythm.application.TerminalDuke",
+    srcs = glob([
+        "src/main/java/com/lockarhythm/**/*.java",
+    ]),
+    deps = [
+        "@maven//:org_apache_commons_commons_lang3",
+        "@maven//:com_google_code_gson_gson",
+        "@maven//:org_ocpsoft_prettytime_prettytime_nlp",
+    ],
+    jvm_flags = [
+        "-enableassertions",
+    ],
 )
 
 [
diff --git a/README.md b/README.md
index a54cf64b..0dfacebc 100644
--- a/README.md
+++ b/README.md
@@ -21,6 +21,9 @@ bazel run //:TerminalDuke
 
 # Use bazelisk for M1 Macs (Apple Silicon)
 USE_BAZEL_VERSION=ac9353fab161efae4af72e73fbb657a762b3620d bazelisk run //:TerminalDuke
+
+# For QA build, for example, having assertions enabled, build TerminalDukeQA instead
+USE_BAZEL_VERSION=ac9353fab161efae4af72e73fbb657a762b3620d bazelisk run //:TerminalDukeQA
 ```
 
 To build jar file for deployment purposes:
diff --git a/src/main/java/com/lockarhythm/query/sort/SortResponder.java b/src/main/java/com/lockarhythm/query/sort/SortResponder.java
index a4f5a744..52ca5e65 100644
--- a/src/main/java/com/lockarhythm/query/sort/SortResponder.java
+++ b/src/main/java/com/lockarhythm/query/sort/SortResponder.java
@@ -51,6 +51,7 @@ private TaskList sortBy(String sortKey, boolean isAscending) {
       case "date":
         return list.sortByTaskDate(isAscending);
       default:
+        assert false : "sortKey is not a valid value. Check command regex.";
     }
     ;
     return list.sortByTaskDate(isAscending);
diff --git a/src/main/java/com/lockarhythm/ui/TerminalUI.java b/src/main/java/com/lockarhythm/ui/TerminalUI.java
index 4c60aad5..396b678d 100644
--- a/src/main/java/com/lockarhythm/ui/TerminalUI.java
+++ b/src/main/java/com/lockarhythm/ui/TerminalUI.java
@@ -25,6 +25,7 @@ public void print(String... strings) {
   }
 
   public void print(Result res) {
+    assert res != null;
     print(res.getText());
   }
 }
diff --git a/text-ui-test/runtest.sh b/text-ui-test/runtest.sh
index 7489bc9c..bbc3283f 100755
--- a/text-ui-test/runtest.sh
+++ b/text-ui-test/runtest.sh
@@ -19,14 +19,14 @@ then
 fi
 
 # compile the code into the bin folder, terminates if error occurred
-if ! USE_BAZEL_VERSION=ac9353fab161efae4af72e73fbb657a762b3620d bazelisk build //:TerminalDuke
+if ! USE_BAZEL_VERSION=ac9353fab161efae4af72e73fbb657a762b3620d bazelisk build //:TerminalDukeQA
 then
     echo "********** BUILD FAILURE **********"
     exit 1
 fi
 
 # run the program, feed commands from input.txt file and redirect the output to the ACTUAL.TXT
-../bazel-bin/TerminalDuke < input.txt > ACTUAL.TXT
+../bazel-bin/TerminalDukeQA < input.txt > ACTUAL.TXT
 
 # convert to UNIX format
 cp EXPECTED.TXT EXPECTED-UNIX.TXT

From ff37085622d1a6d97c8d40a3b7a8f8bcb0fd47f2 Mon Sep 17 00:00:00 2001
From: lockarhythm <88638946+lockarhythm@users.noreply.github.com>
Date: Sun, 14 Nov 2021 23:37:20 +0800
Subject: [PATCH 32/32] Add java docs (#25)

---
 .../lockarhythm/application/Application.java  | 14 +++++++++++
 .../lockarhythm/application/TerminalDuke.java |  3 +++
 .../java/com/lockarhythm/storage/Storage.java | 22 ++++++++++++++++++
 .../java/com/lockarhythm/ui/TerminalUI.java   | 23 +++++++++++++++++++
 src/main/java/com/lockarhythm/ui/UI.java      | 23 +++++++++++++++++++
 5 files changed, 85 insertions(+)

diff --git a/src/main/java/com/lockarhythm/application/Application.java b/src/main/java/com/lockarhythm/application/Application.java
index bc803d17..5ca8f930 100644
--- a/src/main/java/com/lockarhythm/application/Application.java
+++ b/src/main/java/com/lockarhythm/application/Application.java
@@ -7,6 +7,11 @@
 import com.lockarhythm.ui.UI;
 import java.io.IOException;
 
+/**
+ * Application contains the common logic of all Duke Applications (GUI, TUI).
+ *
+ * <p>The application architecture is heavily inspired by the Ports & Adapters architecture.
+ */
 abstract class Application {
   static String logo =
       " \t____        _        \n"
@@ -15,6 +20,15 @@ abstract class Application {
           + "\t| |_| | |_| |   <  __/\n"
           + "\t|____/ \\__,_|_|\\_\\___|\n";
 
+  /**
+   * run should be supplied with concrete implementations of its UI, QueryInterpreter and Storage.
+   *
+   * <p>For example, UI could be the Terminal UI or GUI. Storage could be in-memory or disk.
+   *
+   * @param ui a concrete UI implementation
+   * @param q a concrete QueryInterpreter implementation
+   * @param storage any Storage implementation
+   */
   public static void run(UI ui, QueryInterpreter q, Storage storage) {
     Result result;
 
diff --git a/src/main/java/com/lockarhythm/application/TerminalDuke.java b/src/main/java/com/lockarhythm/application/TerminalDuke.java
index a7c6e835..d961ba6e 100644
--- a/src/main/java/com/lockarhythm/application/TerminalDuke.java
+++ b/src/main/java/com/lockarhythm/application/TerminalDuke.java
@@ -9,6 +9,9 @@
 import java.nio.file.Paths;
 import java.util.ArrayList;
 
+/**
+ * TerminalDuke is the entrypoint of the Terminal UI application of Duke.
+ */
 final class TerminalDuke extends Application {
   public static void main(String[] args) {
     Path path = Paths.get(".", "tasks.json");
diff --git a/src/main/java/com/lockarhythm/storage/Storage.java b/src/main/java/com/lockarhythm/storage/Storage.java
index 4413ea66..c770d632 100644
--- a/src/main/java/com/lockarhythm/storage/Storage.java
+++ b/src/main/java/com/lockarhythm/storage/Storage.java
@@ -15,6 +15,9 @@
 import java.time.LocalDateTime;
 import java.util.ArrayList;
 
+/**
+ * Storage handles all concerns relating to persisting tasks to disk.
+ */
 public class Storage<T> {
   private String filePath;
 
@@ -22,6 +25,11 @@ public class Storage<T> {
 
   private Gson gson;
 
+  /**
+   * Storage constructor takes in filePath as the destination path to write bytes to.
+   *
+   * @param filePath a valid location path to persist the tasks to.
+   */
   public Storage(String filePath) {
     this.filePath = filePath;
 
@@ -34,10 +42,21 @@ public Storage(String filePath) {
             .create();
   }
 
+  /**
+   * registerList is meant to allow top-level Application to pass a reference a the Task List so that Storage can save a reference.
+   *
+   * @param list an array list of tasks to be persisted.
+   */
   public void registerList(ArrayList<T> list) {
     this.list = list;
   }
 
+  /**
+   * load reads the array list of tasks from disk. In order to handle persisting of abstract classes like Task with GSON, we need to pass its class in as parameter.
+   *
+   * @param type to pass the abstract type that is expected.
+   * @return an array list of tasks from disk.
+   */
   public ArrayList<T> load(Class<T> type) {
     String content;
     try {
@@ -55,6 +74,9 @@ public ArrayList<T> load(Class<T> type) {
     }
   }
 
+  /**
+   * overwrite writes the current array list to disk.
+   */
   public void overwrite() throws IOException {
     FileOutputStream fo = new FileOutputStream(filePath);
     String js = gson.toJson(list);
diff --git a/src/main/java/com/lockarhythm/ui/TerminalUI.java b/src/main/java/com/lockarhythm/ui/TerminalUI.java
index 396b678d..084eea25 100644
--- a/src/main/java/com/lockarhythm/ui/TerminalUI.java
+++ b/src/main/java/com/lockarhythm/ui/TerminalUI.java
@@ -4,17 +4,35 @@
 import java.util.Arrays;
 import java.util.Scanner;
 
+/**
+ * TerminalUI is an <i>adapter</i> of UI <i>port</i>.
+ */
 public final class TerminalUI implements UI {
   private static Scanner in = new Scanner(System.in);
 
+  /**
+   * nextLine reads the next line from standard input.
+   *
+   * @return the next line as a string
+   */
   public String nextLine() {
     return in.nextLine();
   }
 
+  /**
+   * hasNext returns true if another line is available in standard input.
+   *
+   * @return true if another line is available. False otherwise.
+   */
   public boolean hasNext() {
     return in.hasNext();
   }
 
+  /**
+   * print formats the given strings and prints to standard output.
+   *
+   * @param strings the list of strings to be printed
+   */
   public void print(String... strings) {
     System.out.println("\t____________________________________________________________");
     for (String s : strings) {
@@ -24,6 +42,11 @@ public void print(String... strings) {
     System.out.println("\t____________________________________________________________\n");
   }
 
+  /**
+   * print formats the given Result and prints to standard output. This is a helper function to handle the common operation of printing results from query interpreters.
+   *
+   * @param res the task Result to print.
+   */
   public void print(Result res) {
     assert res != null;
     print(res.getText());
diff --git a/src/main/java/com/lockarhythm/ui/UI.java b/src/main/java/com/lockarhythm/ui/UI.java
index 3a65d437..33c625f3 100644
--- a/src/main/java/com/lockarhythm/ui/UI.java
+++ b/src/main/java/com/lockarhythm/ui/UI.java
@@ -2,12 +2,35 @@
 
 import com.lockarhythm.query.Result;
 
+/**
+ * UI is a <i>port</i>. An example adapter is the TerminalUI.
+ */
 public interface UI {
+  /**
+   * nextLine returns the next line from the input.
+   *
+   * @return the next line as a string.
+   */
   public String nextLine();
 
+  /**
+   * hasNext returns true if there are more line(s) to be consumed in the next call to nextLine. Returns false otherwise.
+   *
+   * @return true if a new line exists. False otherwise.
+   */
   public boolean hasNext();
 
+  /**
+   * print should print the given strings to the output.
+   *
+   * @param strings a list of strings to be printed
+   */
   public void print(String... strings);
 
+  /**
+   * print is a helper function to print Results to output.
+   *
+   * @param res a task result to print.
+   */
   public void print(Result res);
 }