diff --git a/LICENSE b/LICENSE
index e1a278e..cd41e27 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2018, Dan Ryan <dan@danryan.co>
+Copyright (c) 2018, Dan Ryan <dan@danryan.co> and Tzu-ping Chung <uranusjr@gmail.com>
 
 Permission to use, copy, modify, and distribute this software for any
 purpose with or without fee is hereby granted, provided that the above
diff --git a/Pipfile b/Pipfile
index 25ed7ee..51464ab 100644
--- a/Pipfile
+++ b/Pipfile
@@ -1,5 +1,5 @@
 [packages]
-passa = { editable = true, path = '.' }
+passa = { editable = true, path = '.', extras = ['virtualenv'] }
 
 [dev-packages]
 black = '*'
diff --git a/Pipfile.lock b/Pipfile.lock
index ff1f65c..89c3e2d 100644
--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "ff353680e286436d85c9b1b00ccb7ee257cb2922a1eec0becf9713817605d92b"
+            "sha256": "994d50f9fd0acc91cf216cf0ffc1233ebbfd0a411b57320f44a0f4487943e546"
         },
         "pipfile-spec": 6,
         "requires": {},
@@ -19,36 +19,49 @@
                 "sha256:9e5896d1372858f8dd3344faf4e5014d21849c756c8d5701f78f8a103b372d92",
                 "sha256:d8b24664561d0d34ddfaec54636d502d7cea6e29c3eaf68f3df6180863e2166e"
             ],
-            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3' or python_version >= '3.6'",
             "version": "==1.4.3"
         },
         "attrs": {
             "hashes": [
-                "sha256:4b90b09eeeb9b88c35bc642cbac057e45a5fd85367b985bd2809c62b7b939265",
-                "sha256:e0d0eb91441a3b53dab4d9b743eafc1ac44476296a2053b6ca3af0b139faf87b"
+                "sha256:10cbf6e27dbce8c30807caf056c8eb50917e0eaafe86347671b57254006c3e69",
+                "sha256:ca4be454458f9dec299268d472aaa5a11f67a4ff70093396e1ceae9c76cf4bbb"
             ],
-            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3' or python_version >= '3.6'",
-            "version": "==18.1.0"
+            "version": "==18.2.0"
+        },
+        "backports-functools-lru-cache": {
+            "hashes": [
+                "sha256:f0b0e4eba956de51238e17573b7087e852dfe9854afd2e9c873f73fc0ca0a6dd"
+            ],
+            "markers": "python_version < '2.8' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==1.5"
         },
         "backports-shutil-get-terminal-size": {
             "hashes": [
                 "sha256:0975ba55054c15e346944b38956a4c9cbee9009391e41b86c68990effb8c1f64"
             ],
-            "markers": "python_version < '3.3' and python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version < '3.3' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.0.0"
         },
         "backports-weakref": {
             "hashes": [
                 "sha256:81bc9b51c0abc58edc76aefbbc68c62a787918ffe943a37947e162c3f8e19e82"
             ],
-            "markers": "python_version < '3.3' and python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version < '3.3' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.0.post1"
         },
+        "cached-property": {
+            "hashes": [
+                "sha256:3a026f1a54135677e7da5ce819b0c690f156f37976f3e30c5430740725203d7f",
+                "sha256:9217a59f14a5682da7c4b8829deadbfc194ac22e9908ccf7c8820234e80a1504"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==1.5.1"
+        },
         "cerberus": {
             "hashes": [
                 "sha256:f5c2e048fb15ecb3c088d192164316093fcfa602a74b3386eefb2983aa7e800a"
             ],
-            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.2"
         },
         "certifi": {
@@ -56,7 +69,7 @@
                 "sha256:376690d6f16d32f9d1fe8932551d80b23e9d393a8578c5633a2ed39a64861638",
                 "sha256:456048c7e371c089d0a77a5212fb37a2c2dce1e24146e3b7e0261736aaeaa22a"
             ],
-            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2018.8.24"
         },
         "chardet": {
@@ -64,7 +77,7 @@
                 "sha256:84ab92ed1c4d4f16916e05906b6b75a6c0fb5db821cc65e70cbd64a3e2a5eaae",
                 "sha256:fc323ffcaeaed0e0a02bf4d117757b98aed530d9ed4531e3e15460124c106691"
             ],
-            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==3.0.4"
         },
         "distlib": {
@@ -81,7 +94,7 @@
                 "sha256:6bd0f6ad48ec2aa117d3d141940d484deccda84d4fcd884f5c3d93c23ecd8c79",
                 "sha256:8ad8c4783bf61ded74527bffb48ed9b54166685e4230386a9ed9b1279e2df5b1"
             ],
-            "markers": "python_version >= '2.6' and python_version >= '2.7' and python_version < '2.8' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version < '2.8' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.1.6"
         },
         "first": {
@@ -97,39 +110,47 @@
                 "sha256:156a6814fb5ac1fc6850fb002e0852d56c0c8d2531923a51032d1b70760e186e",
                 "sha256:684a38a6f903c1d71d6d5fac066b58d7768af4de2b832e426ec79c30daa94a16"
             ],
-            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.7"
         },
         "importlib": {
             "hashes": [
                 "sha256:b6ee7066fea66e35f8d0acee24d98006de1a0a8a94a8ce6efe73a9a23c8d9826"
             ],
-            "markers": "python_version < '2.7' and python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version < '2.7' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.0.4"
         },
+        "installer": {
+            "hashes": [
+                "sha256:1ba23de573e9b95a8dcbd04fd026c40a64b77db0aadc48f28a844b4cb87479fe",
+                "sha256:f4f195c9b17ea7d2b631a758451485c6b080975349b4adebe45ef4bb022db069"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==0.1.1"
+        },
         "modutil": {
             "hashes": [
                 "sha256:2c85c1666649e92e56de17c00e1e831313602d9b55e8661d39c01e39003b45f7",
                 "sha256:cc3dad264e36ed359fdd67c4588959d2996bd0402ad9c9d974ca906821537218"
             ],
-            "markers": "python_version >= '2.6' and python_version >= '3.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version >= '3.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.0.0"
         },
-        "more-itertools": {
+        "mork": {
             "hashes": [
-                "sha256:c187a73da93e7a8acc0001572aebc7e3c69daf7bf6881a2cea10650bd4420092",
-                "sha256:c476b5d3a34e12d40130bc2f935028b5f636df8f372dc2c1c01dc19681b2039e",
-                "sha256:fcbfeaea0be121980e15bc97b3817b5202ca73d0eae185b4550cbfce2a3ebb3d"
+                "sha256:2ac3eed13edb8d854b6be470f0126da38514e9fb50b2112e45fc263e846d1576",
+                "sha256:bd16240d34ae4833cffa44b2671306c24fe830456105b908dac34fd31d2017af"
             ],
             "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
-            "version": "==4.3.0"
+            "version": "==0.1.2"
         },
-        "ordereddict": {
+        "packagebuilder": {
             "hashes": [
-                "sha256:1c35b4ac206cef2d24816c89f89cf289dd3d38cf7c449bb3fab7bf6d43f01b1f"
+                "sha256:1e85c4e0e994322996b93cd6685c12834d30f3558889154f8e3de8fb1f3fd1e7",
+                "sha256:dc525d06ecd102db23ab421b879d7d27021d784ff933e33e8c411a53af5c9dbe"
             ],
-            "markers": "python_version < '3.0' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
-            "version": "==1.1"
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==0.1.0"
         },
         "packaging": {
             "hashes": [
@@ -141,7 +162,9 @@
         },
         "passa": {
             "editable": true,
-            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "extras": [
+                "virtualenv"
+            ],
             "path": "."
         },
         "pathlib2": {
@@ -149,7 +172,7 @@
                 "sha256:8eb170f8d0d61825e09a95b38be068299ddeda82f35e96c3301a8a5e7604cb83",
                 "sha256:d1aa2a11ba7b8f7b21ab852b1fb5afb277e1bb99d5dfc663380b5015c0d80c5a"
             ],
-            "markers": "python_version < '3.6' and python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3' or python_version < '3.6' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version < '3.5' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.3.2"
         },
         "pip-shims": {
@@ -157,7 +180,7 @@
                 "sha256:9c8a568b4a8ce4000a2982224f48a35736fca81214dfdb30dcae24287866a7e4",
                 "sha256:ebc2bb29ddd21fa00c0cf28a5d8c725100f2f7ee98703aba237efd02e205c1c1"
             ],
-            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==0.1.2"
         },
         "plette": {
@@ -168,40 +191,48 @@
                 "sha256:c0e3553c1e581d8423daccbd825789c6e7f29b7d9e00e5331b12e1642a1a26d3",
                 "sha256:dde5d525cf5f0cbad4d938c83b93db17887918daf63c13eafed257c4f61b07b4"
             ],
-            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==0.2.2"
         },
         "pyparsing": {
             "hashes": [
-                "sha256:0832bcf47acd283788593e7a0f542407bd9550a55a8a8435214a1960e04bcb04",
-                "sha256:fee43f17a9c4087e7ed1605bd6df994c6173c1e977d7ade7b651292fab2bd010"
+                "sha256:905d8090c335314568b5faee0025b1829f27bb974604a5762a6cdef3a7dfc3b7",
+                "sha256:f493ee323be1e94929416b3585eefcc04943115cecbaaa35a8c86d1a2368af19"
             ],
             "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
-            "version": "==2.2.0"
+            "version": "==2.2.1"
+        },
+        "recursive-monkey-patch": {
+            "hashes": [
+                "sha256:546739fea5be2ea9f98b5ec44fafeb697b5cf9fdcda64a03422582ab03ee24c4",
+                "sha256:98922554e77f2e2c85a4f5d873a0f52efdc1b553f32444bd6c788b2ff583bf3e"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==0.4.0"
         },
         "requests": {
             "hashes": [
                 "sha256:63b52e3c866428a224f97cab011de738c36aec0185aa91cfacd418b5d58911d1",
                 "sha256:ec22d826a36ed72a7358ff3fe56cbd4ba69dd7a6718ffd450ff0e9df7a47ce6a"
             ],
-            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.19.1"
         },
         "requirementslib": {
             "hashes": [
-                "sha256:7288ec80fa62b78c6193eca85882605c4cdbb60361fc62478bd4a913c0b54400",
-                "sha256:8bb1b156d8b13337eab359273605b036d60735b350019addabb054e8a89a96f6"
+                "sha256:90151d8963f814e17190e067b60e92fb35fd1bc46c99f8dba3d7b0d93a3dd958",
+                "sha256:c3aeaa4e0b80843ba65a68878293e07ea52a8d0706dbba86b02dad6cd20ef2dd"
             ],
             "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
-            "version": "==1.1.5"
+            "version": "==1.1.6"
         },
         "resolvelib": {
             "hashes": [
-                "sha256:d52f2c0762deeb2a4cc34a84371a7a5ac85e111bdc69ce9ae729d8d636606ad6",
-                "sha256:eb759d43bbf50de9bf36afb9f6c269fabf9ff49084dbfad4ba67252d134bf4b5"
+                "sha256:6c4c6690b0bdd78bcc002e1a5d1b6abbde58c694a6ea1838f165b20d2c943db7",
+                "sha256:8734e53271ef98f38a2c99324d5e7905bc00c97dc3fc5bb7d83c82a979e71c04"
             ],
             "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
-            "version": "==0.2.1"
+            "version": "==0.2.2"
         },
         "scandir": {
             "hashes": [
@@ -217,7 +248,7 @@
                 "sha256:c9009c527929f6e25604aec39b0a43c3f831d2947d89d6caaab22f057b7055c8",
                 "sha256:f5c71e29b4e2af7ccdc03a020c626ede51da471173b4a6ad1e904f2b2e04b4bd"
             ],
-            "markers": "python_version < '3.5' and python_version < '3.6' and python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3' or python_version < '3.5' and python_version < '3.6' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version < '3.5' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.9.0"
         },
         "six": {
@@ -225,7 +256,7 @@
                 "sha256:70e8a77beed4562e7f14fe23a786b54f6296e34344c23bc42f07b15018ff98e9",
                 "sha256:832dc0e10feb1aa2c68dcc57dbb658f1c7e65b9b61af69048abc87a2db00a0eb"
             ],
-            "markers": "python_version < '3.6' and python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3' or python_version < '3.6' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3' or python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3' or python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version < '3.5' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.11.0"
         },
         "toml": {
@@ -233,15 +264,16 @@
                 "sha256:380178cde50a6a79f9d2cf6f42a62a5174febe5eea4126fe4038785f1d888d42",
                 "sha256:a7901919d3e4f92ffba7ff40a9d697e35bbbc8a8049fe8da742f34c83606d957"
             ],
+            "markers": "python_version >= '3.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==0.9.6"
         },
         "tomlkit": {
             "hashes": [
-                "sha256:618b057b96b488bb858102bdb38dd9d451c0617667031e320efea2392a39bec4",
-                "sha256:6856b5395f7c509baad1911aa3940b3c2fb33f53aff968ed1596c393ccea98e5"
+                "sha256:8ab16e93162fc44d3ad83d2aa29a7140b8f7d996ae1790a73b9a7aed6fb504ac",
+                "sha256:ca181cee7aee805d455628f7c94eb8ae814763769a93e69157f250fe4ebe1926"
             ],
-            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
-            "version": "==0.4.3"
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==0.4.4"
         },
         "typing": {
             "hashes": [
@@ -249,7 +281,7 @@
                 "sha256:57dcf675a99b74d64dacf6fba08fb17cf7e3d5fdff53d4a30ea2a5e7e52543d4",
                 "sha256:a4c8473ce11a65999c8f59cb093e70686b6c84c98df58c1dae9b3b196089858a"
             ],
-            "markers": "python_version < '3.5' and python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3' or python_version < '3.5' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version < '3.5' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==3.6.6"
         },
         "urllib3": {
@@ -257,9 +289,17 @@
                 "sha256:a68ac5e15e76e7e5dd2b8f94007233e01effe3e50e8daddf69acfd81cb686baf",
                 "sha256:b5725a0bd4ba422ab0e66e89e030c806576753ea3ee08554382c14e685d117b5"
             ],
-            "markers": "python_version < '4' and python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version < '4' and python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.23"
         },
+        "virtualenv": {
+            "hashes": [
+                "sha256:2ce32cd126117ce2c539f0134eb89de91a8413a29baac49cbab3eb50e2026669",
+                "sha256:ca07b4c0b54e14a91af9f34d0919790b016923d157afda5efdde55c96718f752"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==16.0.0"
+        },
         "vistir": {
             "extras": [
                 "spinner"
@@ -268,7 +308,7 @@
                 "sha256:8a360ac20cbcc0863d6dbbe7a52e8b2c9ebf48abd6833c3813a82c70708244af",
                 "sha256:bc6e10284792485c10585536e6aede9e38996c841cc9d2a67238cd05742c2d0b"
             ],
-            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==0.1.6"
         },
         "wheel": {
@@ -276,8 +316,16 @@
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+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==0.31.1"
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+            "version": "==0.14.0"
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     "develop": {
@@ -286,7 +334,6 @@
                 "sha256:674bb3bab080f598371f4443c5008cbfeb1a5e622dd312395d2d82af2c54c456",
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@@ -302,23 +349,14 @@
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             "version": "==1.4.3"
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@@ -331,32 +369,38 @@
         },
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-            "version": "==18.1.0"
+            "markers": "python_version >= '3.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
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             "version": "==2.6.0"
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             "version": "==1.0.post1"
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@@ -367,11 +411,26 @@
             "markers": "python_version >= '3.6'",
             "version": "==18.6b4"
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@@ -379,23 +438,94 @@
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             "version": "==2018.8.24"
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@@ -439,7 +569,7 @@
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@@ -455,7 +585,6 @@
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@@ -465,7 +594,7 @@
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             "version": "==1.1.6"
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@@ -492,27 +621,39 @@
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             "version": "==1.0.2"
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@@ -522,13 +663,21 @@
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@@ -548,7 +697,7 @@
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@@ -567,6 +716,14 @@
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@@ -580,7 +737,6 @@
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@@ -588,7 +744,6 @@
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@@ -641,37 +796,42 @@
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@@ -691,32 +851,32 @@
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@@ -728,19 +888,19 @@
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@@ -764,7 +924,7 @@
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@@ -795,7 +953,6 @@
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@@ -803,15 +960,16 @@
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@@ -825,15 +983,14 @@
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@@ -841,7 +998,7 @@
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@@ -849,9 +1006,17 @@
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@@ -860,16 +1025,31 @@
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         "wheel": {
             "hashes": [
                 "sha256:0a2e54558a0628f2145d2fc822137e322412115173e8a2ddbe1c9024338ae83c",
                 "sha256:80044e51ec5bbf6c894ba0bc48d26a8c20a9ba629f4ca19ea26ecfcf87685f5f"
             ],
-            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3' or python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==0.31.1"
+        },
+        "yaspin": {
+            "hashes": [
+                "sha256:36fdccc5e0637b5baa8892fe2c3d927782df7d504e9020f40eb2c1502518aa5a",
+                "sha256:8e52bf8079a48e2a53f3dfeec9e04addb900c101d1591c85df69cf677d3237e7"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==0.14.0"
         }
     }
 }
diff --git a/docs/requirements.txt b/docs/requirements.txt
new file mode 100644
index 0000000..8213302
--- /dev/null
+++ b/docs/requirements.txt
@@ -0,0 +1,2 @@
+sphinx
+sphinx_rtd_theme
diff --git a/news/53.feature.rst b/news/53.feature.rst
new file mode 100644
index 0000000..2589034
--- /dev/null
+++ b/news/53.feature.rst
@@ -0,0 +1 @@
+Refactored and restructured the internals for improved organization and separation of concerns.
diff --git a/setup.cfg b/setup.cfg
index 98ea198..e6879b5 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -37,20 +37,27 @@ python_requires = >=2.7,!=3.0,!=3.1,!=3.2,!=3.3
 setup_requires = setuptools>=36.2.2
 install_requires =
     appdirs
+    cached-property
     distlib
+    installer
     packaging
+    packagebuilder
     pip-shims>=0.1.2
     plette[validation]>=0.2.2
     requests
     resolvelib>=0.2.1,!=1.0.0.dev0
+    backports.functools_lru_cache; python_version<='2.7'
     requirementslib>=1.1.1
     six
+    virtualenv
     vistir[spinner]>=0.1.4
 
 [options.extras_require]
 pack =
     invoke
     parver
+virtualenv =
+    mork
 tests =
     pytest-xdist
     pytest-timeout
diff --git a/src/passa/actions/__init__.py b/src/passa/actions/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/passa/actions/add.py b/src/passa/actions/add.py
new file mode 100644
index 0000000..6cfb3e2
--- /dev/null
+++ b/src/passa/actions/add.py
@@ -0,0 +1,57 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+import itertools
+import sys
+
+
+def add_packages(packages=[], editables=[], project=None, dev=False, sync=False, clean=False):
+    from passa.models.lockers import PinReuseLocker
+    from passa.operations.lock import lock
+
+    lines = list(itertools.chain(
+        packages,
+        ("-e {}".format(e) for e in editables),
+    ))
+
+    project = project
+    for line in lines:
+        try:
+            project.add_line_to_pipfile(line, develop=dev)
+        except (TypeError, ValueError) as e:
+            print("Cannot add {line!r} to Pipfile: {error}".format(
+                line=line, error=str(e),
+            ), file=sys.stderr)
+            return 2
+
+    prev_lockfile = project.lockfile
+
+    locker = PinReuseLocker(project)
+    success = lock(locker)
+    if not success:
+        return 1
+
+    project._p.write()
+    project._l.write()
+    print("Written to project at", project.root)
+
+    if not sync:
+        return
+
+    from installer.synchronizer import Synchronizer
+    from installer.operations import sync
+
+    lockfile_diff = project.difference_lockfile(prev_lockfile)
+    default = any(lockfile_diff.default)
+    develop = any(lockfile_diff.develop)
+
+    syncer = Synchronizer(
+        project, default=default, develop=develop,
+        clean_unneeded=clean
+    )
+    success = sync(syncer)
+    if not success:
+        return 1
+
+    print("Synchronized project at", project.root)
diff --git a/src/passa/actions/clean.py b/src/passa/actions/clean.py
new file mode 100644
index 0000000..d4b8193
--- /dev/null
+++ b/src/passa/actions/clean.py
@@ -0,0 +1,17 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+
+def clean(project, default=True, dev=False, sync=True):
+    from installer.synchronizer import Cleaner
+    from installer.operations import clean
+
+    cleaner = Cleaner(project, default=default, develop=dev, sync=sync)
+
+    success = clean(cleaner)
+    if not success:
+        return 1
+
+    if sync:
+        print("Cleaned project at", project.root)
diff --git a/src/passa/actions/freeze.py b/src/passa/actions/freeze.py
new file mode 100644
index 0000000..ca4dbb2
--- /dev/null
+++ b/src/passa/actions/freeze.py
@@ -0,0 +1,93 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+import contextlib
+import io
+import itertools
+import sys
+
+import vistir.misc
+
+
+def _source_as_lines(source, extra):
+    url = source["url"]
+    if extra:
+        lines = ["--extra-index-url {}".format(url)]
+    else:
+        lines = ["--index-url {}".format(url)]
+    if not source.get("verify_ssl", True):
+        lines = ["--trusted-host {}".format(url)]
+    return lines
+
+
+def _requirement_as_line(requirement, sources, include_hashes):
+    if requirement.index:
+        sources = sources
+    else:
+        sources = None
+    line = vistir.misc.to_text(
+        requirement.as_line(sources=sources, include_hashes=include_hashes)
+    )
+    return line
+
+
+@contextlib.contextmanager
+def open_for_output(filename):
+    if filename is None:
+        yield sys.stdout
+        return
+    with io.open(filename, "w", encoding="utf-8", newline="\n") as f:
+        yield f
+
+
+def freeze(project=None, default=True, dev=True, include_hashes=None, target=None):
+    from requirementslib import Requirement
+
+    lockfile = project.lockfile
+    if not lockfile:
+        print("Pipfile.lock is required to export.", file=sys.stderr)
+        return 1
+
+    section_names = []
+    if default:
+        section_names.append("default")
+    if dev:
+        section_names.append("develop")
+    requirements = [
+        Requirement.from_pipfile(key, entry._data)
+        for key, entry in itertools.chain.from_iterable(
+            lockfile.get(name, {}).items()
+            for name in section_names
+        )
+    ]
+
+    if include_hashes is None:
+        include_hashes = all(r.is_named for r in requirements)
+
+    sources = lockfile.meta.sources._data
+
+    source_lines = list(vistir.misc.dedup(itertools.chain(
+        itertools.chain.from_iterable(
+            _source_as_lines(source, False)
+            for source in sources[:1]
+        ),
+        itertools.chain.from_iterable(
+            _source_as_lines(source, True)
+            for source in sources[1:]
+        ),
+    )))
+
+    requirement_lines = sorted(vistir.misc.dedup(
+        _requirement_as_line(requirement, sources, include_hashes)
+        for requirement in requirements
+    ))
+
+    with open_for_output(target) as f:
+        for line in source_lines:
+            f.write(line)
+            f.write("\n")
+        f.write("\n")
+        for line in requirement_lines:
+            f.write(line)
+            f.write("\n")
diff --git a/src/passa/actions/init.py b/src/passa/actions/init.py
new file mode 100644
index 0000000..baf8445
--- /dev/null
+++ b/src/passa/actions/init.py
@@ -0,0 +1,54 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+import io
+import os
+
+import six
+
+import packagebuilder
+
+import plette
+import vistir
+
+
+def get_sources(urls, trusted_hosts):
+    trusted_hosts = [six.moves.urllib.parse.urlparse(url).netloc for url in trusted_hosts]
+    sources = []
+    for url in urls:
+        parsed_url = six.moves.urllib.parse.urlparse(url)
+        netloc = parsed_url.netloc
+        if '@' in netloc:
+            _, _, netloc = netloc.rpartition('@')
+        name, _, _ = netloc.partition('.')  # Just use the domain name as the source name
+        verify_ssl = True
+        if netloc in trusted_hosts:
+            verify_ssl = False
+        sources.append({"url": url, "name": name, "verify_ssl": verify_ssl})
+    return sources
+
+
+def init_project(root=None, python_version=None):
+    pipfile_path = os.path.join(root, "Pipfile")
+    if os.path.isfile(pipfile_path):
+        raise RuntimeError("{0!r} is already a Pipfile project".format(root))
+    if not os.path.exists(root):
+        vistir.path.mkdir_p(root, mode=0o755)
+    sources = packagebuilder.get_sources()
+    data = {
+        "source": sources,
+        "packages": {},
+        "dev-packages": {},
+    }
+    if python_version:
+        data["requires"] = {"python_version": python_version}
+    return create_project(pipfile_path=pipfile_path, data=data)
+
+
+def create_project(pipfile_path, data={}):
+    pipfile = plette.pipfiles.Pipfile(data=data)
+    with io.open(pipfile_path, "w") as fh:
+        pipfile.dump(fh)
+    print("Successfully created new pipfile at {0!r}".format(pipfile_path))
+    return 0
diff --git a/src/passa/actions/install.py b/src/passa/actions/install.py
new file mode 100644
index 0000000..c920906
--- /dev/null
+++ b/src/passa/actions/install.py
@@ -0,0 +1,32 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+
+def install(project=None, check=True, dev=False, clean=True):
+    from passa.models.lockers import BasicLocker
+    from passa.operations.lock import lock
+
+    project = project
+
+    if not check or not project.is_synced():
+        locker = BasicLocker(project)
+        success = lock(locker)
+        if not success:
+            return 1
+        project._l.write()
+        print("Written to project at", project.root)
+
+    from installer.synchronizer import Synchronizer
+    from installer.operations import sync
+
+    syncer = Synchronizer(
+        project, default=True, develop=dev,
+        clean_unneeded=clean,
+    )
+
+    success = sync(syncer)
+    if not success:
+        return 1
+
+    print("Synchronized project at", project.root)
diff --git a/src/passa/actions/lock.py b/src/passa/actions/lock.py
new file mode 100644
index 0000000..7c09469
--- /dev/null
+++ b/src/passa/actions/lock.py
@@ -0,0 +1,17 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+
+def lock(project=None):
+    from passa.models.lockers import BasicLocker
+    from passa.operations.lock import lock
+
+    project = project
+    locker = BasicLocker(project)
+    success = lock(locker)
+    if not success:
+        return
+
+    project._l.write()
+    print("Written to project at", project.root)
diff --git a/src/passa/actions/remove.py b/src/passa/actions/remove.py
new file mode 100644
index 0000000..2fcba75
--- /dev/null
+++ b/src/passa/actions/remove.py
@@ -0,0 +1,38 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+
+def remove(project=None, only="default", packages=[], clean=True, sync=False):
+    from passa.models.lockers import PinReuseLocker
+    from passa.operations.lock import lock
+
+    default = (only != "dev")
+    develop = (only != "default")
+
+    project = project
+    project.remove_keys_from_pipfile(
+        packages, default=default, develop=develop,
+    )
+
+    locker = PinReuseLocker(project)
+    success = lock(locker)
+    if not success:
+        return 1
+
+    project._p.write()
+    project._l.write()
+    print("Written to project at", project.root)
+
+    if not clean:
+        return
+
+    from installer.synchronizer import Cleaner
+    from installer.operations import clean
+
+    cleaner = Cleaner(project, default=True, develop=True)
+    success = clean(cleaner)
+    if not success:
+        return 1
+
+    print("Cleaned project at", project.root)
diff --git a/src/passa/actions/sync.py b/src/passa/actions/sync.py
new file mode 100644
index 0000000..e785627
--- /dev/null
+++ b/src/passa/actions/sync.py
@@ -0,0 +1,20 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+
+def sync(project=None, dev=False, clean=True):
+    from installer.synchronizers import Synchronizer
+    from installer.operations import sync
+
+    project = project
+    syncer = Synchronizer(
+        project, default=True, develop=dev,
+        clean_unneeded=clean,
+    )
+
+    success = sync(syncer)
+    if not success:
+        return 1
+
+    print("Synchronized project at", project.root)
diff --git a/src/passa/actions/upgrade.py b/src/passa/actions/upgrade.py
new file mode 100644
index 0000000..7fd3c1e
--- /dev/null
+++ b/src/passa/actions/upgrade.py
@@ -0,0 +1,52 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+import sys
+
+
+def upgrade(project=None, strategy="only-if-needed", sync=True, packages=[]):
+    from passa.models.lockers import EagerUpgradeLocker, PinReuseLocker
+    from passa.operations.lock import lock
+
+    for package in packages:
+        if not project.contains_key_in_pipfile(package):
+            print("{package!r} not found in Pipfile".format(
+                package=package,
+            ), file=sys.stderr)
+            return 2
+
+    project.remove_keys_from_lockfile(packages)
+
+    prev_lockfile = project.lockfile
+
+    if strategy == "eager":
+        locker = EagerUpgradeLocker(project, packages)
+    else:
+        locker = PinReuseLocker(project)
+    success = lock(locker)
+    if not success:
+        return 1
+
+    project._l.write()
+    print("Written to project at", project.root)
+
+    if not sync:
+        return
+
+    from installer.operations import sync
+    from installer.synchronizer import Synchronizer
+
+    lockfile_diff = project.difference_lockfile(prev_lockfile)
+    default = bool(any(lockfile_diff.default))
+    develop = bool(any(lockfile_diff.develop))
+
+    syncer = Synchronizer(
+        project, default=default, develop=develop,
+        clean_unneeded=False,
+    )
+    success = sync(syncer)
+    if not success:
+        return 1
+
+    print("Synchronized project at", project.root)
diff --git a/src/passa/cli/__init__.py b/src/passa/cli/__init__.py
index cb503e8..b6891d3 100644
--- a/src/passa/cli/__init__.py
+++ b/src/passa/cli/__init__.py
@@ -34,7 +34,7 @@ def main(argv=None):
             continue
         parser = subparsers.add_parser(klass.name, help=klass.description)
         command = klass(parser)
-        parser.set_defaults(func=command.main)
+        parser.set_defaults(func=command.run)
 
     options = root_parser.parse_args(argv)
 
diff --git a/src/passa/cli/_base.py b/src/passa/cli/_base.py
index 68e0e34..0ca4868 100644
--- a/src/passa/cli/_base.py
+++ b/src/passa/cli/_base.py
@@ -6,31 +6,7 @@
 import os
 import sys
 
-import tomlkit.exceptions
-
-
-def build_project(root):
-    # This is imported lazily to reduce import overhead. Not evey command
-    # needs the project instance.
-    from passa.internals.projects import Project
-    root = os.path.abspath(root)
-    if not os.path.isfile(os.path.join(root, "Pipfile")):
-        raise argparse.ArgumentError(
-            "{0!r} is not a Pipfile project".format(root),
-        )
-    try:
-        project = Project(root)
-    except tomlkit.exceptions.ParseError as e:
-        raise argparse.ArgumentError(
-            "failed to parse Pipfile: {0!r}".format(str(e)),
-        )
-    return project
-
-
-# Better error reporting. Recent argparse would emit something like
-# "invalid project root value: 'xxxxxx'". The str() wrapper is needed to
-# keep Python 2 happy :(
-build_project.__name__ = str("project root")
+from .options import project
 
 
 class BaseCommand(object):
@@ -38,19 +14,30 @@ class BaseCommand(object):
     """
     name = None
     description = None
-    parsed_main = None
-
-    def __init__(self, parser):
+    default_arguments = [project]
+    arguments = []
+
+    def __init__(self, parser=None):
+        if not parser:
+            parser = argparse.ArgumentParser(
+                prog=os.path.basename(sys.argv[0]),
+                description="Base argument parser for passa"
+            )
         self.parser = parser
         self.add_arguments()
 
     @classmethod
-    def run_current_module(cls):
+    def build_parser(cls):
         parser = argparse.ArgumentParser(
             prog="passa {}".format(cls.name),
             description=cls.description,
         )
-        cls(parser)()
+        return cls(parser)
+
+    @classmethod
+    def run_parser(cls):
+        parser = cls.build_parser()
+        parser()
 
     def __call__(self, argv=None):
         options = self.parser.parse_args(argv)
@@ -58,16 +45,17 @@ def __call__(self, argv=None):
         if result is not None:
             sys.exit(result)
 
+    def add_default_arguments(self):
+        for arg in self.default_arguments:
+            arg.add_to_parser(self.parser)
+
     def add_arguments(self):
-        self.parser.add_argument(
-            "--project",
-            metavar="project",
-            default=os.getcwd(),
-            type=build_project,
-            help="path to project root (directory containing Pipfile)",
-        )
+        self.add_default_arguments()
+        for arg in self.arguments:
+            arg.add_to_parser(self.parser)
 
     def main(self, options):
-        # This __dict__ access is needed for Python 2 to prevent Python from
-        # wrapping parsed_main into an unbounded method.
-        return type(self).__dict__["parsed_main"](options)
+        return self.run(options)
+
+    def run(self, options):
+        raise NotImplementedError
diff --git a/src/passa/cli/add.py b/src/passa/cli/add.py
index 26ce0ed..2635b98 100644
--- a/src/passa/cli/add.py
+++ b/src/passa/cli/add.py
@@ -2,98 +2,28 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
-import itertools
-import sys
-
+from ..actions.add import add_packages
 from ._base import BaseCommand
-
-
-def main(options):
-    from passa.internals.lockers import PinReuseLocker
-    from passa.operations.lock import lock
-
-    lines = list(itertools.chain(
-        options.requirement_lines,
-        ("-e {}".format(e) for e in options.editable_lines),
-    ))
-
-    project = options.project
-    for line in lines:
-        try:
-            project.add_line_to_pipfile(line, develop=options.dev)
-        except (TypeError, ValueError) as e:
-            print("Cannot add {line!r} to Pipfile: {error}".format(
-                line=line, error=str(e),
-            ), file=sys.stderr)
-            return 2
-
-    prev_lockfile = project.lockfile
-
-    locker = PinReuseLocker(project)
-    success = lock(locker)
-    if not success:
-        return 1
-
-    project._p.write()
-    project._l.write()
-    print("Written to project at", project.root)
-
-    if not options.sync:
-        return
-
-    from passa.internals.synchronizers import Synchronizer
-    from passa.operations.sync import sync
-
-    lockfile_diff = project.difference_lockfile(prev_lockfile)
-    default = bool(any(lockfile_diff.default))
-    develop = bool(any(lockfile_diff.develop))
-
-    syncer = Synchronizer(
-        project, default=default, develop=develop,
-        clean_unneeded=False,
-    )
-    success = sync(syncer)
-    if not success:
-        return 1
-
-    print("Synchronized project at", project.root)
+from .options import package_group, clean_group
 
 
 class Command(BaseCommand):
 
     name = "add"
     description = "Add packages to project."
-    parsed_main = main
+    arguments = [package_group, clean_group]
 
-    def add_arguments(self):
-        super(Command, self).add_arguments()
-        self.parser.add_argument(
-            "requirement_lines", metavar="requirement",
-            nargs="*",
-            help="requirement to add (can be used multiple times)",
-        )
-        self.parser.add_argument(
-            "-e", "--editable",
-            metavar="requirement", dest="editable_lines",
-            action="append", default=[],
-            help="editable requirement to add (can be used multiple times)",
-        )
-        self.parser.add_argument(
-            "--dev",
-            action="store_true",
-            help="add packages to [dev-packages]",
-        )
-        self.parser.add_argument(
-            "--no-sync", dest="sync",
-            action="store_false", default=True,
-            help="do not synchronize the environment",
-        )
-
-    def main(self, options):
-        if not options.editable_lines and not options.requirement_lines:
+    def run(self, options):
+        if not options.editables and not options.packages:
             self.parser.error("Must supply either a requirement or --editable")
-        return super(Command, self).main(options)
+        return add_packages(
+            packages=options.packages,
+            editables=options.editables,
+            project=options.project,
+            dev=options.dev,
+            clean=options.clean
+        )
 
 
 if __name__ == "__main__":
-    Command.run_current_module()
+    Command.run_parser()
diff --git a/src/passa/cli/clean.py b/src/passa/cli/clean.py
index cd1b679..a74d814 100644
--- a/src/passa/cli/clean.py
+++ b/src/passa/cli/clean.py
@@ -2,37 +2,23 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
+from ..actions.clean import clean
 from ._base import BaseCommand
-
-
-def main(options):
-    from passa.internals.synchronizers import Cleaner
-    from passa.operations.sync import clean
-
-    project = options.project
-    cleaner = Cleaner(project, default=True, develop=options.dev)
-
-    success = clean(cleaner)
-    if not success:
-        return 1
-
-    print("Cleaned project at", project.root)
+from .options import dev, no_default, sync_group
 
 
 class Command(BaseCommand):
 
     name = "clean"
     description = "Uninstall unlisted packages from the environment."
-    parsed_main = main
-
-    def add_arguments(self):
-        super(Command, self).add_arguments()
-        self.parser.add_argument(
-            "--no-dev", dest="dev",
-            action="store_false", default=True,
-            help="uninstall develop packages, only keep default ones",
+    arguments = [dev, no_default, sync_group]
+
+    def run(self, options):
+        return clean(
+            project=options.project, default=options.default, dev=options.dev,
+            sync=options.sync
         )
 
 
 if __name__ == "__main__":
-    Command.run_current_module()
+    Command.run_parser()
diff --git a/src/passa/cli/freeze.py b/src/passa/cli/freeze.py
index 6ca5717..053c727 100644
--- a/src/passa/cli/freeze.py
+++ b/src/passa/cli/freeze.py
@@ -2,137 +2,23 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
-import contextlib
-import io
-import itertools
-import sys
-
-import six
-import vistir.misc
-
+from ..actions.freeze import freeze
 from ._base import BaseCommand
-
-
-def _source_as_lines(source, extra):
-    url = source["url"]
-    if extra:
-        lines = ["--extra-index-url {}".format(url)]
-    else:
-        lines = ["--index-url {}".format(url)]
-    if not source.get("verify_ssl", True):
-        lines = ["--trusted-host {}".format(url)]
-    return lines
-
-
-def _requirement_as_line(requirement, sources, include_hashes):
-    if requirement.index:
-        sources = sources
-    else:
-        sources = None
-    line = requirement.as_line(sources=sources, include_hashes=include_hashes)
-    if not isinstance(line, six.text_type):
-        line = line.decode("utf-8")
-    return line
-
-
-@contextlib.contextmanager
-def open_for_output(filename):
-    if filename is None:
-        yield sys.stdout
-        return
-    with io.open(filename, "w", encoding="utf-8", newline="\n") as f:
-        yield f
-
-
-def main(options):
-    from requirementslib import Requirement
-
-    lockfile = options.project.lockfile
-    if not lockfile:
-        print("Pipfile.lock is required to export.", file=sys.stderr)
-        return 1
-
-    section_names = []
-    if options.default:
-        section_names.append("default")
-    if options.dev:
-        section_names.append("develop")
-    requirements = [
-        Requirement.from_pipfile(key, entry._data)
-        for key, entry in itertools.chain.from_iterable(
-            lockfile.get(name, {}).items()
-            for name in section_names
-        )
-    ]
-
-    include_hashes = options.include_hashes
-    if include_hashes is None:
-        include_hashes = all(r.is_named for r in requirements)
-
-    sources = lockfile.meta.sources._data
-
-    source_lines = list(vistir.misc.dedup(itertools.chain(
-        itertools.chain.from_iterable(
-            _source_as_lines(source, False)
-            for source in sources[:1]
-        ),
-        itertools.chain.from_iterable(
-            _source_as_lines(source, True)
-            for source in sources[1:]
-        ),
-    )))
-
-    requirement_lines = sorted(vistir.misc.dedup(
-        _requirement_as_line(requirement, sources, include_hashes)
-        for requirement in requirements
-    ))
-
-    with open_for_output(options.target) as f:
-        for line in source_lines:
-            f.write(line)
-            f.write("\n")
-        f.write("\n")
-        for line in requirement_lines:
-            f.write(line)
-            f.write("\n\n")
+from .options import dev, include_hashes_group, no_default, target
 
 
 class Command(BaseCommand):
 
     name = "freeze"
     description = "Export project depenencies to requirements.txt."
-    parsed_main = main
+    arguments = [dev, no_default, target, include_hashes_group]
 
-    def add_arguments(self):
-        super(Command, self).add_arguments()
-        self.parser.add_argument(
-            "--target",
-            default=None,
-            help="file to export into (default is to print to stdout)",
-        )
-        self.parser.add_argument(
-            "--dev",
-            action="store_true", default=False,
-            help="include development packages in requirements.txt",
-        )
-        self.parser.add_argument(
-            "--no-default", dest="default",
-            action="store_false", default=True,
-            help="do not include default packages in requirements.txt",
-        )
-        include_hashes_group = self.parser.add_mutually_exclusive_group()
-        include_hashes_group.add_argument(
-            "--include-hashes", dest="include_hashes",
-            action="store_true",
-            help="output hashes in requirements.txt (default is to guess)",
-        )
-        include_hashes_group.add_argument(
-            "--no-include-hashes", dest="include_hashes",
-            action="store_false",
-            help=("do not output hashes in requirements.txt "
-                  "(default is to guess)"),
+    def run(self, options):
+        return freeze(
+            project=options.project, default=options.default, dev=options.dev,
+            include_hashes=options.include_hashes
         )
 
 
 if __name__ == "__main__":
-    Command.run_current_module()
+    Command.run_parser()
diff --git a/src/passa/cli/init.py b/src/passa/cli/init.py
new file mode 100644
index 0000000..95ce8d8
--- /dev/null
+++ b/src/passa/cli/init.py
@@ -0,0 +1,32 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+import argparse
+import os
+
+from ..actions.init import init_project
+from ._base import BaseCommand
+from .options import new_project_group
+
+
+class Command(BaseCommand):
+
+    name = "init"
+    description = "Create a new project."
+    default_arguments = []
+    arguments = [new_project_group]
+
+    def run(self, options):
+        pipfile_path = os.path.join(options.project, "Pipfile")
+        if os.path.exists(pipfile_path):
+            raise argparse.ArgumentError(
+                "{0!r} is already a Pipfile project".format(options.project),
+            )
+        return init_project(
+            root=options.project, python_version=options.python_version
+        )
+
+
+if __name__ == "__main__":
+    Command.run_parser()
diff --git a/src/passa/cli/install.py b/src/passa/cli/install.py
index f47377b..1c0b459 100644
--- a/src/passa/cli/install.py
+++ b/src/passa/cli/install.py
@@ -2,62 +2,21 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
+from ..actions.install import install
 from ._base import BaseCommand
-
-
-def main(options):
-    from passa.internals.lockers import BasicLocker
-    from passa.operations.lock import lock
-
-    project = options.project
-
-    if not options.check or not project.is_synced():
-        locker = BasicLocker(project)
-        success = lock(locker)
-        if not success:
-            return 1
-        project._l.write()
-        print("Written to project at", project.root)
-
-    from passa.internals.synchronizers import Synchronizer
-    from passa.operations.sync import sync
-
-    syncer = Synchronizer(
-        project, default=True, develop=options.dev,
-        clean_unneeded=options.clean,
-    )
-
-    success = sync(syncer)
-    if not success:
-        return 1
-
-    print("Synchronized project at", project.root)
+from .options import dev, no_check, no_clean
 
 
 class Command(BaseCommand):
 
     name = "install"
     description = "Generate Pipfile.lock to synchronize the environment."
-    parsed_main = main
-
-    def add_arguments(self):
-        super(Command, self).add_arguments()
-        self.parser.add_argument(
-            "--no-check", dest="check",
-            action="store_false", default=True,
-            help="do not check if Pipfile.lock is update, always resolve",
-        )
-        self.parser.add_argument(
-            "--dev",
-            action="store_true",
-            help="install develop packages",
-        )
-        self.parser.add_argument(
-            "--no-clean", dest="clean",
-            action="store_false", default=True,
-            help="do not uninstall packages not specified in Pipfile.lock",
-        )
+    arguments = [no_check, dev, no_clean]
+
+    def run(self, options):
+        return install(project=options.project, check=options.check, dev=options.dev,
+                            clean=options.clean)
 
 
 if __name__ == "__main__":
-    Command.run_current_module()
+    Command.run_parser()
diff --git a/src/passa/cli/lock.py b/src/passa/cli/lock.py
index 67b1d11..9b0651a 100644
--- a/src/passa/cli/lock.py
+++ b/src/passa/cli/lock.py
@@ -2,28 +2,17 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
+from ..actions.lock import lock
 from ._base import BaseCommand
 
 
-def main(options):
-    from passa.internals.lockers import BasicLocker
-    from passa.operations.lock import lock
-
-    project = options.project
-    locker = BasicLocker(project)
-    success = lock(locker)
-    if not success:
-        return
-
-    project._l.write()
-    print("Written to project at", project.root)
-
-
 class Command(BaseCommand):
     name = "lock"
     description = "Generate Pipfile.lock."
-    parsed_main = main
+
+    def run(self, options):
+        return lock(project=options.project)
 
 
 if __name__ == "__main__":
-    Command.run_current_module()
+    Command.run_parser()
diff --git a/src/passa/cli/options.py b/src/passa/cli/options.py
new file mode 100644
index 0000000..d2a6378
--- /dev/null
+++ b/src/passa/cli/options.py
@@ -0,0 +1,206 @@
+# -*- coding=utf-8 -*-
+from __future__ import absolute_import
+
+import argparse
+import inspect
+import os
+import sys
+
+import six
+import tomlkit.exceptions
+
+import passa.models.projects
+import vistir
+
+
+PYTHON_VERSION = ".".join(str(v) for v in sys.version_info[:2])
+
+
+class Project(passa.models.projects.Project):
+    def __init__(self, root, *args, **kwargs):
+        root = vistir.compat.Path(root).absolute()
+        pipfile = root.joinpath("Pipfile")
+        if not pipfile.is_file():
+            raise argparse.ArgumentError(
+                project, "{0!r} is not a Pipfile project".format(root.as_posix()),
+            )
+        try:
+            super(Project, self).__init__(root.as_posix(), *args, **kwargs)
+        except tomlkit.exceptions.ParseError as e:
+            raise argparse.ArgumentError(
+                project, "failed to parse Pipfile: {0!r}".format(str(e)),
+            )
+
+    def __name__(self):
+        return "Project Root"
+
+
+class OptionMeta(type):
+
+    @property
+    def action_map(self):
+        action_map = getattr(self, '_action_map', None)
+        if not action_map:
+            self.action_map = {
+                name.strip("_").replace("Action", ""): obj
+                for name, obj in inspect.getmembers(argparse)
+                if name.startswith('_') and name.endswith('Action')
+            }
+        return self._action_map
+
+    @action_map.setter
+    def action_map(self, action_map):
+        self._action_map = action_map
+
+
+@six.add_metaclass(OptionMeta)
+class Option(object):
+    def __init__(self, *args, **kwargs):
+        self.args = list(args)
+        self.kwargs = kwargs.copy()
+        if "dest" not in kwargs and not args[0].startswith("-"):
+            dest = list(args).pop(0)
+        else:
+            dest = kwargs.pop("dest", args[0].lstrip("-").replace("-", "_"))
+        action = kwargs.pop("action", None)
+        if not action:
+            if 'const' in kwargs:
+                action = 'store_const'
+            else:
+                action = 'store'
+        self.action = self.get_option(action, args, dest, **kwargs)
+
+    @classmethod
+    def get_option(cls, action, option_strings, dest, *args, **kwargs):
+        if action:
+            action = action.title().replace("_", "")
+            return cls.action_map[action](list(option_strings), dest, *args, **kwargs)
+        return
+
+    def add_to_parser(self, parser):
+        parser.add_argument(*self.args, **self.kwargs)
+
+    def add_to_group(self, group):
+        group.add_argument(*self.args, **self.kwargs)
+
+
+class ArgumentGroup(object):
+    def __init__(self, name, parser=None, is_mutually_exclusive=False, required=False, options=[]):
+        self.name = name
+        self.options = options
+        self.parser = parser
+        self.required = required
+        self.is_mutually_exclusive = is_mutually_exclusive
+        self.argument_group = None
+
+    def add_to_parser(self, parser):
+        group = None
+        if self.is_mutually_exclusive:
+            group = parser.add_mutually_exclusive_group(required=self.required)
+        else:
+            group = parser.add_argument_group()
+        for option in self.options:
+            option.add_to_group(group)
+        self.argument_group = group
+        self.parser = parser
+
+    def add_to_group(self, group):
+        self.add_to_parser(group)
+
+
+project = Option(
+    "--project", metavar="project", default=os.getcwd(), type=Project,
+    help="path to project root (directory containing Pipfile)",
+)
+
+new_project = Option(
+    "--project", metavar="project", default=os.getcwd(), type=str,
+    help="path to project root (directory containing Pipfile)",
+)
+
+python_version = Option(
+    "--py-version", "--python-version", "--requires-python", metavar="python_version",
+    dest="python_version", default=PYTHON_VERSION, type=str,
+    help="required minor python version for the project"
+)
+
+packages = Option(
+    "packages", metavar="package", nargs="*",
+    help="requirement to add (can be used multiple times)",
+)
+
+editable = Option(
+    '-e', '--editable', dest='editables', nargs="*", default=[], metavar='path/vcs',
+    help="editable requirement to add (can be used multiple times)",
+)
+
+dev = Option(
+    "--dev", action="store_true", default=False,
+    help="Use [dev-packages] for install/freeze/uninstall operations",
+)
+
+no_sync = Option(
+    "--no-sync", dest="sync", action="store_false", default=True,
+    help="do not synchronize the environment",
+)
+
+sync = Option(
+    "--sync", dest="sync", action="store_true", help="synchronize the environment",
+    default=False
+)
+
+target = Option(
+    "-t", "--target", default=None,
+    help="file to export into (default is to print to stdout)"
+)
+
+no_default = Option(
+    "--no-default", dest="default", action="store_false", default=True,
+    help="do not include default packages when exporting, importing, or cleaning"
+)
+
+include_hashes = Option(
+    "--include-hashes", dest="include_hashes", action="store_true",
+    help="output hashes in requirements.txt (default is to guess)",
+)
+
+no_include_hashes = Option(
+    "--no-include-hashes", dest="include_hashes", action="store_false",
+    help="do not output hashes in requirements.txt (default is to guess)",
+)
+
+no_check = Option(
+    "--no-check", dest="check", action="store_false", default=True,
+    help="do not check if Pipfile.lock is up to date, always resolve",
+)
+
+no_clean = Option(
+    "--no-clean", dest="clean", action="store_false", default=True,
+    help="do not remove packages not specified in Pipfile.lock",
+)
+
+clean = Option(
+    "--clean", dest="clean", action="store_true", default=False,
+    help="remove packages not specified in Pipfile.lock",
+)
+dev_only = Option(
+    "--dev", dest="only", action="store_const", const="dev",
+    help="only try to modify [dev-packages]",
+)
+
+default_only = Option(
+    "--default", dest="only", action="store_const", const="default",
+    help="only try to modify [default]",
+)
+
+strategy = Option(
+    "--strategy", choices=["eager", "only-if-needed"], default="only-if-needed",
+    help="how dependency upgrading is handled",
+)
+
+include_hashes_group = ArgumentGroup("include_hashes", is_mutually_exclusive=True, options=[include_hashes, no_include_hashes])
+dev_group = ArgumentGroup("dev", is_mutually_exclusive="True", options=[dev_only, default_only])
+new_project_group = ArgumentGroup("new-project", options=[new_project, python_version])
+clean_group = ArgumentGroup("clean", is_mutually_exclusive=True, options=[clean, no_clean])
+sync_group = ArgumentGroup("sync", is_mutually_exclusive=True, options=[sync, no_sync])
+package_group = ArgumentGroup("packages", options=[packages, editable, dev, sync_group])
diff --git a/src/passa/cli/remove.py b/src/passa/cli/remove.py
index b1dbfd7..041c195 100644
--- a/src/passa/cli/remove.py
+++ b/src/passa/cli/remove.py
@@ -2,74 +2,21 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
+from ..actions.remove import remove
 from ._base import BaseCommand
-
-
-def main(options):
-    from passa.internals.lockers import PinReuseLocker
-    from passa.operations.lock import lock
-
-    default = (options.only != "dev")
-    develop = (options.only != "default")
-
-    project = options.project
-    project.remove_keys_from_pipfile(
-        options.packages, default=default, develop=develop,
-    )
-
-    locker = PinReuseLocker(project)
-    success = lock(locker)
-    if not success:
-        return 1
-
-    project._p.write()
-    project._l.write()
-    print("Written to project at", project.root)
-
-    if not options.clean:
-        return
-
-    from passa.internals.synchronizers import Cleaner
-    from passa.operations.sync import clean
-
-    cleaner = Cleaner(project, default=True, develop=True)
-    success = clean(cleaner)
-    if not success:
-        return 1
-
-    print("Cleaned project at", project.root)
+from .options import dev_group, clean_group, sync_group, packages
 
 
 class Command(BaseCommand):
 
     name = "remove"
     description = "Remove packages from project."
-    parsed_main = main
+    arguments = [dev_group, clean_group, sync_group, packages]
 
-    def add_arguments(self):
-        super(Command, self).add_arguments()
-        self.parser.add_argument(
-            "packages", metavar="package",
-            nargs="+",
-            help="package to remove (can be used multiple times)",
-        )
-        dev_group = self.parser.add_mutually_exclusive_group()
-        dev_group.add_argument(
-            "--dev", dest="only",
-            action="store_const", const="dev",
-            help="only try to remove from [dev-packages]",
-        )
-        dev_group.add_argument(
-            "--default", dest="only",
-            action="store_const", const="default",
-            help="only try to remove from [packages]",
-        )
-        self.parser.add_argument(
-            "--no-clean", dest="clean",
-            action="store_false", default=True,
-            help="do not uninstall packages not specified in Pipfile.lock",
-        )
+    def run(self, options):
+        return remove(project=options.project, only=options.only,
+                        packages=options.packages, clean=options.clean, sync=options.sync)
 
 
 if __name__ == "__main__":
-    Command.run_current_module()
+    Command.run_parser()
diff --git a/src/passa/cli/sync.py b/src/passa/cli/sync.py
index ade81e0..9a31fe1 100644
--- a/src/passa/cli/sync.py
+++ b/src/passa/cli/sync.py
@@ -2,45 +2,20 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
+from ..actions.sync import sync
 from ._base import BaseCommand
-
-
-def main(options):
-    from passa.internals.synchronizers import Synchronizer
-    from passa.operations.sync import sync
-
-    project = options.project
-    syncer = Synchronizer(
-        project, default=True, develop=options.dev,
-        clean_unneeded=options.clean,
-    )
-
-    success = sync(syncer)
-    if not success:
-        return 1
-
-    print("Synchronized project at", project.root)
+from .options import dev, clean_group
 
 
 class Command(BaseCommand):
 
     name = "sync"
     description = "Install Pipfile.lock into the environment."
-    parsed_main = main
-
-    def add_arguments(self):
-        super(Command, self).add_arguments()
-        self.parser.add_argument(
-            "--dev",
-            action="store_true",
-            help="install develop packages",
-        )
-        self.parser.add_argument(
-            "--no-clean", dest="clean",
-            action="store_false", default=True,
-            help="do not uninstall packages not specified in Pipfile.lock",
-        )
+    arguments = [dev, clean_group]
+
+    def run(self, options):
+        return sync(project=options.project, dev=options.dev, clean=options.clean)
 
 
 if __name__ == "__main__":
-    Command.run_current_module()
+    Command.run_parser()
diff --git a/src/passa/cli/upgrade.py b/src/passa/cli/upgrade.py
index 011fff6..c7696c2 100644
--- a/src/passa/cli/upgrade.py
+++ b/src/passa/cli/upgrade.py
@@ -1,91 +1,21 @@
 # -*- coding=utf-8 -*-
-
 from __future__ import absolute_import, print_function, unicode_literals
 
-import sys
-
+from ..actions.upgrade import upgrade
 from ._base import BaseCommand
-
-
-def main(options):
-    from passa.internals.lockers import EagerUpgradeLocker, PinReuseLocker
-    from passa.operations.lock import lock
-
-    project = options.project
-    packages = options.packages
-    for package in packages:
-        if not project.contains_key_in_pipfile(package):
-            print("{package!r} not found in Pipfile".format(
-                package=package,
-            ), file=sys.stderr)
-            return 2
-
-    project.remove_keys_from_lockfile(packages)
-
-    prev_lockfile = project.lockfile
-
-    if options.strategy == "eager":
-        locker = EagerUpgradeLocker(project, packages)
-    else:
-        locker = PinReuseLocker(project)
-    success = lock(locker)
-    if not success:
-        return 1
-
-    project._l.write()
-    print("Written to project at", project.root)
-
-    if not options.sync:
-        return
-
-    from passa.operations.sync import sync
-    from passa.internals.synchronizers import Synchronizer
-
-    lockfile_diff = project.difference_lockfile(prev_lockfile)
-    default = bool(any(lockfile_diff.default))
-    develop = bool(any(lockfile_diff.develop))
-
-    syncer = Synchronizer(
-        project, default=default, develop=develop,
-        clean_unneeded=False,
-    )
-    success = sync(syncer)
-    if not success:
-        return 1
-
-    print("Synchronized project at", project.root)
+from .options import clean_group, sync_group, packages, strategy
 
 
 class Command(BaseCommand):
 
     name = "upgrade"
     description = "Upgrade packages in project."
-    parsed_main = main
+    arguments = [packages, strategy, clean_group, sync_group]
 
-    def add_arguments(self):
-        super(Command, self).add_arguments()
-        self.parser.add_argument(
-            "packages", metavar="package",
-            nargs="+",
-            help="package to upgrade (can be used multiple times)",
-        )
-        self.parser.add_argument(
-            "--strategy",
-            choices=["eager", "only-if-needed"],
-            default="only-if-needed",
-            help="how dependency upgrading is handled",
-        )
-        self.parser.add_argument(
-            "--no-sync", dest="sync",
-            action="store_false", default=True,
-            help="do not synchronize the environment",
-        )
-        self.parser.add_argument(
-            "--no-clean", dest="clean",
-            action="store_false", default=True,
-            help="do not uninstall packages not specified in Pipfile.lock",
-        )
+    def run(self, options):
+        return upgrade(project=options.project, strategy=options.strategy,
+                            sync=options.sync, packages=options.packages)
 
 
 if __name__ == "__main__":
-    Command.run_current_module()
+    Command.run_parser()
diff --git a/src/passa/internals/_pip.py b/src/passa/internals/_pip.py
deleted file mode 100644
index f73e241..0000000
--- a/src/passa/internals/_pip.py
+++ /dev/null
@@ -1,397 +0,0 @@
-# -*- coding=utf-8 -*-
-
-from __future__ import absolute_import, unicode_literals
-
-import contextlib
-import io
-import itertools
-import distutils.log
-import os
-
-import distlib.database
-import distlib.scripts
-import distlib.wheel
-import packaging.utils
-import pip_shims
-import setuptools.dist
-import six
-import vistir
-
-from ._pip_shims import VCS_SUPPORT, build_wheel as _build_wheel, unpack_url
-from .caches import CACHE_DIR
-from .utils import filter_sources
-
-
-@vistir.path.ensure_mkdir_p(mode=0o775)
-def _get_src_dir():
-    src = os.environ.get("PIP_SRC")
-    if src:
-        return src
-    virtual_env = os.environ.get("VIRTUAL_ENV")
-    if virtual_env:
-        return os.path.join(virtual_env, "src")
-    return os.path.join(os.getcwd(), "src")     # Match pip's behavior.
-
-
-def _prepare_wheel_building_kwargs(ireq):
-    download_dir = os.path.join(CACHE_DIR, "pkgs")
-    vistir.mkdir_p(download_dir)
-
-    wheel_download_dir = os.path.join(CACHE_DIR, "wheels")
-    vistir.mkdir_p(wheel_download_dir)
-
-    if ireq.source_dir is not None:
-        src_dir = ireq.source_dir
-    elif ireq.editable:
-        src_dir = _get_src_dir()
-    else:
-        src_dir = vistir.path.create_tracked_tempdir(prefix='passa-src')
-
-    # This logic matches pip's behavior, although I don't fully understand the
-    # intention. I guess the idea is to build editables in-place, otherwise out
-    # of the source tree?
-    if ireq.editable:
-        build_dir = src_dir
-    else:
-        build_dir = vistir.path.create_tracked_tempdir(prefix="passa-build")
-
-    return {
-        "build_dir": build_dir,
-        "src_dir": src_dir,
-        "download_dir": download_dir,
-        "wheel_download_dir": wheel_download_dir,
-    }
-
-
-def _get_pip_index_urls(sources):
-    index_urls = []
-    trusted_hosts = []
-    for source in sources:
-        url = source.get("url")
-        if not url:
-            continue
-        index_urls.append(url)
-        if source.get("verify_ssl", True):
-            continue
-        host = six.moves.urllib.parse.urlparse(source["url"]).hostname
-        trusted_hosts.append(host)
-    return index_urls, trusted_hosts
-
-
-class _PipCommand(pip_shims.Command):
-    name = "PipCommand"
-
-
-def _get_pip_session(trusted_hosts):
-    cmd = _PipCommand()
-    options, _ = cmd.parser.parse_args([])
-    options.cache_dir = CACHE_DIR
-    options.trusted_hosts = trusted_hosts
-    session = cmd._build_session(options)
-    return session
-
-
-def _get_finder(sources):
-    index_urls, trusted_hosts = _get_pip_index_urls(sources)
-    session = _get_pip_session(trusted_hosts)
-    finder = pip_shims.PackageFinder(
-        find_links=[],
-        index_urls=index_urls,
-        trusted_hosts=trusted_hosts,
-        allow_all_prereleases=True,
-        session=session,
-    )
-    return finder
-
-
-def _get_wheel_cache():
-    format_control = pip_shims.FormatControl(set(), set())
-    wheel_cache = pip_shims.WheelCache(CACHE_DIR, format_control)
-    return wheel_cache
-
-
-def _convert_hashes(values):
-    """Convert Pipfile.lock hash lines into InstallRequirement option format.
-
-    The option format uses a str-list mapping. Keys are hash algorithms, and
-    the list contains all values of that algorithm.
-    """
-    hashes = {}
-    if not values:
-        return hashes
-    for value in values:
-        try:
-            name, value = value.split(":", 1)
-        except ValueError:
-            name = "sha256"
-        if name not in hashes:
-            hashes[name] = []
-        hashes[name].append(value)
-    return hashes
-
-
-class WheelBuildError(RuntimeError):
-    pass
-
-
-def build_wheel(ireq, sources, hashes=None):
-    """Build a wheel file for the InstallRequirement object.
-
-    An artifact is downloaded (or read from cache). If the artifact is not a
-    wheel, build one out of it. The dynamically built wheel is ephemeral; do
-    not depend on its existence after the returned wheel goes out of scope.
-
-    If `hashes` is truthy, it is assumed to be a list of hashes (as formatted
-    in Pipfile.lock) to be checked against the download.
-
-    Returns a `distlib.wheel.Wheel` instance. Raises a `WheelBuildError` (a
-    `RuntimeError` subclass) if the wheel cannot be built.
-    """
-    kwargs = _prepare_wheel_building_kwargs(ireq)
-    finder = _get_finder(sources)
-
-    # Not for upgrade, hash not required. Hashes are not required here even
-    # when we provide them, because pip skips local wheel cache if we set it
-    # to True. Hashes are checked later if we need to download the file.
-    ireq.populate_link(finder, False, False)
-
-    # Ensure ireq.source_dir is set.
-    # This is intentionally set to build_dir, not src_dir. Comments from pip:
-    #   [...] if filesystem packages are not marked editable in a req, a non
-    #   deterministic error occurs when the script attempts to unpack the
-    #   build directory.
-    # Also see comments in `_prepare_wheel_building_kwargs()` -- If the ireq
-    # is editable, build_dir is actually src_dir, making the build in-place.
-    ireq.ensure_has_source_dir(kwargs["build_dir"])
-
-    # Ensure the source is fetched. For wheels, it is enough to just download
-    # because we'll use them directly. For an sdist, we need to unpack so we
-    # can build it.
-    if not ireq.editable or not pip_shims.is_file_url(ireq.link):
-        if ireq.is_wheel:
-            only_download = True
-            download_dir = kwargs["wheel_download_dir"]
-        else:
-            only_download = False
-            download_dir = kwargs["download_dir"]
-        ireq.options["hashes"] = _convert_hashes(hashes)
-        unpack_url(
-            ireq.link, ireq.source_dir, download_dir,
-            only_download=only_download, session=finder.session,
-            hashes=ireq.hashes(False), progress_bar="off",
-        )
-
-    if ireq.is_wheel:
-        # If this is a wheel, use the downloaded thing.
-        output_dir = kwargs["wheel_download_dir"]
-        wheel_path = os.path.join(output_dir, ireq.link.filename)
-    else:
-        # Othereise we need to build an ephemeral wheel.
-        wheel_path = _build_wheel(
-            ireq, vistir.path.create_tracked_tempdir(prefix="ephem"),
-            finder, _get_wheel_cache(), kwargs,
-        )
-        if wheel_path is None or not os.path.exists(wheel_path):
-            raise WheelBuildError
-    return distlib.wheel.Wheel(wheel_path)
-
-
-def _obtrain_ref(vcs_obj, src_dir, name, rev=None):
-    target_dir = os.path.join(src_dir, name)
-    target_rev = vcs_obj.make_rev_options(rev)
-    if not os.path.exists(target_dir):
-        vcs_obj.obtain(target_dir)
-    if (not vcs_obj.is_commit_id_equal(target_dir, rev) and
-            not vcs_obj.is_commit_id_equal(target_dir, target_rev)):
-        vcs_obj.update(target_dir, target_rev)
-    return vcs_obj.get_revision(target_dir)
-
-
-def get_vcs_ref(requirement):
-    backend = VCS_SUPPORT.get_backend(requirement.vcs)
-    vcs = backend(url=requirement.req.vcs_uri)
-    src = _get_src_dir()
-    name = requirement.normalized_name
-    ref = _obtrain_ref(vcs, src, name, rev=requirement.req.ref)
-    return ref
-
-
-def find_installation_candidates(ireq, sources):
-    finder = _get_finder(sources)
-    return finder.find_all_candidates(ireq.name)
-
-
-class RequirementUninstaller(object):
-    """A context manager to remove a package for the inner block.
-
-    This uses `UninstallPathSet` to control the workflow. If the inner block
-    exits correctly, the uninstallation is committed, otherwise rolled back.
-    """
-    def __init__(self, ireq, auto_confirm, verbose):
-        self.ireq = ireq
-        self.pathset = None
-        self.auto_confirm = auto_confirm
-        self.verbose = verbose
-
-    def __enter__(self):
-        self.pathset = self.ireq.uninstall(
-            auto_confirm=self.auto_confirm,
-            verbose=self.verbose,
-        )
-        return self.pathset
-
-    def __exit__(self, exc_type, exc_value, traceback):
-        if self.pathset is None:
-            return
-        if exc_type is None:
-            self.pathset.commit()
-        else:
-            self.pathset.rollback()
-
-
-def uninstall(name, **kwargs):
-    ireq = pip_shims.InstallRequirement.from_line(name)
-    return RequirementUninstaller(ireq, **kwargs)
-
-
-@contextlib.contextmanager
-def _suppress_distutils_logs():
-    """Hack to hide noise generated by `setup.py develop`.
-
-    There isn't a good way to suppress them now, so let's monky-patch.
-    See https://bugs.python.org/issue25392.
-    """
-    f = distutils.log.Log._log
-
-    def _log(log, level, msg, args):
-        if level >= distutils.log.ERROR:
-            f(log, level, msg, args)
-
-    distutils.log.Log._log = _log
-    yield
-    distutils.log.Log._log = f
-
-
-class NoopInstaller(object):
-    """An installer.
-
-    This class is not designed to be instantiated by itself, but used as a
-    common interface for subclassing.
-
-    An installer has two methods, `prepare()` and `install()`. Neither takes
-    arguments, and should be called in that order to prepare an installation
-    operation, and to actually install things.
-    """
-    def prepare(self):
-        pass
-
-    def install(self):
-        pass
-
-
-class EditableInstaller(NoopInstaller):
-    """Installer to handle editable.
-    """
-    def __init__(self, requirement):
-        ireq = requirement.as_ireq()
-        self.working_directory = ireq.setup_py_dir
-        self.setup_py = ireq.setup_py
-
-    def install(self):
-        with vistir.cd(self.working_directory), _suppress_distutils_logs():
-            # Access from Setuptools to ensure things are patched correctly.
-            setuptools.dist.distutils.core.run_setup(
-                self.setup_py, ["develop", "--no-deps"],
-            )
-
-
-class WheelInstaller(NoopInstaller):
-    """Installer by building a wheel.
-
-    The wheel is built during `prepare()`, and installed in `install()`.
-    """
-    def __init__(self, requirement, sources, paths):
-        self.ireq = requirement.as_ireq()
-        self.sources = filter_sources(requirement, sources)
-        self.hashes = requirement.hashes or None
-        self.paths = paths
-        self.wheel = None
-
-    def prepare(self):
-        self.wheel = build_wheel(self.ireq, self.sources, self.hashes)
-
-    def install(self):
-        self.wheel.install(self.paths, distlib.scripts.ScriptMaker(None, None))
-
-
-def _iter_egg_info_directories(root, name):
-    name = packaging.utils.canonicalize_name(name)
-    for parent, dirnames, filenames in os.walk(root):
-        matched_indexes = []
-        for i, dirname in enumerate(dirnames):
-            if not dirname.lower().endswith("egg-info"):
-                continue
-            egg_info_name = packaging.utils.canonicalize_name(dirname[:-9])
-            if egg_info_name != name:
-                continue
-            matched_indexes.append(i)
-            yield os.path.join(parent, dirname)
-
-        # Modify dirnames in-place to NOT look into egg-info directories.
-        # This is a documented behavior in stdlib.
-        for i in reversed(matched_indexes):
-            del dirnames[i]
-
-
-def _read_pkg_info(directory):
-    path = os.path.join(directory, "PKG-INFO")
-    try:
-        with io.open(path, encoding="utf-8", errors="replace") as f:
-            return f.read()
-    except (IOError, OSError):
-        return None
-
-
-def _find_egg_info(ireq):
-    """Find this package's .egg-info directory.
-
-    Due to how sdists are designed, the .egg-info directory cannot be reliably
-    found without running setup.py to aggregate all configurations. This
-    function instead uses some heuristics to locate the egg-info directory
-    that most likely represents this package.
-
-    The best .egg-info directory's path is returned as a string. None is
-    returned if no matches can be found.
-    """
-    root = ireq.setup_py_dir
-
-    directory_iterator = _iter_egg_info_directories(root, ireq.name)
-    try:
-        top_egg_info = next(directory_iterator)
-    except StopIteration:   # No egg-info found. Wat.
-        return None
-    directory_iterator = itertools.chain([top_egg_info], directory_iterator)
-
-    # Read the sdist's PKG-INFO to determine which egg_info is best.
-    pkg_info = _read_pkg_info(root)
-
-    # PKG-INFO not readable. Just return whatever comes first, I guess.
-    if pkg_info is None:
-        return top_egg_info
-
-    # Walk the sdist to find the egg-info with matching PKG-INFO.
-    for directory in directory_iterator:
-        egg_pkg_info = _read_pkg_info(directory)
-        if egg_pkg_info == pkg_info:
-            return directory
-
-    # Nothing matches...? Use the first one we found, I guess.
-    return top_egg_info
-
-
-def read_sdist_metadata(ireq):
-    egg_info_dir = _find_egg_info(ireq)
-    if not egg_info_dir:
-        return None
-    distribution = distlib.database.EggInfoDistribution(egg_info_dir)
-    return distribution.metadata
diff --git a/src/passa/internals/_pip_shims.py b/src/passa/internals/_pip_shims.py
deleted file mode 100644
index b2c7b6e..0000000
--- a/src/passa/internals/_pip_shims.py
+++ /dev/null
@@ -1,61 +0,0 @@
-# -*- coding=utf-8 -*-
-
-"""Shims to make the pip interface more consistent accross versions.
-
-There are currently two members:
-
-* VCS_SUPPORT is an instance of VcsSupport.
-* build_wheel abstracts the process to build a wheel out of a bunch parameters.
-* unpack_url wraps the actual function in pip to accept modern parameters.
-"""
-
-from __future__ import absolute_import, unicode_literals
-
-import pip_shims
-
-
-def _build_wheel_pre10(ireq, output_dir, finder, wheel_cache, kwargs):
-    kwargs.update({"wheel_cache": wheel_cache, "session": finder.session})
-    reqset = pip_shims.RequirementSet(**kwargs)
-    builder = pip_shims.WheelBuilder(reqset, finder)
-    return builder._build_one(ireq, output_dir)
-
-
-def _build_wheel_modern(ireq, output_dir, finder, wheel_cache, kwargs):
-    """Build a wheel.
-
-    * ireq: The InstallRequirement object to build
-    * output_dir: The directory to build the wheel in.
-    * finder: pip's internal Finder object to find the source out of ireq.
-    * kwargs: Various keyword arguments from `_prepare_wheel_building_kwargs`.
-    """
-    kwargs.update({"progress_bar": "off", "build_isolation": False})
-    with pip_shims.RequirementTracker() as req_tracker:
-        if req_tracker:
-            kwargs["req_tracker"] = req_tracker
-        preparer = pip_shims.RequirementPreparer(**kwargs)
-        builder = pip_shims.WheelBuilder(finder, preparer, wheel_cache)
-        return builder._build_one(ireq, output_dir)
-
-
-def _unpack_url_pre10(*args, **kwargs):
-    """Shim for unpack_url in various pip versions.
-
-    pip before 10.0 does not accept `progress_bar` here. Simply drop it.
-    """
-    kwargs.pop("progress_bar", None)
-    return pip_shims.unpack_url(*args, **kwargs)
-
-
-PIP_VERSION = pip_shims.utils._parse(pip_shims.pip_version)
-VERSION_10 = pip_shims.utils._parse("10")
-
-
-VCS_SUPPORT = pip_shims.VcsSupport()
-
-build_wheel = _build_wheel_modern
-unpack_url = pip_shims.unpack_url
-
-if PIP_VERSION < VERSION_10:
-    build_wheel = _build_wheel_pre10
-    unpack_url = _unpack_url_pre10
diff --git a/src/passa/internals/candidates.py b/src/passa/internals/candidates.py
index 67b0904..9076206 100644
--- a/src/passa/internals/candidates.py
+++ b/src/passa/internals/candidates.py
@@ -6,7 +6,8 @@
 import packaging.version
 import requirementslib
 
-from ._pip import find_installation_candidates, get_vcs_ref
+from packagebuilder import find_installation_candidates
+from ..models.caches import CACHE_DIR
 
 
 def _filter_matching_python_requirement(candidates, required_python):
@@ -57,11 +58,11 @@ def find_candidates(requirement, sources, requires_python, allow_prereleases):
     if not requirement.is_named:
         candidate = _copy_requirement(requirement)
         if candidate.is_vcs:
-            candidate.req.ref = get_vcs_ref(candidate)
+            candidate.req.ref = requirement.get_commit_hash()
         return [candidate]
 
     ireq = requirement.as_ireq()
-    icans = find_installation_candidates(ireq, sources)
+    icans = find_installation_candidates(ireq, sources, cache_dir=CACHE_DIR)
 
     if requires_python:
         matching_icans = list(_filter_matching_python_requirement(
diff --git a/src/passa/internals/dependencies.py b/src/passa/internals/dependencies.py
index 1fa3b0b..e8c6d31 100644
--- a/src/passa/internals/dependencies.py
+++ b/src/passa/internals/dependencies.py
@@ -6,6 +6,7 @@
 import os
 import sys
 
+import packagebuilder
 import packaging.specifiers
 import packaging.utils
 import packaging.version
@@ -13,8 +14,7 @@
 import requirementslib
 import six
 
-from ._pip import WheelBuildError, build_wheel, read_sdist_metadata
-from .caches import DependencyCache, RequiresPythonCache
+from ..models.caches import DependencyCache, RequiresPythonCache, CACHE_DIR
 from .markers import contains_extra, get_contained_extras, get_without_extra
 from .utils import get_pinned_version, is_pinned
 
@@ -224,20 +224,10 @@ def _get_dependencies_from_pip(ireq, sources):
     2. Read metadata out of the egg-info directory if it is present.
     """
     extras = ireq.extras or ()
-    try:
-        wheel = build_wheel(ireq, sources)
-    except WheelBuildError:
-        # XXX: This depends on a side effect of `build_wheel`. This block is
-        # reached when it fails to build an sdist, where the sdist would have
-        # been downloaded, extracted into `ireq.source_dir`, and partially
-        # built (hopefully containing .egg-info).
-        metadata = read_sdist_metadata(ireq)
-        if not metadata:
-            raise
-    else:
-        metadata = wheel.metadata
-    requirements = _read_requirements(metadata, extras)
-    requires_python = _read_requires_python(metadata)
+    builder = packagebuilder.BuiltDist(ireq, sources=sources, cache_dir=CACHE_DIR)
+    dist = builder.build()
+    requirements = _read_requirements(dist.metadata, extras)
+    requires_python = _read_requires_python(dist.metadata)
     return requirements, requires_python
 
 
diff --git a/src/passa/internals/markers.py b/src/passa/internals/markers.py
index 95efab9..08b4322 100644
--- a/src/passa/internals/markers.py
+++ b/src/passa/internals/markers.py
@@ -3,27 +3,56 @@
 from __future__ import absolute_import, unicode_literals
 
 from packaging.markers import Marker
+from .specifiers import PySpecs, gen_marker
+import six
+import distlib.markers
+
+six.add_move(six.MovedAttribute("Mapping", "collections", "collections.abc"))
+from six.moves import Mapping, reduce
+
+try:
+    from functools import lru_cache
+except ImportError:
+    from backports.functools_lru_cache import lru_cache
+
+
+def _ensure_marker(marker):
+    if not isinstance(marker, Marker):
+        return Marker(str(marker))
+    return marker
 
 
 def _strip_extra(elements):
-    """Remove the "extra == ..." operands from the list.
+    """Remove the "extra == ..." operands from the list."""
+
+    return _strip_marker_elem("extra", elements)
+
+
+def _strip_pyversion(elements):
+    return _strip_marker_elem("python_version", elements)
+
+
+def _strip_marker_elem(elem_name, elements):
+    """Remove the supplied element from the marker.
 
     This is not a comprehensive implementation, but relies on an important
-    characteristic of metadata generation: The "extra == ..." operand is always
+    characteristic of metadata generation: The element's operand is always
     associated with an "and" operator. This means that we can simply remove the
     operand and the "and" operator associated with it.
     """
+
     extra_indexes = []
+    preceding_operators = ["and"] if elem_name == "extra" else ["and", "or"]
     for i, element in enumerate(elements):
         if isinstance(element, list):
-            cancelled = _strip_extra(element)
+            cancelled = _strip_marker_elem(elem_name, element)
             if cancelled:
                 extra_indexes.append(i)
-        elif isinstance(element, tuple) and element[0].value == "extra":
+        elif isinstance(element, tuple) and element[0].value == elem_name:
             extra_indexes.append(i)
     for i in reversed(extra_indexes):
         del elements[i]
-        if i > 0 and elements[i - 1] == "and":
+        if i > 0 and elements[i - 1] in preceding_operators:
             # Remove the "and" before it.
             del elements[i - 1]
         elif elements:
@@ -34,6 +63,19 @@ def _strip_extra(elements):
     return (not elements)
 
 
+def _get_stripped_marker(marker, strip_func):
+    """Build a new marker which is cleaned according to `strip_func`"""
+
+    if not marker:
+        return None
+    marker = _ensure_marker(marker)
+    elements = marker._markers
+    strip_func(elements)
+    if elements:
+        return marker
+    return None
+
+
 def get_without_extra(marker):
     """Build a new marker without the `extra == ...` part.
 
@@ -43,18 +85,18 @@ def get_without_extra(marker):
     This could return `None` if the `extra == ...` part is the only one in the
     input marker.
     """
-    # TODO: Why is this very deep in the internals? Why is a better solution
-    # implementing it yourself when someone is already maintaining a codebase
-    # for this? It's literally a grammar implementation that is required to
-    # meet the demands of a pep... -d
-    if not marker:
-        return None
-    marker = Marker(str(marker))
-    elements = marker._markers
-    _strip_extra(elements)
-    if elements:
-        return marker
-    return None
+
+    return _get_stripped_marker(marker, _strip_extra)
+
+
+def get_without_pyversion(marker):
+    """Built a new marker without the `python_version` part.
+
+    This could return `None` if the `python_version` section is the only section in the
+    marker.
+    """
+
+    return _get_stripped_marker(marker, _strip_pyversion)
 
 
 def _markers_collect_extras(markers, collection):
@@ -68,6 +110,24 @@ def _markers_collect_extras(markers, collection):
             _markers_collect_extras(el, collection)
 
 
+def _markers_collect_pyversions(markers, collection):
+    local_collection = []
+    marker_format_str = "{0}"
+    for i, el in enumerate(reversed(markers)):
+        if (isinstance(el, tuple) and
+                el[0].value == "python_version"):
+            new_marker = str(gen_marker(el))
+            local_collection.append(marker_format_str.format(new_marker))
+        elif isinstance(el, six.string_types):
+            local_collection.append(el)
+        elif isinstance(el, list):
+            _markers_collect_pyversions(el, local_collection)
+    if local_collection:
+        local_collection = "{0}".format(" ".join(local_collection))
+        collection.append(local_collection)
+
+
+@lru_cache(maxsize=128)
 def get_contained_extras(marker):
     """Collect "extra == ..." operands from a marker.
 
@@ -75,27 +135,116 @@ def get_contained_extras(marker):
     """
     if not marker:
         return set()
-    marker = Marker(str(marker))
     extras = set()
+    marker = _ensure_marker(marker)
     _markers_collect_extras(marker._markers, extras)
     return extras
 
 
+def get_contained_pyversions(marker):
+    """Collect all `python_version` operands from a marker.
+
+    Returns a set of :class:`~passa.internals.specifiers.PySpecs` instances.
+    """
+
+    collection = []
+    if not marker:
+        return set()
+    marker = _ensure_marker(marker)
+    # Collect the (Variable, Op, Value) tuples and string joiners from the marker
+    _markers_collect_pyversions(marker._markers, collection)
+    marker_str = " ".join(collection)
+    if not marker_str:
+        return set()
+    # Use the distlib dictionary parser to create a dictionary 'trie' which is a bit
+    # easier to reason about
+    marker_dict = distlib.markers.parse_marker(marker_str)[0]
+    version_set = set()
+    pyversions = parse_marker_dict(marker_dict)
+    if isinstance(pyversions, set):
+        version_set.update(pyversions)
+    else:
+        version_set.add(pyversions)
+    # Each distinct element in the set was separated by an "and" operator in the marker
+    # So we will need to reduce them with an intersection here rather than a union
+    # in order to find the boundaries
+    versions = reduce(lambda x, y: x & y, version_set)
+    if not versions:
+        return PySpecs()
+    return versions
+
+
 def _markers_contains_extra(markers):
     # Optimization: the marker element is usually appended at the end.
+    return _markers_contains_key(markers, "extra")
+
+
+def _markers_contains_pyversion(markers):
+    return _markers_contains_key(markers, "python_version")
+
+
+def _markers_contains_key(markers, key):
     for element in reversed(markers):
-        if isinstance(element, tuple) and element[0].value == "extra":
+        if isinstance(element, tuple) and element[0].value == key:
             return True
         elif isinstance(element, list):
-            if _markers_contains_extra(element):
+            if _markers_contains_key(element, key):
                 return True
     return False
 
 
+@lru_cache(maxsize=128)
 def contains_extra(marker):
     """Check whehter a marker contains an "extra == ..." operand.
     """
     if not marker:
         return False
-    marker = Marker(str(marker))
+    marker = _ensure_marker(marker)
     return _markers_contains_extra(marker._markers)
+
+
+@lru_cache(maxsize=128)
+def contains_pyversion(marker):
+    """Check whether a marker contains a python_version operand.
+    """
+
+    if not marker:
+        return False
+    marker = _ensure_marker(marker)
+    return _markers_contains_pyversion(marker._markers)
+
+
+def parse_marker_dict(marker_dict):
+    op = marker_dict["op"]
+    lhs = marker_dict["lhs"]
+    rhs = marker_dict["rhs"]
+    # This is where the spec sets for each side land if we have an "or" operator
+    sides = set()
+    # And if we hit the end of the parse tree we use this format string to make a marker
+    format_string = "{lhs} {op} {rhs}"
+    # Essentially we will iterate over each side of the parsed marker if either one is
+    # A mapping instance (i.e. a dictionary) and recursively parse and reduce the specset
+    # Union the "and" specs, intersect the "or"s to find the most appropriate range
+    if any(issubclass(type(side), Mapping) for side in (lhs, rhs)):
+        for side in (lhs, rhs):
+            specs = PySpecs()
+            if issubclass(type(side), Mapping):
+                specs.add(parse_marker_dict(side))
+            else:
+                # This is the easiest way to go from a string to a PySpec instance
+                specs.add(PySpecs.from_marker(Marker(side)))
+            sides.add(specs)
+        if op == "and":
+            # When we are "and"-ing things together, it probably makes the most sense
+            # to reduce them here into a single PySpec instance
+            if not sides:
+                sides = [lhs, rhs]
+            sides = reduce(lambda x, y: x | y, sides)
+            return PySpecs.from_marker(Marker(str(sides)))
+        # Actually when we "or" things as well we can also just turn them into a reduced
+        # set using this logic now
+        return reduce(lambda x, y: x & y, sides)
+    else:
+        # At the tip of the tree we are dealing with strings all around and they just need
+        # to be smashed together
+        return PySpecs.from_marker(Marker(format_string.format(**marker_dict)))
diff --git a/src/passa/internals/specifiers.py b/src/passa/internals/specifiers.py
index 75afb6a..14654e8 100644
--- a/src/passa/internals/specifiers.py
+++ b/src/passa/internals/specifiers.py
@@ -5,14 +5,30 @@
 import itertools
 import operator
 
-from packaging.specifiers import SpecifierSet, Specifier
+import six
+
+from packaging.markers import Marker
+from packaging.specifiers import Specifier, SpecifierSet
+import packaging.version
+
 from vistir.misc import dedup
 
+six.add_move(six.MovedAttribute("Set", "collections", "collections.abc"))
+from six.moves import reduce, Set
+
+
+try:
+    from functools import lru_cache
+except ImportError:
+    from backports.functools_lru_cache import lru_cache
+
 
+@lru_cache(maxsize=128)
 def _tuplize_version(version):
-    return tuple(int(x) for x in version.split("."))
+    return tuple(int(x) for x in filter(lambda i: i != "*", version.split(".")))
 
 
+@lru_cache(maxsize=128)
 def _format_version(version):
     return ".".join(str(i) for i in version)
 
@@ -21,52 +37,73 @@ def _format_version(version):
 REPLACE_RANGES = {">": ">=", "<=": "<"}
 
 
+@lru_cache(maxsize=128)
 def _format_pyspec(specifier):
     if isinstance(specifier, str):
         if not any(op in specifier for op in Specifier._operators.keys()):
             specifier = "=={0}".format(specifier)
         specifier = Specifier(specifier)
-    if specifier.operator == "==" and specifier.version.endswith(".*"):
-        specifier = Specifier("=={0}".format(specifier.version[:-2]))
+    version = specifier.version.replace(".*", "")
+    if ".*" in specifier.version:
+        specifier = Specifier("{0}{1}".format(specifier.operator, version))
     try:
         op = REPLACE_RANGES[specifier.operator]
     except KeyError:
         return specifier
-    version = specifier.version.replace(".*", "")
     curr_tuple = _tuplize_version(version)
     try:
         next_tuple = (curr_tuple[0], curr_tuple[1] + 1)
     except IndexError:
         next_tuple = (curr_tuple[0], 1)
+    if not next_tuple[1] <= PySpecs.MAX_VERSIONS[next_tuple[0]]:
+        if (specifier.operator == "<"
+                and next_tuple[1] - 1 <= PySpecs.MAX_VERSIONS[next_tuple[0]]):
+            op = "<="
+            next_tuple = (next_tuple[0], next_tuple[1] - 1)
+        else:
+            return specifier
     specifier = Specifier("{0}{1}".format(op, _format_version(next_tuple)))
     return specifier
 
 
+@lru_cache(maxsize=128)
 def _get_specs(specset):
+    if specset is None:
+        return
     if isinstance(specset, Specifier):
         specset = str(specset)
     if isinstance(specset, str):
         specset = SpecifierSet(specset.replace(".*", ""))
-    return [
-        (spec._spec[0], _tuplize_version(spec._spec[1]))
-        for spec in getattr(specset, "_specs", [])
-    ]
+    result = []
+    for spec in set(specset):
+        version = spec.version
+        op = spec.operator
+        if op in ("in", "not in"):
+            versions = version.split(",")
+            op = "==" if op == "in" else "!="
+            for ver in versions:
+                result.append((op, _tuplize_version(ver.strip())))
+        else:
+            result.append((spec.operator, _tuplize_version(spec.version)))
+    return result
 
 
+@lru_cache(maxsize=128)
 def _group_by_op(specs):
     specs = [_get_specs(x) for x in list(specs)]
     flattened = [(op, version) for spec in specs for op, version in spec]
-    specs = sorted(flattened, key=operator.itemgetter(1))
+    specs = sorted(flattened)
     grouping = itertools.groupby(specs, key=operator.itemgetter(0))
     return grouping
 
 
+@lru_cache(maxsize=128)
 def cleanup_pyspecs(specs, joiner="or"):
     specs = {_format_pyspec(spec) for spec in specs}
     # for != operator we want to group by version
     # if all are consecutive, join as a list
     results = set()
-    for op, versions in _group_by_op(specs):
+    for op, versions in _group_by_op(tuple(specs)):
         versions = [version[1] for version in versions]
         versions = sorted(dedup(versions))
         # if we are doing an or operation, we need to use the min for >=
@@ -113,24 +150,338 @@ def cleanup_pyspecs(specs, joiner="or"):
     return results
 
 
-def pyspec_from_markers(marker):
-    if marker._markers[0][0] != 'python_version':
+def fix_version_tuple(version_tuple):
+    op, version = version_tuple
+    max_allowed = PySpecs.MAX_VERSIONS[version[0]]
+    if op == "<" and version[1] > max_allowed and version[1] - 1 <= max_allowed:
+        op = "<="
+        version = (version[0], version[1] - 1)
+    return (op, version)
+
+
+@lru_cache(maxsize=128)
+def get_versions(specset, group_by_operator=True):
+    specs = [_get_specs(x) for x in list(tuple(specset))]
+    initial_sort_key = lambda k: (k[0], k[1])
+    initial_grouping_key = operator.itemgetter(0)
+    if not group_by_operator:
+        initial_grouping_key = operator.itemgetter(1)
+        initial_sort_key = operator.itemgetter(1)
+    version_tuples = sorted(
+        set((op, version) for spec in specs for op, version in spec),
+        key=initial_sort_key
+    )
+    version_tuples = [fix_version_tuple(t) for t in version_tuples]
+    op_groups = [
+        (grp, list(map(operator.itemgetter(1), keys)))
+        for grp, keys in itertools.groupby(version_tuples, key=initial_grouping_key)
+    ]
+    versions = [
+        (op, packaging.version.parse(".".join(str(v) for v in val)))
+        for op, vals in op_groups for val in vals
+    ]
+    return versions
+
+
+def get_next_python(version):
+    version_index = ALL_PYTHON_VERSIONS.index(version)
+    return ALL_PYTHON_VERSIONS[version_index + 1]
+
+
+def get_previous_python(version):
+    version_index = ALL_PYTHON_VERSIONS.index(version)
+    return ALL_PYTHON_VERSIONS[version_index - 1]
+
+
+def gen_marker(mkr):
+    m = Marker("python_version == '1'")
+    m._markers.pop()
+    m._markers.append(mkr)
+    return m
+
+
+class PySpecs(Set):
+
+    MAX_VERSIONS = {
+        2: 7,
+        3: 9
+    }
+
+    def __init__(self, specs=None):
+        if not specs:
+            specs = SpecifierSet()
+        self.specifierset = specs
+        self.previous_specifierset = None
+        self.cleaned_tuples = set()
+        self.markers = None
+        self.clean()
+
+    def __key(self):
+        return tuple(sorted(self.specifierset, key=operator.attrgetter("_spec")))
+
+    def __contains__(self, other):
+        # The current specifierset fully has every value in the supplied specifierset
+        if not other.as_set - self.as_set:
+            return True
+        return False
+
+    def __eq__(self, other):
+        return self.__key() == other.__key()
+
+    def __hash__(self):
+        return hash(self.__key())
+
+    def __repr__(self):
+        return u"PySpecs({0!r})".format(str(self.specifierset))
+
+    def __len__(self):
+        return len(self.cleaned_tuples)
+
+    def __iter__(self):
+        for version in self.as_string_set:
+            yield version
         return
-    op = marker._markers[0][1].value
-    version = marker._markers[0][2].value
-    specset = set()
-    if op == "in":
-        specset.update(
-            Specifier("=={0}".format(v.strip()))
-            for v in version.split(",")
-        )
-    elif op == "not in":
-        specset.update(
-            Specifier("!={0}".format(v.strip()))
-            for v in version.split(",")
+
+    def clean(self):
+        if len(set(self.specifierset)) == 1:
+            spec = next(iter(spec for spec in self.specifierset), None)
+            if spec:
+                self.cleaned_tuples.add((spec.operator, spec.version))
+        else:
+            self.cleaned_tuples = cleanup_pyspecs(self.specifierset, joiner="and")
+            self.specifierset = self.as_specset
+
+    def add(self, other):
+        if not isinstance(other, self.__class__):
+            if isinstance(other, SpecifierSet):
+                other = PySpecs(other)
+            else:
+                raise TypeError("Cannot add type {0!r} to PySpecs".format(type(other)))
+        new_specifierset = SpecifierSet()
+        new_specifierset &= self.as_specset
+        try:
+            new_specifierset &= other.as_specset
+        except AttributeError:
+            pass
+        new_pyspec = PySpecs(new_specifierset)
+        self.specifierset = new_pyspec.specifierset
+        self.cleaned_tuples = new_pyspec.cleaned_tuples
+
+    @property
+    @lru_cache(maxsize=128)
+    def as_specset(self):
+        specs = set()
+        for spec in self.cleaned_tuples:
+            op, value = spec
+            if op in ('in', 'not in'):
+                new_op = '!=' if op == 'not in' else '=='
+                for val in value.split(","):
+                    specs.add(Specifier("{0}{1}".format(new_op, val)))
+            else:
+                specs.add(Specifier("{0}{1}".format(op, value)))
+        specifierset = SpecifierSet()
+        specifierset._specs = frozenset(specs)
+        return specifierset
+
+    @property
+    @lru_cache(maxsize=128)
+    def as_set(self):
+        return set(self.specifierset)
+
+    @property
+    @lru_cache(maxsize=128)
+    def as_string_set(self):
+        returnval = set()
+        if len(self.cleaned_tuples) == 1:
+            val = next(iter(spec for spec in self.cleaned_tuples), None)
+            if val:
+                returnval.add("python_version {0[0]} '{0[1]}'".format(val))
+            return returnval
+        return set(
+            "python_version {0[0]} '{0[1]}'".format(s)
+            for s in sorted(self.cleaned_tuples)
         )
-    else:
-        specset.add(Specifier("".join([op, version])))
-    if specset:
-        return specset
-    return None
+
+    @property
+    @lru_cache(maxsize=128)
+    def marker_set(self):
+        markerset = {Marker(spec) for spec in self.as_string_set}
+        return markerset
+
+    @property
+    @lru_cache(maxsize=128)
+    def marker_string(self):
+        marker_string = " and ".join(sorted(str(m) for m in self.marker_set))
+        if not marker_string:
+            return ""
+        return str(Marker(marker_string))
+
+    @property
+    @lru_cache(maxsize=128)
+    def as_markers(self):
+        if not self.marker_string:
+            return ""
+        marker = Marker(self.marker_string)
+        return marker
+
+    @lru_cache(maxsize=128)
+    def __str__(self):
+        string_repr = "{0}".format(str(self.marker_string))
+        return string_repr
+
+    def __bool__(self):
+        return bool(self.specifierset)
+
+    def __nonzero__(self):  # Python 2.
+        return self.__bool__()
+
+    def get_versions(self, group_by_operator=True):
+        return get_versions(self.specifierset, group_by_operator=group_by_operator)
+
+    def get_versions_in_specset(self):
+        return set([v[1] for v in self.get_versions() if v[1] in self.specifierset])
+
+    def get_version_excludes(self):
+        return set(v[1] for v in self.get_versions() if v[1] not in self.specifierset)
+
+    def group_specs(self, specs=None, handle_exclusions=True):
+        if not specs:
+            specs = self.get_versions(group_by_operator=handle_exclusions)
+        else:
+            specs = get_versions(specs, group_by_operator=handle_exclusions)
+        pyversions = enumerate(self.get_versions(group_by_operator=handle_exclusions))
+
+        def get_version(v):
+            return ALL_PYTHON_VERSIONS.index(v[1][1])
+
+        excludes = set()
+        ranges = set()
+
+        # group the versions on their index from ALL_PYTHON_VERSIONS - their index here
+        # consecutive elements will share a group, e.g.
+        # ALL_PYTHON_VERSIONS.index(parse_version("2.7")) == 7, 3.0 == 8, 3.1 == 9
+        # if 2.7 is element 1, (7 - 1) = 6, if 3.0 is element 2, (8 - 2) = 6
+        # and they will share a group (i.e. they are consecutive)
+        for k, grp in itertools.groupby(pyversions, lambda t: get_version(t) - t[0]):
+            version_group = list(grp)
+            op = next(iter(v[1][0] for v in version_group), None)
+            _versions = [v[1][1] for v in version_group]
+            if op == "!=":
+                excludes.update(set(_versions))
+            else:
+                min_ = min(_versions)
+                max_ = max(_versions)
+                if len(_versions) == 1 or str(min_) == str(max_):
+                    ranges.add((min_,))
+                else:
+                    ranges.add((min_, max_))
+        return ranges, excludes
+
+    def create_specset_from_ranges(self, specset=None, ranges=None, excludes=None):
+        group_args = {"handle_exclusions": False}
+        if specset:
+            group_args["specs"] = specset
+        if not ranges:
+            ranges, _ = self.group_specs(**group_args)
+        if not excludes:
+            group_args["handle_exclusions"] = True
+            _, excludes = self.group_specs(**group_args)
+        spec_ranges = set()
+        for range_ in ranges:
+            if len(range_) == 1:
+                spec_ranges.add(Specifier("=={0}".format(str(next(iter(range_))))))
+            else:
+                min_, max_ = range_
+                if min_ == max_:
+                    spec_ranges.add("<={0}").format(min_)
+                else:
+                    spec_ranges.add(Specifier(">={0}".format(str(min_))))
+                    spec_ranges.add(Specifier("<={0}".format(str(max_))))
+        for exclude in excludes:
+            spec_ranges.add(Specifier("!={0}".format(str(exclude))))
+        new_specset = SpecifierSet()
+        new_specset._specs = frozenset(spec_ranges)
+
+    @lru_cache(maxsize=128)
+    def __and__(self, other):
+        # Unintuitive perhaps, but this is for "x or y" and needs to handle the
+        # widest possible range encapsulated by the two using the intersection
+        if not isinstance(other, PySpecs):
+            other = PySpecs(other)
+        if self == other:
+            return self
+        new_specset = SpecifierSet()
+        own_ranges, own_excludes = self.group_specs()
+        other_ranges, other_excludes = other.group_specs()
+        # In order to do an "or" propertly we need to intersect the "good" versions
+        intersection = self.get_versions_in_specset() & other.get_versions_in_specset()
+        # And then we need to union the "bad" versions
+        excludes = own_excludes | other_excludes
+        new_specset = self.create_specset_from_ranges(ranges=intersection, excludes=excludes)
+        return PySpecs(new_specset)
+
+    @lru_cache(maxsize=128)
+    def __or__(self, specset):
+        if not isinstance(specset, PySpecs):
+            specset = PySpecs(specset)
+        if str(self) == str(specset):
+            return self
+        combined_set = self.as_set | specset.as_set
+        new_specset = SpecifierSet()
+        new_specset._specs = frozenset(combined_set)
+        new_pyspec = PySpecs(new_specset)
+        return new_pyspec
+
+    @classmethod
+    def from_marker(cls, marker):
+        if not marker:
+            return PySpecs()
+        if len(marker._markers) > 1:
+            specs = PySpecs()
+            markers = sorted([
+                el for el in marker._markers
+                if isinstance(el, tuple)
+            ], key=lambda x: x[2].value)
+            for mkr in markers:
+                specs.add(cls.from_marker(gen_marker(mkr)))
+            return specs
+        if marker._markers[0][0].value != 'python_version':
+            return
+        op = marker._markers[0][1].value
+        version = marker._markers[0][2].value
+        specset = set()
+        if op == "in":
+            specset.update(
+                Specifier("=={0}".format(v.strip()))
+                for v in version.split(",")
+            )
+        elif op == "not in":
+            versions = [v.strip() for v in version.split(",")]
+            bad_versions = ["3.0", "3.1", "3.2", "3.3"]
+            if len(versions) >= 2 and any(v in versions for v in bad_versions):
+                versions = bad_versions
+            specset.update(
+                Specifier("!={0}".format(v.strip()))
+                for v in sorted(bad_versions)
+            )
+        else:
+            specset.add(Specifier("".join([op, version])))
+        if specset:
+            specifierset = SpecifierSet()
+            specifierset._specs = frozenset(specset)
+            newset = cls(specifierset)
+            return newset
+        return None
+
+
+def get_all_python_versions():
+    major_versions = list(PySpecs.MAX_VERSIONS.keys())
+    versions = (
+        "{0}.{1}".format(major, minor) for major in major_versions
+        for minor in range(PySpecs.MAX_VERSIONS[major] + 1)
+    )
+    versions = (packaging.version.parse(v) for v in versions)
+    return versions
+
+
+ALL_PYTHON_VERSIONS = sorted(get_all_python_versions())
diff --git a/src/passa/internals/synchronizers.py b/src/passa/internals/synchronizers.py
deleted file mode 100644
index 7ccce23..0000000
--- a/src/passa/internals/synchronizers.py
+++ /dev/null
@@ -1,214 +0,0 @@
-# -*- coding=utf-8 -*-
-
-from __future__ import absolute_import, unicode_literals
-
-import collections
-import contextlib
-import os
-import sys
-import sysconfig
-
-import pkg_resources
-
-import packaging.markers
-import packaging.version
-import requirementslib
-
-from ._pip import uninstall, EditableInstaller, WheelInstaller
-
-
-def _is_installation_local(name):
-    """Check whether the distribution is in the current Python installation.
-
-    This is used to distinguish packages seen by a virtual environment. A venv
-    may be able to see global packages, but we don't want to mess with them.
-    """
-    loc = os.path.normcase(pkg_resources.working_set.by_key[name].location)
-    pre = os.path.normcase(sys.prefix)
-    return os.path.commonprefix([loc, pre]) == pre
-
-
-def _is_up_to_date(distro, version):
-    # This is done in strings to avoid type mismatches caused by vendering.
-    return str(version) == str(packaging.version.parse(distro.version))
-
-
-GroupCollection = collections.namedtuple("GroupCollection", [
-    "uptodate", "outdated", "noremove", "unneeded",
-])
-
-
-def _group_installed_names(packages):
-    """Group locally installed packages based on given specifications.
-
-    `packages` is a name-package mapping that are used as baseline to
-    determine how the installed package should be grouped.
-
-    Returns a 3-tuple of disjoint sets, all containing names of installed
-    packages:
-
-    * `uptodate`: These match the specifications.
-    * `outdated`: These installations are specified, but don't match the
-        specifications in `packages`.
-    * `unneeded`: These are installed, but not specified in `packages`.
-    """
-    groupcoll = GroupCollection(set(), set(), set(), set())
-
-    for distro in pkg_resources.working_set:
-        name = distro.key
-        try:
-            package = packages[name]
-        except KeyError:
-            groupcoll.unneeded.add(name)
-            continue
-
-        r = requirementslib.Requirement.from_pipfile(name, package)
-        if not r.is_named:
-            # Always mark non-named. I think pip does something similar?
-            groupcoll.outdated.add(name)
-        elif not _is_up_to_date(distro, r.get_version()):
-            groupcoll.outdated.add(name)
-        else:
-            groupcoll.uptodate.add(name)
-
-    return groupcoll
-
-
-@contextlib.contextmanager
-def _remove_package(name):
-    if name is None or not _is_installation_local(name):
-        yield None
-        return
-    with uninstall(name, auto_confirm=True, verbose=False) as uninstaller:
-        yield uninstaller
-
-
-def _get_packages(lockfile, default, develop):
-    # Don't need to worry about duplicates because only extras can differ.
-    # Extras don't matter because they only affect dependencies, and we
-    # don't install dependencies anyway!
-    packages = {}
-    if default:
-        packages.update(lockfile.default._data)
-    if develop:
-        packages.update(lockfile.develop._data)
-    return packages
-
-
-def _build_paths():
-    """Prepare paths for distlib.wheel.Wheel to install into.
-    """
-    paths = sysconfig.get_paths()
-    return {
-        "prefix": sys.prefix,
-        "data": paths["data"],
-        "scripts": paths["scripts"],
-        "headers": paths["include"],
-        "purelib": paths["purelib"],
-        "platlib": paths["platlib"],
-    }
-
-
-PROTECTED_FROM_CLEAN = {"setuptools", "pip", "wheel"}
-
-
-def _clean(names):
-    cleaned = set()
-    for name in names:
-        if name in PROTECTED_FROM_CLEAN:
-            continue
-        with _remove_package(name) as uninst:
-            if uninst:
-                cleaned.add(name)
-    return cleaned
-
-
-class Synchronizer(object):
-    """Helper class to install packages from a project's lock file.
-    """
-    def __init__(self, project, default, develop, clean_unneeded):
-        self._root = project.root   # Only for repr.
-        self.packages = _get_packages(project.lockfile, default, develop)
-        self.sources = project.lockfile.meta.sources._data
-        self.paths = _build_paths()
-        self.clean_unneeded = clean_unneeded
-
-    def __repr__(self):
-        return "<{0} @ {1!r}>".format(type(self).__name__, self._root)
-
-    def sync(self):
-        groupcoll = _group_installed_names(self.packages)
-
-        installed = set()
-        updated = set()
-        cleaned = set()
-
-        # TODO: Show a prompt to confirm cleaning. We will need to implement a
-        # reporter pattern for this as well.
-        if self.clean_unneeded:
-            names = _clean(groupcoll.unneeded)
-            cleaned.update(names)
-
-        # TODO: Specify installation order? (pypa/pipenv#2274)
-        installers = []
-        for name, package in self.packages.items():
-            r = requirementslib.Requirement.from_pipfile(name, package)
-            name = r.normalized_name
-            if name in groupcoll.uptodate:
-                continue
-            markers = r.markers
-            if markers and not packaging.markers.Marker(markers).evaluate():
-                continue
-            r.markers = None
-            if r.editable:
-                installer = EditableInstaller(r)
-            else:
-                installer = WheelInstaller(r, self.sources, self.paths)
-            try:
-                installer.prepare()
-            except Exception as e:
-                if os.environ.get("PASSA_NO_SUPPRESS_EXCEPTIONS"):
-                    raise
-                print("failed to prepare {0!r}: {1}".format(
-                    r.as_line(include_hashes=False), e,
-                ))
-            else:
-                installers.append((name, installer))
-
-        for name, installer in installers:
-            if name in groupcoll.outdated:
-                name_to_remove = name
-            else:
-                name_to_remove = None
-            try:
-                with _remove_package(name_to_remove):
-                    installer.install()
-            except Exception as e:
-                if os.environ.get("PASSA_NO_SUPPRESS_EXCEPTIONS"):
-                    raise
-                print("failed to install {0!r}: {1}".format(
-                    r.as_line(include_hashes=False), e,
-                ))
-                continue
-            if name in groupcoll.outdated or name in groupcoll.noremove:
-                updated.add(name)
-            else:
-                installed.add(name)
-
-        return installed, updated, cleaned
-
-
-class Cleaner(object):
-    """Helper class to clean packages not in a project's lock file.
-    """
-    def __init__(self, project, default, develop):
-        self._root = project.root   # Only for repr.
-        self.packages = _get_packages(project.lockfile, default, develop)
-
-    def __repr__(self):
-        return "<{0} @ {1!r}>".format(type(self).__name__, self._root)
-
-    def clean(self):
-        groupcoll = _group_installed_names(self.packages)
-        cleaned = _clean(groupcoll.unneeded)
-        return cleaned
diff --git a/src/passa/internals/utils.py b/src/passa/internals/utils.py
index 8f8e6fd..0dd75d1 100644
--- a/src/passa/internals/utils.py
+++ b/src/passa/internals/utils.py
@@ -82,21 +82,6 @@ def is_pinned(ireq):
     return True
 
 
-def filter_sources(requirement, sources):
-    """Returns a filtered list of sources for this requirement.
-
-    This considers the index specified by the requirement, and returns only
-    matching source entries if there is at least one.
-    """
-    if not sources or not requirement.index:
-        return sources
-    filtered_sources = [
-        source for source in sources
-        if source.get("name") == requirement.index
-    ]
-    return filtered_sources or sources
-
-
 def get_allow_prereleases(requirement, global_setting):
     # TODO: Implement per-package prereleases flag. (pypa/pipenv#1696)
     return global_setting
diff --git a/src/passa/models/__init__.py b/src/passa/models/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/passa/internals/caches.py b/src/passa/models/caches.py
similarity index 98%
rename from src/passa/internals/caches.py
rename to src/passa/models/caches.py
index 6d3131f..bda8cc2 100644
--- a/src/passa/internals/caches.py
+++ b/src/passa/models/caches.py
@@ -13,12 +13,13 @@
 import requests
 import vistir
 
-from ._pip_shims import VCS_SUPPORT
-from .utils import get_pinned_version
+from ..internals.utils import get_pinned_version
 
 
 CACHE_DIR = os.environ.get("PASSA_CACHE_DIR", appdirs.user_cache_dir("passa"))
 
+VCS_SUPPORT = pip_shims.VcsSupport()
+
 
 class HashCache(pip_shims.SafeFileCache):
     """Caches hashes of PyPI artifacts so we do not need to re-download them.
diff --git a/src/passa/internals/lockers.py b/src/passa/models/lockers.py
similarity index 95%
rename from src/passa/internals/lockers.py
rename to src/passa/models/lockers.py
index b567c46..53f1cab 100644
--- a/src/passa/internals/lockers.py
+++ b/src/passa/models/lockers.py
@@ -4,18 +4,19 @@
 
 import itertools
 
+import resolvelib
+
 import plette
 import requirementslib
-import resolvelib
 import vistir
 
+from ..internals.hashes import get_hashes
+from ..internals.reporters import StdOutReporter
+from ..internals.traces import trace_graph
+from ..internals.utils import identify_requirment
 from .caches import HashCache
-from .hashes import get_hashes
 from .metadata import set_metadata
 from .providers import BasicProvider, EagerUpgradeProvider, PinReuseProvider
-from .reporters import StdOutReporter
-from .traces import trace_graph
-from .utils import identify_requirment
 
 
 def _get_requirements(model, section_name):
@@ -70,6 +71,9 @@ def _collect_derived_entries(state, traces, identifiers):
                 extras[name].extend(requirement.extras)
             except KeyError:
                 extras[name] = list(requirement.extras)
+        if requirement.editable and requirement.markers:
+            requirement.markers = set()
+            requirement.req.req.markers = set()
         entries[name] = next(iter(requirement.as_pipfile().values()))
     for name, ext in extras.items():
         entries[name]["extras"] = ext
diff --git a/src/passa/internals/metadata.py b/src/passa/models/metadata.py
similarity index 58%
rename from src/passa/internals/metadata.py
rename to src/passa/models/metadata.py
index 9709c53..27990a8 100644
--- a/src/passa/internals/metadata.py
+++ b/src/passa/models/metadata.py
@@ -4,14 +4,19 @@
 
 import copy
 import itertools
+import operator
 
 import packaging.markers
 import packaging.specifiers
 import vistir
 import vistir.misc
 
-from .markers import get_without_extra
-from .specifiers import cleanup_pyspecs, pyspec_from_markers
+from six.moves import reduce
+
+from ..internals.markers import (
+    get_without_extra, get_without_pyversion, get_contained_pyversions
+)
+from ..internals.specifiers import PySpecs
 
 
 def dedup_markers(s):
@@ -28,35 +33,52 @@ class MetaSet(object):
     """
     def __init__(self):
         self.markerset = frozenset()
-        self.pyspecset = packaging.specifiers.SpecifierSet()
+        self.pyspecset = PySpecs()
 
     def __repr__(self):
         return "MetaSet(markerset={0!r}, pyspecset={1!r})".format(
             ",".join(sorted(self.markerset)), str(self.pyspecset),
         )
 
+    def __key(self):
+        return (tuple(self.markerset), hash(tuple(self.pyspecset)))
+
+    def __hash__(self):
+        return hash(self.__key())
+
+    def __eq__(self, other):
+        return self.__key() == other.__key()
+
+    def __len__(self):
+        return len(self.markerset) + len(self.pyspecset)
+
+    def __iter__(self):
+        return itertools.chain(self.markerset, self.pyspecset)
+
+    def __lt__(self, other):
+        return operator.lt(self.__key(), other.__key())
+
+    def __le__(self, other):
+        return operator.le(self.__key(), other.__key())
+
+    def __ge__(self, other):
+        return operator.ge(self.__key(), other.__key())
+
+    def __gt__(self, other):
+        return operator.gt(self.__key(), other.__key())
+
     def __str__(self):
-        pyspecs = set()
-        markerset = set()
-        for m in self.markerset:
-            marker_specs = pyspec_from_markers(packaging.markers.Marker(m))
-            if marker_specs:
-                pyspecs.add(marker_specs)
-            else:
-                markerset.add(m)
-        if pyspecs:
-            self.pyspecset._specs &= pyspecs
-            self.markerset = frozenset(markerset)
+        self.markerset = frozenset(filter(None, self.markerset))
         return " and ".join(dedup_markers(itertools.chain(
             # Make sure to always use the same quotes so we can dedup properly.
             (
                 "{0}".format(ms) if " or " in ms else ms
                 for ms in (str(m).replace('"', "'") for m in self.markerset)
+                if ms
             ),
             (
-                "python_version {0[0]} '{0[1]}'".format(spec)
-                for spec in cleanup_pyspecs(self.pyspecset)
-            ),
+                "{0}".format(str(self.pyspecset)) if self.pyspecset else "",
+            )
         )))
 
     def __bool__(self):
@@ -65,19 +87,38 @@ def __bool__(self):
     def __nonzero__(self):  # Python 2.
         return self.__bool__()
 
-    def __or__(self, pair):
+    @classmethod
+    def from_tuple(cls, pair):
         marker, specset = pair
-        markerset = set(self.markerset)
+        pyspecs = PySpecs(specset)
+        markerset = set()
         if marker:
-            marker_specs = pyspec_from_markers(marker)
-            if not marker_specs:
-                markerset.add(str(marker))
-            else:
-                specset._specs &= marker_specs
+            # Returns a PySpec instance or None
+            marker_pyversions = get_contained_pyversions(marker)
+            if marker_pyversions:
+                pyspecs.add(marker_pyversions)
+            # The remainder of the marker, if there is any
+            cleaned_marker = get_without_pyversion(marker)
+            if cleaned_marker:
+                markerset.add(str(cleaned_marker))
+        metaset = cls()
+        metaset.markerset = frozenset(markerset)
+        metaset.pyspecset = pyspecs
+        return metaset
+
+    def __or__(self, other):
+        if not isinstance(other, type(self)):
+            other = self.from_tuple(other)
         metaset = MetaSet()
+        markerset = set()
+        specset = PySpecs()
+        for meta in (self, other):
+            if meta.markerset:
+                markerset |= set(meta.markerset)
+            if meta.pyspecset:
+                specset = specset | meta.pyspecset
         metaset.markerset = frozenset(markerset)
-        # TODO: Implement some logic to clean up dups like '3.0.*' and '3.0'.
-        metaset.pyspecset &= self.pyspecset & specset
+        metaset.pyspecset = specset
         return metaset
 
 
@@ -91,19 +132,19 @@ def _build_metasets(dependencies, pythons, key, trace, all_metasets):
             return
         all_parent_metasets.append((parent, parent_metasets))
 
-    metaset_iters = []
+    metasets = set()
     for parent, parent_metasets in all_parent_metasets:
         r = dependencies[parent][key]
         python = pythons[key]
+        markers = None if r.editable else get_without_extra(r.markers)
         metaset = (
-            get_without_extra(r.markers),
+            markers,
             packaging.specifiers.SpecifierSet(python),
         )
-        metaset_iters.append(
-            parent_metaset | metaset
-            for parent_metaset in parent_metasets
-        )
-    return list(itertools.chain.from_iterable(metaset_iters))
+        for parent_metaset in parent_metasets:
+            child_metaset = parent_metaset | metaset
+            metasets.add(child_metaset)
+    return list(metasets)
 
 
 def _calculate_metasets_mapping(dependencies, pythons, traces):
@@ -117,7 +158,7 @@ def _calculate_metasets_mapping(dependencies, pythons, traces):
             metasets = _build_metasets(
                 dependencies, pythons, key, trace, all_metasets,
             )
-            if metasets is None:
+            if metasets is None or len(metasets) == 0:
                 continue
             new_metasets[key] = metasets
         if not new_metasets:
@@ -130,16 +171,17 @@ def _calculate_metasets_mapping(dependencies, pythons, traces):
 
 
 def _format_metasets(metasets):
-    # If there is an unconditional route, this needs to be unconditional.
-    if not metasets or not all(metasets):
-        return None
 
+    metasets = dedup_markers(metaset for metaset in metasets if metaset)
+    # If there is an unconditional route, this needs to be unconditional.
+    if not metasets:
+        return ""
+    combined_metaset = str(MetaSet() | reduce(lambda x, y: x | y, metasets))
+    if not combined_metaset:
+        return ""
     # This extra str(Marker()) call helps simplify the expression.
-    return str(packaging.markers.Marker(" or ".join(
-        "{0}".format(s) if " and " in s else s
-        for s in dedup_markers(str(metaset) for metaset in metasets
-        if metaset)
-    )))
+    metaset_string = str(packaging.markers.Marker(combined_metaset))
+    return metaset_string
 
 
 def set_metadata(candidates, traces, dependencies, pythons):
diff --git a/src/passa/internals/projects.py b/src/passa/models/projects.py
similarity index 99%
rename from src/passa/internals/projects.py
rename to src/passa/models/projects.py
index f6e037d..7ff6f31 100644
--- a/src/passa/internals/projects.py
+++ b/src/passa/models/projects.py
@@ -84,6 +84,7 @@ def dumps(self):
 class Project(object):
 
     root = attr.ib()
+    env_prefix = attr.ib(default=None)
     _p = attr.ib(init=False)
     _l = attr.ib(init=False)
 
diff --git a/src/passa/internals/providers.py b/src/passa/models/providers.py
similarity index 97%
rename from src/passa/internals/providers.py
rename to src/passa/models/providers.py
index bf4fd22..e62a031 100644
--- a/src/passa/internals/providers.py
+++ b/src/passa/models/providers.py
@@ -6,11 +6,12 @@
 
 import resolvelib
 
-from .candidates import find_candidates
-from .dependencies import get_dependencies
-from .utils import (
-    filter_sources, get_allow_prereleases,
-    are_requirements_equal, identify_requirment, strip_extras,
+from packagebuilder import filter_sources
+
+from ..internals.candidates import find_candidates
+from ..internals.dependencies import get_dependencies
+from ..internals.utils import (
+    get_allow_prereleases, identify_requirment, strip_extras,
 )
 
 
diff --git a/src/passa/operations/sync.py b/src/passa/operations/sync.py
deleted file mode 100644
index 3014e8d..0000000
--- a/src/passa/operations/sync.py
+++ /dev/null
@@ -1,23 +0,0 @@
-# -*- coding=utf-8 -*-
-
-from __future__ import absolute_import, print_function, unicode_literals
-
-
-def sync(syncer):
-    print("Starting synchronization")
-    installed, updated, cleaned = syncer.sync()
-    if cleaned:
-        print("Uninstalled: {}".format(", ".join(sorted(cleaned))))
-    if installed:
-        print("Installed: {}".format(", ".join(sorted(installed))))
-    if updated:
-        print("Updated: {}".format(", ".join(sorted(updated))))
-    return True
-
-
-def clean(cleaner):
-    print("Cleaning")
-    cleaned = cleaner.clean()
-    if cleaned:
-        print("Uninstalled: {}".format(", ".join(sorted(cleaned))))
-    return True
diff --git a/tasks/package.py b/tasks/package.py
index f229e3a..5ae379b 100644
--- a/tasks/package.py
+++ b/tasks/package.py
@@ -5,7 +5,8 @@
 import distlib.scripts
 import distlib.wheel
 import invoke
-import passa.internals._pip
+import packagebuilder
+import passa.models.caches
 import plette
 import requirementslib
 
@@ -75,8 +76,8 @@ def pack(ctx, remove_lib=True):
         package.pop('editable', None)   # Don't install things as editable.
         package.pop('markers', None)    # Always install everything.
         r = requirementslib.Requirement.from_pipfile(name, package)
-        wheel = passa.internals._pip.build_wheel(
-            r.as_ireq(), sources, r.hashes or None,
+        wheel = packagebuilder._pip.build_wheel(
+            r.as_ireq(), sources, r.hashes or None, cache_dir=passa.models.caches.CACHE_DIR
         )
         wheel.install(paths, maker, lib_only=True)
 
diff --git a/tests/actions/__init__.py b/tests/actions/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/actions/test_add.py b/tests/actions/test_add.py
new file mode 100644
index 0000000..e7cd883
--- /dev/null
+++ b/tests/actions/test_add.py
@@ -0,0 +1,20 @@
+# -*- coding=utf-8 -*-
+import passa.actions.init
+import passa.actions.add
+import passa.cli.options
+import passa.models.projects
+
+
+def test_add_one(project_directory):
+    project = passa.cli.options.Project(project_directory.strpath)
+    retcode = passa.actions.add.add_packages(["pytz"], project=project)
+    assert not retcode
+    assert 'pytz' in project.lockfile.default
+
+
+def test_add_one_with_deps(project_directory):
+    project = passa.cli.options.Project(project_directory.strpath)
+    retcode = passa.actions.add.add_packages(["requests"], project=project)
+    assert not retcode
+    assert 'requests' in project.lockfile.default
+    assert 'idna' in project.lockfile.default
diff --git a/tests/actions/test_clean.py b/tests/actions/test_clean.py
new file mode 100644
index 0000000..c56d06d
--- /dev/null
+++ b/tests/actions/test_clean.py
@@ -0,0 +1,18 @@
+# -*- coding=utf-8 -*-
+import passa.actions.add
+import passa.actions.clean
+
+
+def test_clean_subset(project):
+    retcode = passa.actions.add.add_packages(["requests"], project=project)
+    assert not retcode
+    packages = ["requests", "chardet", "certifi", "idna"]
+    c = project.venv.run("pip install pytz")
+    assert c.returncode == 0
+    c = project.venv.run("python -c 'import pytz'")
+    assert c.returncode == 0
+    clean_retcode = passa.actions.clean.clean(project=project)
+    assert not clean_retcode
+    c = project.venv.run("python -c 'import pytz'")
+    assert c.returncode != 0
+    assert all(pkg in project.lockfile.default for pkg in packages)
diff --git a/tests/actions/test_freeze.py b/tests/actions/test_freeze.py
new file mode 100644
index 0000000..53d34f9
--- /dev/null
+++ b/tests/actions/test_freeze.py
@@ -0,0 +1,21 @@
+# -*- coding=utf-8 -*-
+import passa.actions.add
+import passa.actions.freeze
+import passa.cli.options
+import passa.models.projects
+
+
+def test_freeze(project_directory):
+    project = passa.cli.options.Project(project_directory.strpath)
+    retcode = passa.actions.add.add_packages(["requests"], project=project)
+    assert not retcode
+    packages = ["requests", "chardet", "certifi", "idna"]
+    assert all(pkg in project.lockfile.default for pkg in packages)
+    freeze_file = project_directory.join("requirements.txt")
+    freeze_retcode = passa.actions.freeze.freeze(
+        project=project, include_hashes=False, target=freeze_file.strpath
+    )
+    assert not freeze_retcode
+    lines = [line.strip() for line in freeze_file.readlines() if line.strip() != '']
+    for pkg in packages:
+        assert any(line.startswith(pkg) for line in lines)
diff --git a/tests/actions/test_init.py b/tests/actions/test_init.py
new file mode 100644
index 0000000..2f12530
--- /dev/null
+++ b/tests/actions/test_init.py
@@ -0,0 +1,19 @@
+# -*- coding=utf-8 -*-
+
+import pytest
+
+import passa.actions.init
+import passa.cli.options
+
+
+def test_init(tmpdir):
+    init_retcode = passa.actions.init.init_project(root=tmpdir.strpath)
+    assert init_retcode == 0
+    project = passa.cli.options.Project(tmpdir.strpath)
+    assert project.pipfile.packages._data == {}
+    assert project.pipfile.dev_packages._data == {}
+
+
+def test_init_exists(project_directory):
+    with pytest.raises(RuntimeError, match=r'.* is already a Pipfile project'):
+        passa.actions.init.init_project(root=project_directory.strpath)
diff --git a/tests/actions/test_install.py b/tests/actions/test_install.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/actions/test_lock.py b/tests/actions/test_lock.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/actions/test_remove.py b/tests/actions/test_remove.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/actions/test_sync.py b/tests/actions/test_sync.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/actions/test_upgrade.py b/tests/actions/test_upgrade.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/cli/__init__.py b/tests/cli/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/cli/test_add.py b/tests/cli/test_add.py
new file mode 100644
index 0000000..a6bcbda
--- /dev/null
+++ b/tests/cli/test_add.py
@@ -0,0 +1 @@
+# -*- coding=utf-8 -*-
diff --git a/tests/cli/test_clean.py b/tests/cli/test_clean.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/cli/test_freeze.py b/tests/cli/test_freeze.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/cli/test_init.py b/tests/cli/test_init.py
new file mode 100644
index 0000000..a6bcbda
--- /dev/null
+++ b/tests/cli/test_init.py
@@ -0,0 +1 @@
+# -*- coding=utf-8 -*-
diff --git a/tests/cli/test_install.py b/tests/cli/test_install.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/cli/test_lock.py b/tests/cli/test_lock.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/cli/test_remove.py b/tests/cli/test_remove.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/cli/test_sync.py b/tests/cli/test_sync.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/cli/test_upgrade.py b/tests/cli/test_upgrade.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..0b490de
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,64 @@
+# -*- coding=utf-8 -*-
+import os
+import pytest
+import passa
+import passa.cli.options
+import mork.virtualenv
+import pkg_resources
+import sys
+import vistir
+
+
+DEFAULT_PIPFILE_CONTENTS = """
+[[source]]
+name = "pypi"
+url = "https://pypi.org/simple"
+verify_ssl = true
+
+[packages]
+
+[dev-packages]
+""".strip()
+
+
+BASE_WORKING_SET = pkg_resources.WorkingSet(entries=sys.path)
+
+
+@pytest.fixture(scope="function")
+def project_directory(tmpdir_factory):
+    project_dir = tmpdir_factory.mktemp("passa-project")
+    project_dir.join("Pipfile").write(DEFAULT_PIPFILE_CONTENTS)
+    with vistir.contextmanagers.cd(project_dir.strpath):
+        yield project_dir
+
+
+@pytest.fixture(scope="function")
+def virtualenv(tmpdir_factory):
+    venv_dir = tmpdir_factory.mktemp("passa-testenv")
+    print("Creating virtualenv {0!r}".format(venv_dir.strpath))
+    c = vistir.misc.run([sys.executable, "-m", "virtualenv", venv_dir.strpath],
+                            return_object=True, block=True, nospin=True)
+    if c.returncode == 0:
+        print("Virtualenv created...")
+        return venv_dir
+    raise RuntimeError("Failed creating virtualenv for testing...{0!r}".format(c.err.strip()))
+
+
+class _Project(passa.cli.options.Project):
+    def __init__(self, root, venv=None):
+        self.path = root.strpath
+        self.venv = venv
+        super(_Project, self).__init__(self.path)
+
+
+@pytest.fixture
+def tmpvenv(virtualenv):
+    return mork.virtualenv.VirtualEnv(virtualenv.strpath)
+
+
+@pytest.fixture(scope="function")
+def project(project_directory, tmpvenv):
+    passa_dist = BASE_WORKING_SET.by_key["passa"]
+    resolved = tmpvenv.resolve_dist(passa_dist, BASE_WORKING_SET)
+    with tmpvenv.activated(extra_dists=list(resolved)):
+        yield _Project(project_directory, tmpvenv)
diff --git a/tests/integration/__init__.py b/tests/integration/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tox.ini b/tox.ini
index 2bc8e1d..d909724 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,7 +8,7 @@ setenv =
     LC_ALL = en_US.UTF-8
 deps =
 	coverage
-	-e .[tests]
+	-e .[virtualenv,tests]
 commands = coverage run --parallel -m pytest --timeout 300 []
 install_command = python -m pip install {opts} {packages}
 usedevelop = True
@@ -23,7 +23,7 @@ commands =
 [testenv:docs]
 deps =
     -r{toxinidir}/docs/requirements.txt
-    -e .[tests]
+    -e .[virtualenv,tests]
 commands =
     sphinx-build -d {envtmpdir}/doctrees -b html docs docs/build/html
     sphinx-build -d {envtmpdir}/doctrees -b man  docs docs/build/man