feat(vim): optional vim-style modal editing in the compose entry

README.md

@@ -499,6 +499,7 @@ This configuration file holds general user interface settings. Default content:
     typing_status_share=1
     undo_clear_input=1
     unread_indicator=*
+    vim_mode=0
 
 ### attachment_indicator
 
@@ -850,6 +851,33 @@ is enabled.
 
 Specifies the character to suffix chats with unread messages in the chat list.
 
+### vim_mode
+
+Specifies whether to enable vim-style modal editing in the message compose
+entry. Default `0` (disabled). When enabled, the entry starts in insert mode;
+press `Esc` for normal mode. The current mode is shown as a colored badge in
+the status bar (configurable via the `vim_*_color` / `vim_*_attr` keys in
+`color.conf`) and as a cursor shape (bar in insert, block in normal).
+
+Supported commands in normal mode:
+
+| Group | Commands |
+| ----- | -------- |
+| Motions | `h l 0 ^ $`, `w e b W E B`, `( )` (sentence), `{ }` (paragraph), `j k`, `gg G`, `f F t T` |
+| Operators | `d c y` + any motion; `dd cc yy` (line); `D C` (to end of line) |
+| Edit | `x X`, `s S` (substitute), `o O` (open line), `p P` (paste) |
+| Modes | `i a A I` (insert), `v` (visual), `Esc` (normal) |
+| Counts | e.g. `3w`, `d3w`, `2dd` |
+
+Visual mode (`v`) highlights the selection and applies `d c y x` to it.
+When `vim_mode=0` there is no behavioral change and zero overhead.
+
+### send_on_double_enter
+
+Set `send_on_double_enter=1` in `ui.conf` (default `0`) to make a single
+`Enter` insert a newline and a second consecutive `Enter` send the message
+(dropping the just-typed newline). The existing `send_msg` key still works.
+
 ~/.config/nchat/key.conf
 ------------------------
 This configuration file holds user interface key bindings. Default content:
@@ -986,6 +1014,16 @@ This configuration file holds user interface color settings. Default content:
     top_color_bg=
     top_color_fg=
 
+Vim mode badge colors (`vim_*_color_bg`, `vim_*_color_fg`, `vim_*_attr`):
+
+| Prefix | Default badge |
+| ------ | ------------- |
+| `vim_normal_*` | bright-blue bg / black fg (bold) |
+| `vim_insert_*` | bright-green bg / black fg (bold) |
+| `vim_visual_*` | bright-yellow bg / black fg (bold) |
+
+Conventional vim/airline mode colors. Configurable via `vim_normal_*` / `vim_insert_*` / `vim_visual_*` in `color.conf`.
+
 Supported text attributes `_attr` (defaults to `normal` if not specified):
 
     normal

src/ui.cpp

@@ -55,6 +55,7 @@ void Ui::Init()
   cbreak();
   UiConfig::GetBool("linefeed_on_enter") ? nl() : nonl();
   keypad(stdscr, TRUE);
+  set_escdelay(25); // minimize lag on bare ESC (vim_mode mode switch)
   curs_set(0);
   timeout(0);
   EmojiList::Init();

src/uicolorconfig.cpp

@@ -46,6 +46,16 @@ void UiColorConfig::Init()
     { "status_attr", "reverse" },
     { "status_color_bg", "" },
     { "status_color_fg", "" },
+    // Conventional vim/airline mode colors (NORMAL blue, INSERT green, VISUAL yellow).
+    { "vim_normal_attr", "bold" },
+    { "vim_normal_color_bg", "bright_blue" },
+    { "vim_normal_color_fg", "black" },
+    { "vim_insert_attr", "bold" },
+    { "vim_insert_color_bg", "bright_green" },
+    { "vim_insert_color_fg", "black" },
+    { "vim_visual_attr", "bold" },
+    { "vim_visual_color_bg", "bright_yellow" },
+    { "vim_visual_color_fg", "black" },
     { "list_attr", "" },
     { "list_attr_selected", "reverse" },
     { "list_color_bg", "" },

src/uiconfig.cpp

@@ -62,6 +62,7 @@ void UiConfig::Init()
     { "online_status_share", "1" },
     { "online_status_dynamic", "1" },
     { "phone_number_indicator", "" },
+    { "send_on_double_enter", "0" },
     { "pinned_indicator", "\xe2\x9a\xb2" },
     { "proxy_indicator", "\xF0\x9F\x94\x92" },
     { "read_indicator", "\xe2\x9c\x93" },
@@ -80,6 +81,7 @@ void UiConfig::Init()
     { "typing_status_share", "1" },
     { "undo_clear_input", "1" },
     { "unread_indicator", "*" },
+    { "vim_mode", "0" },
   };
 
   const std::string configPath(FileUtil::GetApplicationDir() + std::string("/ui.conf"));

src/uientryview.cpp

@@ -41,6 +41,28 @@ void UiEntryView::Draw()
   int cy = 0;
   lines = StrUtil::WordWrap(input, m_W, false, false, false, 2, inputPos, cy, cx);
 
+  // Vim visual selection: compute anchor screen coords + selection ordering
+  bool selActive = m_Model->GetVimModeLocked() && m_Model->GetVimVisualLocked();
+  int selStartY = 0, selStartX = 0, selEndY = 0, selEndX = 0;
+  if (selActive)
+  {
+    int ax = 0, ay = 0;
+    std::vector<int> dummyJunk; (void)dummyJunk;
+    int anchorPos = m_Model->GetVimVisualAnchorLocked();
+    int tcx = 0, tcy = 0;
+    StrUtil::WordWrap(input, m_W, false, false, false, 2, anchorPos, tcy, tcx);
+    ay = tcy; ax = tcx;
+    // order anchor vs cursor in reading order; selection is inclusive of both cells
+    if ((ay < cy) || ((ay == cy) && (ax <= cx)))
+    {
+      selStartY = ay; selStartX = ax; selEndY = cy; selEndX = cx;
+    }
+    else
+    {
+      selStartY = cy; selStartX = cx; selEndY = ay; selEndX = ax;
+    }
+  }
+
   static int colorPair = UiColorConfig::GetColorPair("entry_color");
   static int attribute = UiColorConfig::GetAttribute("entry_attr");
 
@@ -52,11 +74,29 @@ void UiEntryView::Draw()
 
   for (int i = 0; i < m_H; ++i)
   {
-    if ((i + yoffs) < (int)lines.size())
+    int lineIdx = i + yoffs;
+    if (lineIdx < (int)lines.size())
     {
-      line = lines.at(i + yoffs).c_str();
+      line = lines.at(lineIdx).c_str();
       line.erase(std::remove(line.begin(), line.end(), EMOJI_PAD), line.end());
       mvwaddwstr(m_Win, i, 0, line.c_str());
+
+      // Overdraw the selected span on this row with reverse video
+      if (selActive && (lineIdx >= selStartY) && (lineIdx <= selEndY))
+      {
+        int len = (int)line.size();
+        int a = (lineIdx == selStartY) ? selStartX : 0;
+        int b = (lineIdx == selEndY) ? selEndX : (len - 1);
+        a = std::max(0, std::min(a, len - 1));
+        b = std::max(0, std::min(b, len - 1));
+        if (len > 0 && b >= a)
+        {
+          std::wstring seg = line.substr(a, b - a + 1);
+          wattron(m_Win, attribute | colorPair | A_REVERSE);
+          mvwaddnwstr(m_Win, i, a, seg.c_str(), seg.size());
+          wattroff(m_Win, A_REVERSE);
+        }
+      }
     }
   }