feat: Implement mouse-based text selection and clipboard copying

gtm2.py

@@ -118,6 +118,10 @@ class AppState:
         self.dragging_divider = False
         self.should_exit = False
 
+        self.is_selecting = False
+        self.selection_start_coord = None
+        self.selection_end_coord = None
+
     def update_dimensions(self, height, width):
         self.height = height
         self.width = width
@@ -268,6 +272,28 @@ def draw_divider(stdscr, state):
         except curses.error:
             pass
 
+def draw_selection(stdscr, state):
+    if not state.is_selecting or not state.selection_start_coord:
+        return
+
+    start_x, start_y = state.selection_start_coord
+    end_x, end_y = state.selection_end_coord
+    
+    x1, x2 = min(start_x, end_x), max(start_x, end_x)
+    y1, y2 = min(start_y, end_y), max(start_y, end_y)
+
+    for y in range(y1, y2 + 1):
+        try:
+            # chgat can fail at the bottom-right corner of the screen
+            if x1 < state.width:
+                # `width-1` is the last valid column
+                end_col = min(x2, state.width - 1)
+                length = end_col - x1 + 1
+                if length > 0:
+                    stdscr.chgat(y, x1, length, curses.A_REVERSE)
+        except curses.error:
+            pass
+
 def draw_status_bars(stdscr, state):
     visible_height = state.height - 1
     
@@ -308,26 +334,76 @@ def draw_ui(stdscr, state):
     draw_right_pane(stdscr, state)
     draw_divider(stdscr, state)
     draw_status_bars(stdscr, state)
+    draw_selection(stdscr, state)
     stdscr.refresh()
 
 # --- Input Handling Functions (Controller) ---
 
-def handle_mouse_input(state):
+def copy_selection_to_clipboard(stdscr, state):
+    if not state.selection_start_coord or not state.selection_end_coord:
+        return
+
+    start_x, start_y = state.selection_start_coord
+    end_x, end_y = state.selection_end_coord
+
+    x1, x2 = min(start_x, end_x), max(start_x, end_x)
+    y1, y2 = min(start_y, end_y), max(start_y, end_y)
+
+    height, width = stdscr.getmaxyx()
+    selected_text_parts = []
+
+    for y in range(y1, y2 + 1):
+        if 0 <= y < height:
+            line_str = ""
+            for x in range(x1, x2 + 1):
+                if 0 <= x < width:
+                    try:
+                        char_and_attr = stdscr.inch(y, x)
+                        char = char_and_attr & 0xFF
+                        line_str += chr(char)
+                    except curses.error:
+                        line_str += " "
+            selected_text_parts.append(line_str.rstrip())
+
+    if selected_text_parts:
+        text_to_copy = "\n".join(selected_text_parts)
+        if text_to_copy.strip():
+            try:
+                subprocess.run(['pbcopy'], input=text_to_copy, text=True, check=True)
+            except (FileNotFoundError, subprocess.CalledProcessError):
+                pass
+
+def handle_mouse_input(stdscr, state):
     try:
         _, mx, my, _, bstate = curses.getmouse()
 
         if bstate & curses.BUTTON1_PRESSED:
             if abs(mx - state.divider_col) <= 1:
                 state.dragging_divider = True
+            else:
+                state.is_selecting = True
+                state.selection_start_coord = (mx, my)
+                state.selection_end_coord = (mx, my)
         
         if state.dragging_divider:
             state.update_divider(mx)
+        elif state.is_selecting:
+            state.selection_end_coord = (mx, my)
         
         if bstate & curses.BUTTON1_RELEASED:
             if state.dragging_divider:
                 state.dragging_divider = False
-            else:
+            elif state.is_selecting:
+                state.is_selecting = False
+                start_x, start_y = state.selection_start_coord
+                
+                if start_x == mx and start_y == my:
                     state.focus = "left" if mx < state.divider_col else "right"
+                else:
+                    copy_selection_to_clipboard(stdscr, state)
+                
+                state.selection_start_coord = None
+                state.selection_end_coord = None
     except curses.error:
         pass
 
@@ -397,7 +473,7 @@ def main(stdscr, filename, show_diff, show_add, show_del, mouse):
             continue
 
         if state.enable_mouse and key == curses.KEY_MOUSE:
-            handle_mouse_input(state)
+            handle_mouse_input(stdscr, state)
         else:
             handle_keyboard_input(key, state)