feat: Add line numbers with color-coded display and toggle option

gtm

@@ -133,6 +133,9 @@ class AppState:
     # Line wrapping settings
     wrap_lines: bool = True
     
+    # Line numbers settings
+    show_line_numbers: bool = False
+    
     # Change navigation
     change_blocks: List[Tuple[int, int]] = field(default_factory=list)  # (start_line, end_line) of each change block
     current_change_idx: int = -1  # -1 means no change is selected
@@ -356,6 +359,18 @@ def jump_to_prev_change(state: AppState) -> AppState:
 def draw_right_pane(stdscr, state):
     # If sidebar is hidden, right pane starts at column 0
     right_start = 0 if not state.show_sidebar else state.divider_col + 2
+    
+    # Calculate line number width if enabled
+    line_num_width = 0
+    if state.show_line_numbers:
+        # Width based on the number of digits in the largest line number
+        max_line_num = len(state.file_lines)
+        line_num_width = len(str(max_line_num)) + 1  # +1 for spacing
+    
+    # Adjust right pane start position and width for line numbers
+    if state.show_line_numbers:
+        right_start += line_num_width
+    
     right_width = state.width - right_start - 1
     
     max_scroll = max(0, len(state.file_lines) - (state.height - 1))
@@ -375,7 +390,8 @@ def draw_right_pane(stdscr, state):
         line_num = i + state.right_scroll_offset + 1
         if (state.show_whole_diff or state.show_deletions) and line_num in deleted_line_map:
             for del_content in deleted_line_map[line_num]:
-                display_lines.append({'type': 'deleted', 'content': del_content})
+                # For deleted lines, use the same line number
+                display_lines.append({'type': 'deleted', 'content': del_content, 'line_num': line_num})
         
         is_added = False
         if state.show_whole_diff or state.show_additions:
@@ -384,7 +400,7 @@ def draw_right_pane(stdscr, state):
                     is_added = True
                     break
         
-        display_lines.append({'type': 'added' if is_added else 'regular', 'content': line})
+        display_lines.append({'type': 'added' if is_added else 'regular', 'content': line, 'line_num': line_num})
 
     display_row = 0
     for line_info in display_lines:
@@ -393,6 +409,20 @@ def draw_right_pane(stdscr, state):
         
         line_type = line_info['type']
         content = line_info['content']
+        line_num = line_info.get('line_num', 0)
+        
+        # Draw line number if enabled
+        if state.show_line_numbers:
+            line_num_str = str(line_num).rjust(line_num_width - 1) + " "
+            line_num_pos = (0 if not state.show_sidebar else state.divider_col + 2)
+            
+            # Use different color for line numbers
+            if line_type == 'added':
+                stdscr.addstr(display_row, line_num_pos, line_num_str, curses.color_pair(5))
+            elif line_type == 'deleted':
+                stdscr.addstr(display_row, line_num_pos, line_num_str, curses.color_pair(6))
+            else:
+                stdscr.addstr(display_row, line_num_pos, line_num_str, curses.color_pair(7))
         
         # Determine prefix based on line type and diff mode
         prefix = ""
@@ -528,13 +558,14 @@ def draw_status_bars(stdscr, state):
         if len(parts) >= 4:
             commit_message = parts[3]
     
-    # Add wrap indicator and change position to commit message
+    # Add indicators to commit message
     wrap_indicator = "" if state.wrap_lines else "[NW] "
+    line_num_indicator = "[LN] " if state.show_line_numbers else ""
     change_indicator = ""
     if state.change_blocks and state.current_change_idx != -1:
         change_indicator = f"[Change {state.current_change_idx + 1}/{len(state.change_blocks)}] "
     
-    commit_message = wrap_indicator + change_indicator + commit_message
+    commit_message = wrap_indicator + line_num_indicator + change_indicator + commit_message
     
     # Status bar percentages
     if len(state.file_lines) > 0:
@@ -814,6 +845,8 @@ def handle_keyboard_input(key, state: AppState) -> AppState:
         return toggle_sidebar(state)
     elif key == ord('w'):
         return replace(state, wrap_lines=not state.wrap_lines)
+    elif key == ord('L'):  # Capital L to toggle line numbers
+        return replace(state, show_line_numbers=not state.show_line_numbers)
     elif key in [110, ord('n')]:  # ASCII code for 'n'
         if state.show_whole_diff or state.show_additions or state.show_deletions:
             return jump_to_next_change(state)
@@ -864,6 +897,9 @@ def main(stdscr, filename, show_diff, show_add, show_del, mouse, wrap_lines=True
         curses.init_pair(2, curses.COLOR_WHITE, 0)  # Inactive pane: white on black
         curses.init_pair(3, curses.COLOR_GREEN, -1)  # Added lines
         curses.init_pair(4, curses.COLOR_RED, -1)    # Deleted lines
+        curses.init_pair(5, curses.COLOR_GREEN, -1)  # Line numbers for added lines
+        curses.init_pair(6, curses.COLOR_RED, -1)    # Line numbers for deleted lines
+        curses.init_pair(7, curses.COLOR_BLUE, -1)   # Regular line numbers
 
     height, width = stdscr.getmaxyx()
     state = AppState(
@@ -930,6 +966,7 @@ if __name__ == "__main__":
     parser.add_argument("--diff-deletions", action="store_true", help="Show deleted lines in red")
     parser.add_argument("--no-mouse", action="store_true", help="Disable mouse support")
     parser.add_argument("--no-wrap", action="store_true", help="Disable line wrapping")
+    parser.add_argument("--line-numbers", action="store_true", help="Show line numbers")
     parser.add_argument("-v", "--version", action="store_true", help="Show version number")
     parser.add_argument("filename", nargs="?", help="File to view history for")
     
@@ -956,4 +993,4 @@ if __name__ == "__main__":
         print(f"  git commit -m 'Add {os.path.basename(filename)}'")
         sys.exit(1)
         
-    curses.wrapper(main, filename, args.diff, args.diff_additions, args.diff_deletions, not args.no_mouse, not args.no_wrap)
+    curses.wrapper(main, filename, args.diff, args.diff_additions, args.diff_deletions, not args.no_mouse, not args.no_wrap, args.line_numbers)