git-time-machine/gtm2.py

#!/usr/bin/env python3

import curses
import os
import subprocess
import sys
import argparse

VERSION = "2025-06-07.3"

# --- Data Fetching & Utility Functions (Pure) ---

def get_commits(filename):
    cmd = ['git', 'log', '--pretty=format:%h %ad %s', '--date=format:%Y-%m-%d %H:%M', '--', filename]
    result = subprocess.run(cmd, capture_output=True, text=True)
    return result.stdout.splitlines()

def get_file_at_commit(commit_hash, filename):
    cmd = ['git', 'show', f'{commit_hash}:{filename}']
    result = subprocess.run(cmd, capture_output=True, text=True)
    return result.stdout.splitlines()

def find_best_matching_line(reference_line, file_lines, max_lines=None):
    """Find the best matching line in file_lines that matches reference_line.
    Returns the line index or None if no good match is found."""
    if not reference_line or not file_lines:
        return None
        
    # First try exact match
    for i, line in enumerate(file_lines):
        if line == reference_line:
            return i
            
    # If no exact match, try to find the most similar line
    # Only search through a reasonable number of lines for performance
    search_lines = file_lines[:max_lines] if max_lines else file_lines
    
    best_match = None
    best_score = 0
    
    for i, line in enumerate(search_lines):
        # Simple similarity score: count of common characters
        score = sum(1 for a, b in zip(reference_line, line) if a == b)
        
        # Adjust score based on length difference
        length_diff = abs(len(reference_line) - len(line))
        adjusted_score = score - (length_diff * 0.5)
        
        if adjusted_score > best_score:
            best_score = adjusted_score
            best_match = i
            
    # Only return a match if it's reasonably good
    # (at least 60% of the shorter string length)
    min_length = min(len(reference_line), 1)  # Avoid division by zero
    if best_score > (min_length * 0.6):
        return best_match
        
    return None

def get_diff_info(current_commit, prev_commit, filename):
    """Get diff information between two commits for a file"""
    if not prev_commit:
        return [], []
    
    cmd = ['git', 'diff', prev_commit, current_commit, '--', filename]
    result = subprocess.run(cmd, capture_output=True, text=True)
    
    lines = result.stdout.splitlines()
    added_lines = []
    deleted_lines = []
    current_line_num = 0
    i = 0
    while i < len(lines):
        line = lines[i]
        if line.startswith('@@'):
            parts = line.split()
            if len(parts) >= 3:
                add_part = parts[2][1:]
                if ',' in add_part:
                    current_line_num, _ = map(int, add_part.split(','))
                else:
                    current_line_num = int(add_part)
        elif line.startswith('+') and not line.startswith('+++'):
            added_lines.append((current_line_num, line[1:]))
            current_line_num += 1
        elif line.startswith('-') and not line.startswith('---'):
            deleted_lines.append((current_line_num, line[1:]))
        elif not line.startswith('+') and not line.startswith('-') and not line.startswith('@@'):
            current_line_num += 1
        i += 1
    return added_lines, deleted_lines

# --- Application State Class ---

class AppState:
    def __init__(self, filename, width, height, show_diff, show_add, show_del, mouse):
        self.filename = filename
        self.width = width
        self.height = height
        self.show_whole_diff = show_diff
        self.show_additions = show_add
        self.show_deletions = show_del
        self.enable_mouse = mouse

        self.commits = get_commits(filename)
        self.file_lines = []
        self.added_lines = []
        self.deleted_lines = []

        self.focus = "left"
        self.divider_col = 40
        
        self.selected_commit_idx = 0
        self.left_scroll_offset = 0
        self.right_scroll_offset = 0

        self.dragging_divider = False
        self.should_exit = False

        self.is_selecting = False
        self.selection_start_coord = None
        self.selection_end_coord = None
        self.click_position = None  # Store click position to detect clicks vs. drags
        self.last_bstate = 0
        self.mouse_x = -1
        self.mouse_y = -1

    def update_dimensions(self, height, width):
        self.height = height
        self.width = width

    def toggle_mouse(self):
        self.enable_mouse = not self.enable_mouse
        if self.enable_mouse:
            curses.mousemask(curses.ALL_MOUSE_EVENTS | curses.REPORT_MOUSE_POSITION)
        else:
            curses.mousemask(0)

    def move_commit_selection(self, delta):
        new_idx = self.selected_commit_idx + delta
        if 0 <= new_idx < len(self.commits):
            self.selected_commit_idx = new_idx
            self.load_commit_content()

    def page_commit_selection(self, direction):
        page_size = self.height - 1
        delta = page_size * direction
        self.move_commit_selection(delta)

    def scroll_right_pane(self, delta):
        max_scroll = max(0, len(self.file_lines) - (self.height - 1))
        new_offset = self.right_scroll_offset + delta
        self.right_scroll_offset = max(0, min(new_offset, max_scroll))

    def page_right_pane(self, direction):
        page_size = self.height - 1
        delta = page_size * direction
        self.scroll_right_pane(delta)

    def update_divider(self, mx):
        min_col = 10
        max_col = self.width - 20
        self.divider_col = max(min_col, min(mx, max_col))

    def load_commit_content(self):
        if not self.commits:
            return
        
        reference_line = None
        scroll_percentage = 0
        if len(self.file_lines) > 0:
            max_scroll_old = max(0, len(self.file_lines) - (self.height - 1))
            if max_scroll_old > 0:
                scroll_percentage = self.right_scroll_offset / max_scroll_old
            if self.right_scroll_offset < len(self.file_lines):
                reference_line = self.file_lines[self.right_scroll_offset]
        
        commit_hash = self.commits[self.selected_commit_idx].split()[0]
        self.file_lines = get_file_at_commit(commit_hash, self.filename)

        prev_commit_hash = None
        if self.selected_commit_idx < len(self.commits) - 1:
            prev_commit_hash = self.commits[self.selected_commit_idx + 1].split()[0]

        if self.show_whole_diff or self.show_additions or self.show_deletions:
            self.added_lines, self.deleted_lines = get_diff_info(commit_hash, prev_commit_hash, self.filename)
        else:
            self.added_lines, self.deleted_lines = [], []
        
        max_scroll_new = max(0, len(self.file_lines) - (self.height - 1))
        if reference_line:
            matching_line_idx = find_best_matching_line(reference_line, self.file_lines, 1000)
            if matching_line_idx is not None:
                self.right_scroll_offset = matching_line_idx
            else:
                self.right_scroll_offset = int(scroll_percentage * max_scroll_new)
        else:
            self.right_scroll_offset = int(scroll_percentage * max_scroll_new)
        
        self.right_scroll_offset = max(0, min(self.right_scroll_offset, max_scroll_new))

# --- Rendering Functions (View) ---

def draw_left_pane(stdscr, state):
    if state.selected_commit_idx < state.left_scroll_offset:
        state.left_scroll_offset = state.selected_commit_idx
    elif state.selected_commit_idx >= state.left_scroll_offset + state.height - 2:
        state.left_scroll_offset = state.selected_commit_idx - (state.height - 3)

    visible_commits = state.commits[state.left_scroll_offset:state.left_scroll_offset + state.height - 2]
    for i, line in enumerate(visible_commits):
        display_index = i + state.left_scroll_offset
        if display_index == state.selected_commit_idx:
            stdscr.attron(curses.A_REVERSE)
        stdscr.addnstr(i, 0, line, state.divider_col - 1)
        if display_index == state.selected_commit_idx:
            stdscr.attroff(curses.A_REVERSE)

def draw_right_pane(stdscr, state):
    right_width = state.width - state.divider_col - 3
    
    max_scroll = max(0, len(state.file_lines) - (state.height - 2))
    state.right_scroll_offset = min(state.right_scroll_offset, max_scroll)
    
    visible_lines = state.file_lines[state.right_scroll_offset:state.right_scroll_offset + state.height - 2]

    display_lines = []
    deleted_line_map = {}
    if state.show_whole_diff or state.show_deletions:
        for del_line_num, del_content in state.deleted_lines:
            if del_line_num not in deleted_line_map:
                deleted_line_map[del_line_num] = []
            deleted_line_map[del_line_num].append(del_content)

    for i, line in enumerate(visible_lines):
        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})
        
        is_added = False
        if state.show_whole_diff or state.show_additions:
            for added_line_num, _ in state.added_lines:
                if added_line_num == line_num:
                    is_added = True
                    break
        
        display_lines.append({'type': 'added' if is_added else 'regular', 'content': line})

    display_row = 0
    for line_info in display_lines:
        if display_row >= state.height - 2:
            break
        
        line_type = line_info['type']
        content = line_info['content']
        
        if line_type == 'added':
            stdscr.addstr(display_row, state.divider_col + 2, "+ ", curses.color_pair(3))
            stdscr.addnstr(display_row, state.divider_col + 4, content, right_width - 2, curses.color_pair(3))
        elif line_type == 'deleted':
            stdscr.addstr(display_row, state.divider_col + 2, "- ", curses.color_pair(4))
            stdscr.addnstr(display_row, state.divider_col + 4, content, right_width - 2, curses.color_pair(4))
        else:
            if state.show_whole_diff or state.show_additions or state.show_deletions:
                stdscr.addstr(display_row, state.divider_col + 2, "  ")
                stdscr.addnstr(display_row, state.divider_col + 4, content, right_width - 2)
            else:
                # No diff mode, so don't add the margin padding
                stdscr.addnstr(display_row, state.divider_col + 2, content, right_width)
        
        display_row += 1

def draw_divider(stdscr, state):
    divider_char = "║" if state.dragging_divider else "│"
    for y in range(state.height - 1):  # Don't draw through the commit message bar
        try:
            stdscr.addch(y, state.divider_col, divider_char)
        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
    
    # Determine pane from where selection started
    pane = 'left' if start_x < state.divider_col else 'right'
    if pane == 'left':
        pane_x1, pane_x2 = 0, state.divider_col - 1
    else: # right
        pane_x1, pane_x2 = state.divider_col + 2, state.width - 1

    # Determine drag direction to handle multi-line selection correctly
    if start_y < end_y or (start_y == end_y and start_x <= end_x):
        drag_start_x, drag_start_y = start_x, start_y
        drag_end_x, drag_end_y = end_x, end_y
    else: # upward drag or right-to-left on same line
        drag_start_x, drag_start_y = end_x, end_y
        drag_end_x, drag_end_y = start_x, start_y

    for y in range(drag_start_y, drag_end_y + 1):
        x1, x2 = -1, -1
        if drag_start_y == drag_end_y: # single line selection
            x1, x2 = drag_start_x, drag_end_x
        elif y == drag_start_y: # first line of multi-line selection
            x1, x2 = drag_start_x, pane_x2
        elif y == drag_end_y: # last line of multi-line selection
            x1, x2 = pane_x1, drag_end_x
        else: # middle line of multi-line selection
            x1, x2 = pane_x1, pane_x2
        
        # Clamp selection to pane boundaries
        x1 = max(x1, pane_x1)
        x2 = min(x2, pane_x2)

        try:
            if x1 < state.width and x1 <= x2:
                length = x2 - x1 + 1
                if length > 0:
                    stdscr.chgat(y, x1, length, curses.A_REVERSE)
        except curses.error:
            pass

def draw_status_bars(stdscr, state):
    # We'll use height-2 for the original status bars and height-1 for the commit message bar
    visible_height = state.height - 2
    
    # Get commit message for the selected commit
    commit_message = ""
    if state.commits and state.selected_commit_idx < len(state.commits):
        # Format is now: hash date time message
        # We need to split on more than just the first two spaces
        commit_line = state.commits[state.selected_commit_idx]
        parts = commit_line.split(' ', 3)  # Split into hash, date, time, message
        if len(parts) >= 4:
            commit_message = parts[3]
    
    # Status bar percentages
    if len(state.file_lines) > 0:
        last_visible_line = state.right_scroll_offset + visible_height
        right_percent = int((last_visible_line / len(state.file_lines)) * 100)
        right_percent = 100 if last_visible_line >= len(state.file_lines) else right_percent
    else:
        right_percent = 0
    right_status = f"{right_percent}% "
    
    if len(state.commits) > 0:
        last_visible_commit = state.left_scroll_offset + visible_height
        left_percent = int((last_visible_commit / len(state.commits)) * 100)
        left_percent = 100 if last_visible_commit >= len(state.commits) else left_percent
    else:
        left_percent = 0
    left_status = f"{left_percent}%"
    if state.enable_mouse:
        mouse_status = f" [M] {state.mouse_x},{state.mouse_y} b:{state.last_bstate}"
        if state.dragging_divider:
            mouse_status += " DIV"
        elif state.is_selecting:
            mouse_status += " SEL"
        left_status += mouse_status
    
    # Draw original status bars for left and right panes
    # Both active and inactive panes now use their respective color pairs
    left_attr = curses.color_pair(1) if state.focus == "left" else curses.color_pair(2)
    right_attr = curses.color_pair(1) if state.focus == "right" else curses.color_pair(2)
    
    # Fill the original status bar with spaces
    for x in range(state.divider_col):
        try:
            stdscr.addch(state.height - 2, x, ' ', left_attr)
        except curses.error:
            pass
    for x in range(state.divider_col + 1, state.width - 1):
        try:
            stdscr.addch(state.height - 2, x, ' ', right_attr)
        except curses.error:
            pass
    
    # Add percentage indicators on left and right sides of original status bar
    try:
        stdscr.addstr(state.height - 2, 1, left_status, left_attr)
    except curses.error:
        pass
        
    try:
        right_x = state.width - len(right_status) - 1
        if right_x >= 0:
            stdscr.addstr(state.height - 2, right_x, right_status, right_attr)
    except curses.error:
        pass
    
    # Draw divider in status bar
    try:
        stdscr.addch(state.height - 2, state.divider_col, "│")
    except curses.error:
        pass
    
    # Draw new full-width status bar with commit message below the original status bars
    status_attr = curses.color_pair(5)  # Color pair for commit message bar
    
    # Fill the commit message bar with spaces
    for x in range(state.width - 1):
        try:
            stdscr.addch(state.height - 1, x, ' ', status_attr)
        except curses.error:
            pass
    
    # Add commit message in the commit message bar
    if commit_message:
        max_msg_width = state.width - 4  # Leave a small margin
        if len(commit_message) > max_msg_width:
            commit_message = commit_message[:max_msg_width-3] + "..."
        
        try:
            stdscr.addstr(state.height - 1, 1, commit_message, status_attr)
        except curses.error:
            pass

def draw_ui(stdscr, state):
    stdscr.erase()
    draw_left_pane(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 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

    # Determine pane from where selection started
    pane = 'left' if start_x < state.divider_col else 'right'
    if pane == 'left':
        pane_x1, pane_x2 = 0, state.divider_col - 1
    else: # right
        pane_x1, pane_x2 = state.divider_col + 2, state.width - 1

    # Determine drag direction to handle multi-line selection correctly
    if start_y < end_y or (start_y == end_y and start_x <= end_x):
        drag_start_x, drag_start_y = start_x, start_y
        drag_end_x, drag_end_y = end_x, end_y
    else: # upward drag or right-to-left on same line
        drag_start_x, drag_start_y = end_x, end_y
        drag_end_x, drag_end_y = start_x, start_y

    height, width = stdscr.getmaxyx()
    selected_text_parts = []

    for y in range(drag_start_y, drag_end_y + 1):
        if not (0 <= y < height):
            continue

        x1, x2 = -1, -1
        if drag_start_y == drag_end_y: # single line selection
            x1, x2 = drag_start_x, drag_end_x
        elif y == drag_start_y: # first line of multi-line selection
            x1, x2 = drag_start_x, pane_x2
        elif y == drag_end_y: # last line of multi-line selection
            x1, x2 = pane_x1, drag_end_x
        else: # middle line of multi-line selection
            x1, x2 = pane_x1, pane_x2
        
        # Clamp selection to pane boundaries and screen width
        x1 = max(x1, pane_x1)
        x2 = min(x2, pane_x2, width - 1)

        line_str = ""
        if x1 <= x2:
            for x in range(x1, x2 + 1):
                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)

    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()
        state.last_bstate = bstate
        state.mouse_x, state.mouse_y = mx, my

        # Handle mouse button press
        if bstate & curses.BUTTON1_PRESSED:
            # Check if clicking near divider
            if abs(mx - state.divider_col) <= 1:
                state.dragging_divider = True
            else:
                # Switch panes immediately on click
                state.focus = "left" if mx < state.divider_col else "right"
                
                # Also start a potential selection (in case this becomes a drag)
                state.is_selecting = True
                state.selection_start_coord = (mx, my)
                state.selection_end_coord = (mx, my)
                state.click_position = (mx, my)
                
                # Redraw immediately to show selection highlight and focus change
                draw_ui(stdscr, state)
            return
            
        # Handle mouse button release
        if bstate & curses.BUTTON1_RELEASED:
            # End of divider drag
            if state.dragging_divider:
                state.dragging_divider = False
                return
                
            # End of selection
            if state.is_selecting:
                # Check if this was a click (press and release at same position)
                # or very close to the same position (within 1-2 pixels)
                if (state.click_position and 
                    abs(state.click_position[0] - mx) <= 2 and 
                    abs(state.click_position[1] - my) <= 2):
                    # This was a click, so switch panes
                    state.focus = "left" if mx < state.divider_col else "right"
                elif state.selection_start_coord and state.selection_end_coord:
                    # This was a drag selection, copy the text
                    copy_selection_to_clipboard(stdscr, state)
                
                # Reset selection state
                state.is_selecting = False
                state.selection_start_coord = None
                state.selection_end_coord = None
                state.click_position = None
                return
        
        # Handle mouse movement during drag operations
        if state.dragging_divider:
            # Update divider position during drag
            state.update_divider(mx)
        elif state.is_selecting:
            # Update selection end coordinates during drag
            state.selection_end_coord = (mx, my)
            # Redraw immediately to show selection highlight during drag
            draw_ui(stdscr, state)

    except curses.error:
        pass

def handle_keyboard_input(key, state):
    if key in [ord('q')]:
        state.should_exit = True
    elif key == 27:  # Escape key
        if state.is_selecting:
            state.is_selecting = False
            state.selection_start_coord = None
            state.selection_end_coord = None
        else:
            state.should_exit = True
    elif key == ord('m'):
        state.toggle_mouse()
    elif key in [curses.KEY_LEFT, ord('h')]:
        state.focus = "left"
    elif key in [curses.KEY_RIGHT, ord('l')]:
        state.focus = "right"
    
    elif state.focus == "left":
        if key in [curses.KEY_DOWN, ord('j')]:
            state.move_commit_selection(1)
        elif key in [curses.KEY_UP, ord('k')]:
            state.move_commit_selection(-1)
        elif key in [curses.KEY_NPAGE, ord(' ')]:
            state.page_commit_selection(1)
        elif key in [curses.KEY_PPAGE, 8, 127, curses.KEY_SR]:
            state.page_commit_selection(-1)

    elif state.focus == "right":
        if key in [curses.KEY_DOWN, ord('j')]:
            state.scroll_right_pane(1)
        elif key in [curses.KEY_UP, ord('k')]:
            state.scroll_right_pane(-1)
        elif key in [curses.KEY_NPAGE, ord(' ')]:
            state.page_right_pane(1)
        elif key in [curses.KEY_PPAGE, 8, 127, curses.KEY_SR]:
            state.page_right_pane(-1)

# --- Main Application ---

def main(stdscr, filename, show_diff, show_add, show_del, mouse):
    try:
        curses.curs_set(0)
    except:
        pass
    stdscr.keypad(True)
    stdscr.timeout(50)  # Less aggressive timeout (50ms instead of 10ms)

    if curses.has_colors():
        curses.use_default_colors()
        # Use a safe background color (7 or less) to avoid "Color number is greater than COLORS-1" error
        curses.init_pair(1, curses.COLOR_BLACK, 7)  # Active pane: black on white
        curses.init_pair(2, curses.COLOR_WHITE, 0)  # Inactive pane: white on black
        curses.init_pair(3, curses.COLOR_GREEN, -1)
        curses.init_pair(4, curses.COLOR_RED, -1)
        curses.init_pair(5, curses.COLOR_BLACK, 7)  # Status bar color (white background)

    height, width = stdscr.getmaxyx()
    state = AppState(filename, width, height, show_diff, show_add, show_del, mouse)
    
    if state.enable_mouse:
        curses.mousemask(curses.ALL_MOUSE_EVENTS | curses.REPORT_MOUSE_POSITION)
        # Enable mouse motion events for better drag tracking
        try:
            print("\033[?1003h", end="", flush=True)
        except:
            pass
    
    state.load_commit_content()
    
    # Initial draw before the main loop starts
    draw_ui(stdscr, state)

    while not state.should_exit:
        try:
            key = stdscr.getch()
            
            # Process input and update the application state
            if key == -1:  # No input available (timeout)
                pass  # Just redraw the UI and continue
            elif key == curses.KEY_RESIZE:
                h, w = stdscr.getmaxyx()
                state.update_dimensions(h, w)
            elif state.enable_mouse and key == curses.KEY_MOUSE:
                handle_mouse_input(stdscr, state)
            else:
                handle_keyboard_input(key, state)
            
            # After every action, redraw the UI to reflect changes immediately.
            # This is crucial for real-time feedback during mouse drags.
            draw_ui(stdscr, state)
        except Exception as e:
            # Prevent crashes by catching exceptions
            # Uncomment for debugging:
            # with open("/tmp/gtm_error.log", "a") as f:
            #     f.write(f"{str(e)}\n")
            pass
    
    # Disable mouse motion events when exiting
    if state.enable_mouse:
        try:
            print("\033[?1003l", end="", flush=True)
        except:
            pass

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="A \"Git Time Machine\" for viewing file history")
    parser.add_argument("-d", "--diff", action="store_true", help="Highlight newly added and deleted lines")
    parser.add_argument("--diff-additions", action="store_true", help="Highlight newly added lines in green")
    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("-v", "--version", action="store_true", help="Show version number")
    parser.add_argument("filename", nargs="?", help="File to view history for")
    
    args = parser.parse_args()
    
    if args.version:
        print(f"gtm version {VERSION}")
        sys.exit(0)
    elif not args.filename:
        parser.print_help()
        sys.exit(1)
    
    filename = args.filename
    
    if not os.path.isfile(filename):
        print(f"Error: File '{filename}' does not exist")
        sys.exit(1)
        
    curses.wrapper(main, filename, args.diff, args.diff_additions, args.diff_deletions, not args.no_mouse)