# by ChatGPT

import curses
import subprocess
import sys

def get_commits(filename):
    cmd = ['git', 'log', '--pretty=format:%h %ad %s', '--date=short', '--', 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 main(stdscr, filename):
    curses.curs_set(0)
    curses.mousemask(curses.ALL_MOUSE_EVENTS)
    stdscr.keypad(True)

    commits = get_commits(filename)
    selected_commit = 0
    divider_col = 40
    focus = "left"
    scroll_offset = 0

    while True:
        stdscr.clear()
        height, width = stdscr.getmaxyx()

        # Fetch file content for selected commit
        commit_hash = commits[selected_commit].split()[0]
        file_lines = get_file_at_commit(commit_hash, filename)
        max_scroll = max(0, len(file_lines) - (height - 1))
        scroll_offset = min(scroll_offset, max_scroll)
        visible_lines = file_lines[scroll_offset:scroll_offset + height - 1]

        # Draw commit list (left pane)
        for i in range(min(len(commits), height - 1)):
            line = commits[i]
            if i == selected_commit:
                stdscr.attron(curses.A_REVERSE)  # Highlight selected commit
            stdscr.addnstr(i, 0, line, divider_col - 1)
            if i == selected_commit:
                stdscr.attroff(curses.A_REVERSE)

        # Vertical divider
        for y in range(height):
            stdscr.addch(y, divider_col, '│')

        # Draw file content (right pane)
        for i, line in enumerate(visible_lines):
            stdscr.addnstr(i, divider_col + 2, line, width - divider_col - 3)

        # Status bar for right pane (line N/M)
        status = f"line {scroll_offset + 1}/{len(file_lines)}"
        stdscr.addnstr(height - 1, divider_col + 2, status, width - divider_col - 3, curses.A_DIM)

        stdscr.refresh()
        key = stdscr.getch()

        # Mouse click changes focus
        if key == curses.KEY_MOUSE:
            try:
                _, mx, my, _, bstate = curses.getmouse()
                if bstate & curses.BUTTON1_CLICKED:
                    focus = "left" if mx <= divider_col else "right"
            except curses.error:
                pass

        elif key in [ord('q'), 27]:
            break

        # Left pane movement
        elif focus == "left":
            if key in [curses.KEY_DOWN, ord('j')]:
                if selected_commit < len(commits) - 1:
                    selected_commit += 1
                    scroll_offset = 0
            elif key in [curses.KEY_UP, ord('k')]:
                if selected_commit > 0:
                    selected_commit -= 1
                    scroll_offset = 0

        # Right pane scrolling
        elif focus == "right":
            if key in [curses.KEY_DOWN, ord('j')]:
                if scroll_offset < max_scroll:
                    scroll_offset += 1
            elif key in [curses.KEY_UP, ord('k')]:
                if scroll_offset > 0:
                    scroll_offset -= 1
            elif key in [curses.KEY_NPAGE, ord(' ')]:
                scroll_offset = min(scroll_offset + height - 1, max_scroll)
            elif key in [curses.KEY_PPAGE, 8, 127]:  # Page Up or Shift+Space (some terminals)
                scroll_offset = max(0, scroll_offset - (height - 1))

        # Pane switching
        if key in [curses.KEY_LEFT, ord('h')]:
            focus = "left"
        elif key in [curses.KEY_RIGHT, ord('l')]:
            focus = "right"

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python git_time_machine.py path/to/file")
        sys.exit(1)
    filename = sys.argv[1]
    curses.wrapper(main, filename)