"""Main entry point for the Lichess bot."""

import argparse
import contextlib
import datetime
import json
import logging
import os
from pathlib import Path
import subprocess
import sys
import threading

import chess
import chess.pgn
import requests

from python_pkg.lichess_bot.engine import RandomEngine
from python_pkg.lichess_bot.lichess_api import LichessAPI
from python_pkg.lichess_bot.utils import backoff_sleep, get_and_increment_version

_logger = logging.getLogger(__name__)


def _apply_move_to_board(board: chess.Board, move: str, game_id: str) -> None:
    """Apply a single move to the board, logging errors.

    Args:
        board: The chess board to apply the move to.
        move: The UCI move string.
        game_id: The game ID for logging purposes.
    """
    try:
        board.push_uci(move)
    except ValueError:
        _logger.debug(f"Game {game_id}: could not apply move {move}")


def run_bot(log_level: str = "INFO", *, decline_correspondence: bool = False) -> None:
    """Start the bot and listen for incoming events."""
    # Configure root logger for console output
    logging.basicConfig(
        level=getattr(logging, log_level.upper(), logging.INFO),
        format="[%(asctime)s] %(levelname)s %(threadName)s: %(message)s",
    )

    token = os.getenv("LICHESS_TOKEN")
    if not token:
        msg = "LICHESS_TOKEN environment variable is required"
        raise RuntimeError(msg)

    _logger.info("Token present. Initializing client and engine...")
    # Self-incrementing bot version (persisted on disk)
    bot_version = get_and_increment_version()
    _logger.info(f"Bot version: v{bot_version}")
    api = LichessAPI(token)
    engine = RandomEngine()

    game_threads = {}

    def handle_game(game_id: str, my_color: str | None = None) -> None:
        _logger.info(f"Starting game thread for {game_id} [bot v{bot_version}]")
        board = chess.Board()
        color: str | None = my_color
        # Track how many moves we have already processed;
        # start at -1 so we act on the first state (0 moves)
        last_handled_len = -1
        # Prepare a per-game log file
        game_log_path = Path.cwd() / f"lichess_bot_game_{game_id}.log"
        try:
            with open(game_log_path, "w") as lf:
                lf.write(f"game {game_id} started\n")
                lf.write(f"bot_version v{bot_version}\n")
        except OSError:
            game_log_path = None
        # Simple time manager state
        my_ms = None
        opp_ms = None
        inc_ms = 0
        # Meta info for logging/PGN
        game_date_iso: str | None = None
        white_name: str | None = None
        black_name: str | None = None
        site_url: str | None = None
        try:
            # Only send moves on authoritative gameState events to avoid race
            # conditions right after gameFull arrives.
            for event in api.stream_game_events(game_id):
                et = event.get("type")
                if et in ("gameFull", "gameState"):
                    # Determine moves list and optional status
                    if et == "gameFull":
                        state = event.get("state", {})
                        moves = state.get("moves", "")
                        status = state.get("status")
                        # clocks are in milliseconds if present
                        my_ms = (
                            state.get("wtime")
                            if color == "white"
                            else state.get("btime")
                        )
                        opp_ms = (
                            state.get("btime")
                            if color == "white"
                            else state.get("wtime")
                        )
                        inc_ms = state.get("winc") or state.get("binc") or 0
                        # Discover my color from gameFull
                        white_id = event["white"].get("id")
                        black_id = event["black"].get("id")
                        white_name = event["white"].get("name") or white_id or "?"
                        black_name = event["black"].get("name") or black_id or "?"
                        # Set site and date if available
                        with contextlib.suppress(Exception):
                            # Lichess event may include 'createdAt' ms epoch
                            created_ms = event.get("createdAt") or event.get(
                                "createdAtDate"
                            )
                            if created_ms:
                                game_date_iso = datetime.datetime.fromtimestamp(
                                    int(created_ms) / 1000, tz=datetime.timezone.utc
                                ).strftime("%Y.%m.%d")
                        site_url = f"https://lichess.org/{game_id}"
                        me = api.get_my_user_id()
                        if me == white_id:
                            color = "white"
                        elif me == black_id:
                            color = "black"
                        _logger.info(f"Game {game_id}: joined as {color} (gameFull)")
                    else:
                        moves = event.get("moves", "")
                        status = event.get("status")
                        # update clocks from gameState if present
                        if color == "white":
                            my_ms = event.get("wtime", my_ms)
                            opp_ms = event.get("btime", opp_ms)
                            inc_ms = event.get("winc", inc_ms)
                        elif color == "black":
                            my_ms = event.get("btime", my_ms)
                            opp_ms = event.get("wtime", opp_ms)
                            inc_ms = event.get("binc", inc_ms)

                    moves_list = moves.split() if moves else []
                    new_len = len(moves_list)
                    _logger.info(
                        f"Game {game_id}: event={et}, moves={new_len}, color={color}"
                    )
                    if new_len == last_handled_len:
                        _logger.debug(
                            f"Game {game_id}: position unchanged "
                            f"(len={new_len}), skipping"
                        )
                        continue

                    # Rebuild board from moves
                    board = chess.Board()
                    for m in moves_list:
                        _apply_move_to_board(board, m, game_id)

                    if color is None:
                        _logger.info(
                            f"Game {game_id}: color unknown yet; waiting for gameFull"
                        )
                        # Do not mark this position handled on gameFull;
                        # wait for authoritative gameState
                        if et == "gameState":
                            last_handled_len = new_len
                        continue

                    is_white_turn = board.turn
                    my_turn = (is_white_turn and color == "white") or (
                        (not is_white_turn) and color == "black"
                    )
                    _logger.info(
                        f"Game {game_id}: "
                        f"turn={'white' if is_white_turn else 'black'}, "
                        f"my_turn={my_turn}"
                    )
                    # Move policy:
                    # - Always move on 'gameState' (authoritative)
                    # - Also allow moving on the initial 'gameFull' when there are
                    #   zero moves and it's our turn. This avoids stalling at game
                    #   start when Lichess doesn't immediately send a 'gameState'
                    #   for 0 moves.
                    allow_move = (et == "gameState") or (
                        et == "gameFull" and new_len == 0
                    )
                    if my_turn and allow_move:
                        # Compute a per-move time budget (seconds) based on
                        # remaining time.
                        # Heuristic: use min( max_time_sec,
                        #   max(0.05, 0.6 * my_time_left/remaining_moves + inc) )
                        # Estimate remaining moves as 30 - ply/2 bounded to [10, 60]
                        est_moves_left = max(
                            10, min(60, 30 - board.fullmove_number // 2)
                        )
                        time_left_sec = (my_ms or 0) / 1000.0
                        inc_sec = (inc_ms or 0) / 1000.0
                        budget = (
                            0.6 * (time_left_sec / max(1, est_moves_left))
                            + 0.5 * inc_sec
                        )
                        # Spend more time per move (requested): double the budget
                        budget *= 2.0
                        # Keep within reasonable bounds
                        budget = max(0.05, min(engine.max_time_sec, budget))
                        move, reason = engine.choose_move_with_explanation(
                            board, time_budget_sec=budget
                        )
                        if move is None:
                            _logger.info(
                                f"Game {game_id}: no legal moves (game likely over)"
                            )
                            break
                        try:
                            # Double-check legality just before sending
                            # to avoid 400s when state changed.
                            if move not in board.legal_moves:
                                _logger.info(
                                    f"Game {game_id}: selected move "
                                    "no longer legal; skipping send"
                                )
                            else:
                                _logger.info(
                                    f"Game {game_id}: playing {move.uci()} "
                                    f"(budget={budget:.2f}s, "
                                    f"my_time_left={time_left_sec:.1f}s, "
                                    f"inc={inc_sec:.2f}s)"
                                )
                                if game_log_path:
                                    with open(game_log_path, "a") as lf:
                                        lf.write(
                                            f"ply {last_handled_len + 1}: "
                                            f"{move.uci()}\n{reason}\n\n"
                                        )
                                api.make_move(game_id, move)
                        except requests.RequestException as e:
                            _logger.warning(
                                f"Game {game_id}: move {move.uci()} failed: {e}"
                            )
                    # Mark this position as handled on authoritative
                    # gameState, or after we've actually attempted a move
                    # (including the first move on gameFull len=0).
                    if et == "gameState" or (my_turn and allow_move):
                        last_handled_len = new_len
                    if status in {"mate", "resign", "stalemate", "timeout", "draw"}:
                        _logger.info(f"Game {game_id} finished: {status}")
                        break
                elif et in {"chatLine", "opponentGone"}:
                    continue
        except requests.RequestException:
            _logger.exception(f"Game {game_id} thread error")
        finally:
            # On game end, write full PGN to the log file
            try:
                if game_log_path:
                    game = chess.pgn.Game.from_board(board)
                    # Record the bot version in the PGN headers
                    with contextlib.suppress(Exception):
                        game.headers["BotVersion"] = f"v{bot_version}"
                        if site_url:
                            game.headers["Site"] = site_url
                        if game_date_iso:
                            game.headers["Date"] = game_date_iso
                        if white_name:
                            game.headers["White"] = white_name
                        if black_name:
                            game.headers["Black"] = black_name
                    with open(game_log_path, "a") as lf:
                        lf.write("\nPGN:\n")
                        exporter = chess.pgn.StringExporter(
                            headers=True, variations=False, comments=False
                        )
                        lf.write(game.accept(exporter))
                        lf.write("\n")
                # After PGN is written, run analysis and save it
                # to the same file (inserted before PGN)
                if game_log_path:
                    analysis_text: str | None = None
                    try:
                        analyze_script = (
                            Path(__file__).resolve().parent.parent
                            / "stockfish_analysis"
                            / "analyze_chess_game.py"
                        )
                        if analyze_script.is_file():
                            # Estimate total plies from the final board
                            try:
                                total_plies = len(board.move_stack)
                            except TypeError:
                                total_plies = 0

                            _logger.info(
                                f"Game {game_id}: starting post-game "
                                f"analysis ({total_plies} plies)"
                            )
                            # Run analyzer unbuffered and stream output for progress
                            proc = subprocess.Popen(
                                [sys.executable, "-u", analyze_script, game_log_path],
                                stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE,
                                text=True,
                                bufsize=1,
                            )
                            analyzed = 0
                            lines: list[str] = []
                            ply_line_re = __import__("re").compile(r"^\s*(\d+)\s")
                            # Read stdout line by line
                            # stdout/stderr are guaranteed non-None with PIPE
                            assert proc.stdout is not None  # noqa: S101
                            assert proc.stderr is not None  # noqa: S101
                            for line in proc.stdout:
                                lines.append(line)
                                m = ply_line_re.match(line)
                                if m:
                                    # Count as one analyzed ply
                                    analyzed += 1
                                    left = (
                                        max(0, (total_plies or 0) - analyzed)
                                        if total_plies
                                        else "?"
                                    )
                                    if total_plies:
                                        pct = analyzed / total_plies * 100.0
                                        _logger.info(
                                            f"Game {game_id}: analysis progress "
                                            f"{analyzed}/{total_plies} "
                                            f"({pct:.0f}%), left {left}"
                                        )
                                    else:
                                        _logger.info(
                                            f"Game {game_id}: analysis progress "
                                            f"{analyzed} plies (total unknown)"
                                        )

                            # Capture any remaining stderr and ensure process ends
                            stderr_text = proc.stderr.read() or ""
                            ret = proc.wait()
                            analysis_text = "".join(lines)
                            if ret != 0:
                                _logger.warning(
                                    f"Game {game_id}: analysis script "
                                    f"exited with code {ret}"
                                )
                                if stderr_text:
                                    analysis_text += "\n[stderr]\n" + stderr_text
                            _logger.info(f"Game {game_id}: analysis complete")
                        else:
                            _logger.info(
                                f"Game {game_id}: analysis script not found "
                                f"at {analyze_script}; skipping analysis"
                            )
                    except (subprocess.SubprocessError, OSError) as e:
                        _logger.debug(f"Game {game_id}: analysis run failed: {e}")

                    # Insert analysis before the PGN section so future runs
                    # can still parse PGN cleanly
                    if analysis_text:
                        try:
                            with open(
                                game_log_path, encoding="utf-8", errors="replace"
                            ) as f:
                                content = f.read()

                            # Find the start of the 'PGN:' line
                            insert_idx = 0
                            p = content.find("\nPGN:\n")
                            if p != -1:
                                insert_idx = (
                                    p + 1
                                )  # start of the line after the preceding newline
                            elif content.startswith("PGN:\n"):
                                insert_idx = 0
                            else:
                                # If PGN marker not found (unexpected), append at end
                                insert_idx = len(content)

                            # Prepend meta information block for easier parsing later
                            meta_lines = []
                            if game_date_iso:
                                meta_lines.append(f"Date: {game_date_iso}")
                            if white_name or black_name:
                                meta_lines.append(
                                    f"Players: {white_name or '?'} "
                                    f"vs {black_name or '?'}"
                                )
                            if meta_lines:
                                meta_block = "\n".join(meta_lines) + "\n"
                            else:
                                meta_block = ""

                            analysis_block = (
                                (meta_block if meta_block else "")
                                + "ANALYSIS:\n"
                                + analysis_text.rstrip()
                                + "\n\n"
                            )
                            new_content = (
                                content[:insert_idx]
                                + analysis_block
                                + content[insert_idx:]
                            )
                            with open(game_log_path, "w", encoding="utf-8") as f:
                                f.write(new_content)
                        except OSError as e:
                            _logger.debug(
                                f"Game {game_id}: could not write analysis to log: {e}"
                            )
            except OSError as e:
                _logger.debug(f"Game {game_id}: could not write PGN: {e}")
            _logger.info(f"Ending game thread for {game_id}")

    def _process_event_stream() -> None:
        """Process events from the Lichess event stream.

        Handles challenges and game start/finish events.
        """
        for event in api.stream_events():
            if event.get("type") == "challenge":
                challenge = event["challenge"]
                ch_id = challenge["id"]
                variant = challenge.get("variant", {}).get("key", "standard")
                speed = challenge.get("speed")
                perf_ok = speed in {"bullet", "blitz", "rapid", "classical"}
                not_corr = (
                    challenge.get("speed") != "correspondence"
                    or not decline_correspondence
                )
                if variant == "standard" and perf_ok and not_corr:
                    _logger.info(f"Accepting challenge {ch_id} ({speed})")
                    api.accept_challenge(ch_id)
                else:
                    _logger.info(
                        f"Declining challenge {ch_id} "
                        f"(variant={variant}, speed={speed})"
                    )
                    api.decline_challenge(ch_id)

            elif event.get("type") == "gameStart":
                game_id = event["game"]["id"]
                # Spin up a game thread
                if game_id not in game_threads or not game_threads[game_id].is_alive():
                    t = threading.Thread(
                        target=handle_game, args=(game_id,), name=f"game-{game_id}"
                    )
                    t.daemon = True
                    game_threads[game_id] = t
                    t.start()

            elif event.get("type") == "gameFinish":
                game_id = event["game"]["id"]
                _logger.info(f"Game finished event: {game_id}")
            else:
                _logger.debug(f"Unhandled event: {json.dumps(event)}")

    def _run_event_loop_iteration() -> int:
        """Run one iteration of the event loop with error handling.

        Returns:
            New backoff value (0 on success, increased on error).
        """
        try:
            _process_event_stream()
        except requests.RequestException as e:
            _logger.warning(f"Event stream error: {e}")
            return backoff_sleep(backoff)
        else:
            # If stream ends normally, reset backoff
            return 0

    # Main event stream: challenge and game start events
    _logger.info("Connecting to Lichess event stream. Waiting for challenges...")
    backoff = 0
    while True:
        backoff = _run_event_loop_iteration()


def main() -> None:
    """Parse arguments and run the Lichess bot."""
    parser = argparse.ArgumentParser(description="Run a minimal Lichess bot")
    parser.add_argument(
        "--log-level", default="INFO", help="Logging level (default: INFO)"
    )
    parser.add_argument(
        "--decline-correspondence",
        action="store_true",
        help="Decline correspondence challenges",
    )
    args = parser.parse_args()
    run_bot(args.log_level, decline_correspondence=args.decline_correspondence)


if __name__ == "__main__":
    main()