import time

import chess
import chess.svg
import chess.engine


class GameOver(Exception):
    pass


class IllegalMove(Exception):
    pass


class ChessSession:
    def __init__(self, engine):
        self.engine = engine
        self.board = chess.Board()

        self.ts = time.time()
        self.move_ts = time.time()

    def check_game_over(self):
        if self.board.is_game_over():
            outcome = self.board.outcome()

            raise GameOver(f"{outcome.result()} {outcome.termination.name}")
        elif self.board.status() & chess.STATUS_NO_WHITE_KING:
            raise GameOver(f"0-1 CHECKMATE")
        elif self.board.status() & chess.STATUS_NO_BLACK_KING:
            raise GameOver(f"1-0 CHECKMATE")
        elif not self.board.is_valid():
            raise GameOver(f"Некорректное состояние доски.")

    async def move(self, move=None):
        if move is not None:
            try:
                move = chess.Move.from_uci(move)
            except chess.InvalidMoveError:
                raise IllegalMove(move)

            if move not in self.board.legal_moves:
                raise IllegalMove(move)
        else:
            move = await self.engine.play(self.board, chess.engine.Limit(nodes=1))
            move = move.move

        self.board.push(move)
        self.move_ts = time.time()

        self.check_game_over()

    def from_moves(self, moves):
        self.board.reset()

        moves = moves.strip().split(" ")
        if len(moves) > 2048 or len(moves) % 2 != 0:
            raise IllegalMove

        for i, move in zip(range(len(moves)), moves):
            try:
                move = chess.Move.from_uci(move)
            except chess.InvalidMoveError:
                raise IllegalMove(move)
 
            if move not in self.board.legal_moves and not (move == chess.Move.null() and i % 2 == 0):
                raise IllegalMove(move)

            self.board.push(move)

            self.check_game_over()

    def skip(self):
        self.board.push(chess.Move.null())
        self.move_ts = time.time()


class ChessManager:
    def __init__(self, engine_path):
        self.engine_path = engine_path

        self.engine = None
        self.sessions = {}

    async def cleanup(self):
        for id in list(self.sessions.keys()):
            session = self.sessions[id]

            if (
                time.time() - session.move_ts >= 60 * 60 * 12
                or time.time() - session.ts >= 60 * 60 * 24 * 7
            ):
                await self.end(id)

    async def begin(self, id, moves=None):
        if id in self.sessions:
            await self.end(id)

        if not self.engine:
            _, self.engine = await chess.engine.popen_uci(self.engine_path)

        self.sessions[id] = ChessSession(self.engine)

        if moves is not None:
            self.sessions[id].from_moves(moves)

    async def end(self, id):
        session = self.sessions.get(id)
        if not session:
            return False

        del self.sessions[id]

        return True

    async def move(self, id, move=None):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        await session.move(move)

    def undo(self, id):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        session.board.pop()

    def is_check(self, id):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        return session.board.is_check()

    async def skip(self, id):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        session.skip()

    def svg(self, id, size=256):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        arrows = []
        if session.board.move_stack:
            arrows.append((session.board.move_stack[-1].from_square, session.board.move_stack[-1].to_square))

            if len(session.board.move_stack) > 1 and session.board.move_stack[-2] != chess.Move.null():
                arrows.append((session.board.move_stack[-2].from_square, session.board.move_stack[-2].to_square))
 
        move = None

        if session.board.attackers_mask(chess.WHITE, session.board.king(chess.BLACK)) != 0:
            move = session.board.king(chess.BLACK)
          
        if session.board.is_check():
            return chess.svg.board(session.board, size=size, lastmove=move, arrows=arrows, fill={checker: "#cc0000cc" for checker in session.board.checkers()}, check=session.board.king(session.board.turn))

        return chess.svg.board(session.board, size=size, lastmove=move, arrows=arrows)

    def ascii(self, id):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        return str(session.board)

    def has_moves(self, id):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        return bool(session.board.move_stack)

    def moves_count(self, id):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        return len(session.board.move_stack)

    def moves(self, id, offset=None):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        if offset is not None:
            moves = session.board.move_stack[-offset:]
        else:
            moves = session.board.move_stack

        return " ".join(map(str, moves))