import re
import time

import chess
import chess.svg
import chess.engine


class GameOver(Exception):
    pass


class IllegalMove(Exception):
    pass


def board2svg(board, size=256, shallow=False, orientation=None):
    if orientation is None:
        orientation = board.turn

    arrows = []
    if board.move_stack and board.move_stack[-1] != chess.Move.null():
        arrows.append((board.move_stack[-1].from_square, board.move_stack[-1].to_square))

        if not shallow and len(board.move_stack) > 1 and board.move_stack[-2] != chess.Move.null():
            arrows.append((board.move_stack[-2].from_square, board.move_stack[-2].to_square))
          
    if board.is_check():
        return chess.svg.board(board, orientation=orientation, size=size, arrows=arrows, fill={checker: "#cc0000cc" for checker in board.checkers()}, check=board.king(board.turn))

    return chess.svg.board(board, orientation=orientation, size=size, arrows=arrows)


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

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

    def parse_move(self, move):
        move = move.strip()

        try:
            move = self.board.parse_san(move)
        except (chess.InvalidMoveError, chess.IllegalMoveError, chess.AmbiguousMoveError):
            raise IllegalMove(move)

        return move
        
    def check_game_over(self):
        outcome = self.board.outcome(claim_draw=True)

        if outcome is not None:
            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:
            move = self.parse_move(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, strict=True):
        self.board.reset()

        moves = moves.strip()
        if moves.startswith("1."):
            text = moves
            moves = []

            while text and len(moves) < 600:
                match = re.match(r"^(?:\d+\. ?([^.\s]+) ([^.\s]+))", text)
                if not match:
                    raise IllegalMove

                moves.extend((match.group(1), match.group(2)))           

                text = text[match.end() - match.start():].strip()
        else:
            moves = moves.split(" ")
            if len(moves) > 600 or (strict and len(moves) % 2 != 0):
                raise IllegalMove

        for i, move in zip(range(len(moves)), moves):
            move = self.parse_move(move)
 
            if strict and 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, strict=True):
        if id in self.sessions:
            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, strict=strict)

    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, shallow=False):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        return board2svg(session.board, size=size, shallow=shallow)

    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))

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

        return session.board.turn

    def animate(self, id, count=None, size=256, shallow=False):
        session = self.sessions.get(id)
        if not session:
            raise KeyError(id)

        board = chess.Board()
        frames = []

        frames.append(board2svg(board, size=size, shallow=shallow, orientation=chess.WHITE))

        for move in session.board.move_stack:
            board.push(move)

            frames.append(board2svg(board, size=size, shallow=shallow, orientation=chess.WHITE))

            if count is not None and len(frames) >= count:
                break

        return frames