import {
  createGameCommandRegistry,
  Part,
  MutableSignal,
  createRegion,
  createPart,
  isCellOccupied as isCellOccupiedUtil,
  getPartAtPosition,
} from 'boardgame-core';

const BOARD_SIZE = 6;
const MAX_PIECES_PER_PLAYER = 8;
const WIN_LENGTH = 3;

export type PlayerType = 'white' | 'black';
export type PieceType = 'kitten' | 'cat';
export type WinnerType = PlayerType | 'draw' | null;

export type BoopPart = Part<{ player: PlayerType; pieceType: PieceType }>;

type PieceSupply = { supply: number; placed: number };

type Player = {
    id: PlayerType;
    kitten: PieceSupply;
    cat: PieceSupply;
};

type PlayerData = Record<PlayerType, Player>;

export function createInitialState() {
    return {
        board: createRegion('board', [
            { name: 'x', min: 0, max: BOARD_SIZE - 1 },
            { name: 'y', min: 0, max: BOARD_SIZE - 1 },
        ]),
        pieces: {} as Record<string, BoopPart>,
        currentPlayer: 'white' as PlayerType,
        winner: null as WinnerType,
        players: {
            white: createPlayer('white'),
            black: createPlayer('black'),
        },
    };
}

function createPlayer(id: PlayerType): Player {
    return {
        id,
        kitten: { supply: MAX_PIECES_PER_PLAYER, placed: 0 },
        cat: { supply: 0, placed: 0 },
    };
}

export type BoopState = ReturnType<typeof createInitialState>;
const registration = createGameCommandRegistry<BoopState>();
export const registry = registration.registry;

export function getPlayer(host: MutableSignal<BoopState>, player: PlayerType): Player {
    return host.value.players[player];
}

export function decrementSupply(player: Player, pieceType: PieceType) {
    player[pieceType].supply--;
    player[pieceType].placed++;
}

export function incrementSupply(player: Player, pieceType: PieceType, count?: number) {
    player[pieceType].supply += count ?? 1;
}

registration.add('setup', async function() {
    const {context} = this;
    while (true) {
        const currentPlayer = context.value.currentPlayer;
        const turnOutput = await this.run<{winner: WinnerType}>(`turn ${currentPlayer}`);
        if (!turnOutput.success) throw new Error(turnOutput.error);

        context.produce(state => {
            state.winner = turnOutput.result.winner;
            if (!state.winner) {
                state.currentPlayer = state.currentPlayer === 'white' ? 'black' : 'white';
            }
        });
        if (context.value.winner) break;
    }

    return context.value;
});

registration.add('turn <player>', async function(cmd) {
    const [turnPlayer] = cmd.params as [PlayerType];

    const playCmd = await this.prompt(
        'play <player> <row:number> <col:number> [type:string]',
        (command) => {
            const [player, row, col, type] = command.params as [PlayerType, number, number, PieceType?];
            const pieceType = type === 'cat' ? 'cat' : 'kitten';

            if (player !== turnPlayer) {
                return `Invalid player: ${player}. Expected ${turnPlayer}.`;
            }
            if (!isValidMove(row, col)) {
                return `Invalid position: (${row}, ${col}). Must be between 0 and ${BOARD_SIZE - 1}.`;
            }
            if (isCellOccupied(this.context, row, col)) {
                return `Cell (${row}, ${col}) is already occupied.`;
            }

            const playerData = getPlayer(this.context, player);
            const supply = playerData[pieceType].supply;
            if (supply <= 0) {
                return `No ${pieceType}s left in ${player}'s supply.`;
            }
            return null;
        },
        this.context.value.currentPlayer
    );
    const [player, row, col, type] = playCmd.params as [PlayerType, number, number, PieceType?];
    const pieceType = type === 'cat' ? 'cat' : 'kitten';

    placePiece(this.context, row, col, turnPlayer, pieceType);
    applyBoops(this.context, row, col, pieceType);

    const graduatedLines = checkGraduation(this.context, turnPlayer);
    if (graduatedLines.length > 0) {
        processGraduation(this.context, turnPlayer, graduatedLines);
    }

    if (countPiecesOnBoard(this.context, turnPlayer) >= MAX_PIECES_PER_PLAYER) {
        const pieces = this.context.value.pieces;
        const availableKittens = Object.values(pieces).filter(
            p => p.player === turnPlayer && p.pieceType === 'kitten'
        );

        if (availableKittens.length > 0) {
            const graduateCmd = await this.prompt(
                'graduate <row:number> <col:number>',
                (command) => {
                    const [row, col] = command.params as [number, number];
                    const posKey = `${row},${col}`;
                    const part = availableKittens.find(p => `${p.position[0]},${p.position[1]}` === posKey);
                    if (!part) return `No kitten at (${row}, ${col}).`;
                    return null;
                },
                this.context.value.currentPlayer
            );
            const [row, col] = graduateCmd.params as [number, number];
            const part = availableKittens.find(p => p.position[0] === row && p.position[1] === col)!;
            removePieceFromBoard(this.context, part);
            const playerData = getPlayer(this.context, turnPlayer);
            incrementSupply(playerData, 'cat', 1);
        }
    }

    const winner = checkWinner(this.context);
    if (winner) return { winner };

    return { winner: null };
});

function isValidMove(row: number, col: number): boolean {
    return !isNaN(row) && !isNaN(col) && row >= 0 && row < BOARD_SIZE && col >= 0 && col < BOARD_SIZE;
}

export function getBoardRegion(host: MutableSignal<BoopState>) {
    return host.value.board;
}

export function isCellOccupied(host: MutableSignal<BoopState>, row: number, col: number): boolean {
    return isCellOccupiedUtil(host.value.pieces, 'board', [row, col]);
}

export function getPartAt(host: MutableSignal<BoopState>, row: number, col: number): BoopPart | null {
    return getPartAtPosition(host.value.pieces, 'board', [row, col]) || null;
}

export function placePiece(host: MutableSignal<BoopState>, row: number, col: number, player: PlayerType, pieceType: PieceType) {
    const board = getBoardRegion(host);
    const playerData = getPlayer(host, player);
    const count = playerData[pieceType].placed + 1;

    const piece = createPart<{ player: PlayerType; pieceType: PieceType }>(
        { regionId: 'board', position: [row, col], player, pieceType },
        `${player}-${pieceType}-${count}`
    );
    host.produce(s => {
        s.pieces[piece.id] = piece;
        board.childIds.push(piece.id);
        board.partMap[`${row},${col}`] = piece.id;
    });
    decrementSupply(playerData, pieceType);
}

export function applyBoops(host: MutableSignal<BoopState>, placedRow: number, placedCol: number, placedType: PieceType) {
    const pieces = host.value.pieces;
    const piecesArray = Object.values(pieces);

    const piecesToBoop: { part: BoopPart; dr: number; dc: number }[] = [];

    for (const part of piecesArray) {
        const [r, c] = part.position;
        if (r === placedRow && c === placedCol) continue;

        const dr = Math.sign(r - placedRow);
        const dc = Math.sign(c - placedCol);

        if (Math.abs(r - placedRow) <= 1 && Math.abs(c - placedCol) <= 1) {
            const booperIsKitten = placedType === 'kitten';
            const targetIsCat = part.pieceType === 'cat';

            if (booperIsKitten && targetIsCat) continue;

            piecesToBoop.push({ part, dr, dc });
        }
    }

    host.produce(state => {
        const board = state.board;
        const currentPieces = state.pieces;

        for (const { part, dr, dc } of piecesToBoop) {
            const [r, c] = part.position;
            const newRow = r + dr;
            const newCol = c + dc;

            if (newRow < 0 || newRow >= BOARD_SIZE || newCol < 0 || newCol >= BOARD_SIZE) {
                const pt = part.pieceType;
                const pl = part.player;
                const playerData = state.players[pl];
                // Remove piece from board
                board.childIds = board.childIds.filter(id => id !== part.id);
                delete board.partMap[part.position.join(',')];
                delete currentPieces[part.id];
                playerData[pt].placed--;
                playerData[pt].supply++;
                continue;
            }

            // Check if target cell is occupied
            const targetPosKey = `${newRow},${newCol}`;
            if (board.partMap[targetPosKey]) continue;

            // Move piece to new position
            delete board.partMap[part.position.join(',')];
            part.position = [newRow, newCol];
            board.partMap[targetPosKey] = part.id;
        }
    });
}

export function removePieceFromBoard(host: MutableSignal<BoopState>, part: BoopPart) {
    host.produce(state => {
        const board = state.board;
        const playerData = state.players[part.player];
        board.childIds = board.childIds.filter(id => id !== part.id);
        delete board.partMap[part.position.join(',')];
        delete state.pieces[part.id];
        playerData[part.pieceType].placed--;
    });
}

const DIRECTIONS: [number, number][] = [
    [0, 1],
    [1, 0],
    [1, 1],
    [1, -1],
];

export function* linesThrough(r: number, c: number): Generator<number[][]> {
    for (const [dr, dc] of DIRECTIONS) {
        const minStart = -(WIN_LENGTH - 1);
        for (let offset = minStart; offset <= 0; offset++) {
            const startR = r + offset * dr;
            const startC = c + offset * dc;
            const endR = startR + (WIN_LENGTH - 1) * dr;
            const endC = startC + (WIN_LENGTH - 1) * dc;

            if (startR < 0 || startR >= BOARD_SIZE || startC < 0 || startC >= BOARD_SIZE) continue;
            if (endR < 0 || endR >= BOARD_SIZE || endC < 0 || endC >= BOARD_SIZE) continue;

            const line: number[][] = [];
            for (let i = 0; i < WIN_LENGTH; i++) {
                line.push([startR + i * dr, startC + i * dc]);
            }
            yield line;
        }
    }
}

export function* allLines(): Generator<number[][]> {
    const seen = new Set<string>();
    for (let r = 0; r < BOARD_SIZE; r++) {
        for (let c = 0; c < BOARD_SIZE; c++) {
            for (const line of linesThrough(r, c)) {
                const key = line.map(p => p.join(',')).join(';');
                if (!seen.has(key)) {
                    seen.add(key);
                    yield line;
                }
            }
        }
    }
}

export function hasWinningLine(positions: number[][]): boolean {
    const posSet = new Set(positions.map(p => `${p[0]},${p[1]}`));
    for (const line of allLines()) {
        if (line.every(([lr, lc]) => posSet.has(`${lr},${lc}`))) return true;
    }
    return false;
}

export function checkGraduation(host: MutableSignal<BoopState>, player: PlayerType): number[][][] {
    const pieces = host.value.pieces;
    const piecesArray = Object.values(pieces);
    const posSet = new Set<string>();

    for (const part of piecesArray) {
        if (part.player === player && part.pieceType === 'kitten') {
            posSet.add(`${part.position[0]},${part.position[1]}`);
        }
    }

    const winningLines: number[][][] = [];
    for (const line of allLines()) {
        if (line.every(([lr, lc]) => posSet.has(`${lr},${lc}`))) {
            winningLines.push(line);
        }
    }
    return winningLines;
}

export function processGraduation(host: MutableSignal<BoopState>, player: PlayerType, lines: number[][][]) {
    const allPositions = new Set<string>();
    for (const line of lines) {
        for (const [r, c] of line) {
            allPositions.add(`${r},${c}`);
        }
    }

    const board = getBoardRegion(host);
    const pieces = host.value.pieces;
    const partsToRemove = Object.values(pieces).filter(
        p => p.player === player && p.pieceType === 'kitten' && allPositions.has(`${p.position[0]},${p.position[1]}`)
    );

    for (const part of partsToRemove) {
        removePieceFromBoard(host, part);
    }

    const count = partsToRemove.length;
    const playerData = getPlayer(host, player);
    incrementSupply(playerData, 'cat', count);
}

export function countPiecesOnBoard(host: MutableSignal<BoopState>, player: PlayerType): number {
    const pieces = host.value.pieces;
    return Object.values(pieces).filter(p => p.player === player).length;
}

export function checkWinner(host: MutableSignal<BoopState>): WinnerType {
    const pieces = host.value.pieces;
    const piecesArray = Object.values(pieces);

    for (const player of ['white', 'black'] as PlayerType[]) {
        const positions = piecesArray
            .filter(p => p.player === player && p.pieceType === 'cat')
            .map(p => p.position);
        if (hasWinningLine(positions)) return player;
    }

    return null;
}

// 命令构建器
export const commands = {
  play: (player: PlayerType, row: number, col: number, type?: PieceType) => 
    `play ${player} ${row} ${col}${type ? ` ${type}` : ''}`,
  turn: (player: PlayerType) => `turn ${player}`,
  graduate: (row: number, col: number) => `graduate ${row} ${col}`,
} as const;

// 导出游戏模块
export const gameModule = {
  createInitialState,
  registry,
  commands,
};