'use strict';

const path = require('path');
const http = require('http');
const crypto = require('crypto');
const express = require('express');
const WebSocket = require('ws');
const db = require('./db');

const PORT = process.env.PORT || 8080;
const BASE_PATH = process.env.BASE_PATH || '';

const WIN_LINES = [
  [0, 1, 2], [3, 4, 5], [6, 7, 8],
  [0, 3, 6], [1, 4, 7], [2, 5, 8],
  [0, 4, 8], [2, 4, 6],
];

function checkWinner(board) {
  for (const line of WIN_LINES) {
    const [a, b, c] = line;
    if (board[a] && board[a] === board[b] && board[a] === board[c]) {
      return { winner: board[a], line };
    }
  }
  if (board.every((v) => v !== null)) return { winner: 'draw' };
  return null;
}

const app = express();
const server = http.createServer(app);
const wss = new WebSocket.Server({ server, path: '/ws' });

const games = new Map();

app.use(express.static(path.join(__dirname, '../public')));

app.post('/api/games', (req, res) => {
  const id = crypto.randomUUID();
  const token = crypto.randomBytes(8).toString('hex');
  db.createGame({ id, token });
  const link = `${req.get('origin') || req.protocol + '://' + req.get('host')}${BASE_PATH}/?token=${token}`;
  res.status(201).json({ id, token, link });
});

app.get('/api/health', (req, res) => {
  res.json({ ok: true });
});

app.use((req, res, next) => {
  if (req.method === 'GET' && !req.path.startsWith('/api/')) {
    res.sendFile(path.join(__dirname, '../public', 'index.html'));
  } else {
    next();
  }
});

function send(ws, obj) {
  if (ws.readyState === WebSocket.OPEN) {
    ws.send(JSON.stringify(obj));
  }
}

function broadcast(game, obj) {
  for (const seat of ['X', 'O']) {
    const p = game.players[seat];
    if (p) send(p, obj);
  }
}

wss.on('connection', (ws) => {
  ws.on('message', (raw) => {
    let msg;
    try {
      msg = JSON.parse(raw.toString());
    } catch (e) {
      return;
    }

    switch (msg.type) {
      case 'host':
        handleHost(ws, msg);
        break;
      case 'join':
        handleJoin(ws, msg);
        break;
      case 'move':
        handleMove(ws, msg);
        break;
      case 'new-round':
        handleNewRound(ws, msg);
        break;
      case 'leave':
        handleLeave(ws);
        break;
    }
  });

  ws.on('close', () => {
    handleDisconnect(ws);
  });
});

function handleHost(ws, msg) {
  const row = db.getGameById(msg.id);
  if (!row) {
    send(ws, { type: 'error', message: 'Game not found' });
    return;
  }

  let game = games.get(row.id);
  if (!game) {
    const board = row.board === 'null' ? Array(9).fill(null) : JSON.parse(row.board);
    game = {
      id: row.id,
      token: row.token,
      board,
      turn: row.turn,
      status: row.status,
      players: { X: null, O: null },
    };
    games.set(game.id, game);
  }

  game.players.X = ws;
  ws._gameId = game.id;
  ws._seat = 'X';

  if (game.status === 'waiting') {
    send(ws, { type: 'joined', mark: 'X', board: game.board, turn: game.turn });
  } else if (game.status === 'playing' && game.players.O) {
    send(ws, { type: 'start', mark: 'X', first: 'X', board: game.board, turn: game.turn });
  }
}

function handleJoin(ws, msg) {
  const row = db.getGameByToken(msg.token);
  if (!row) {
    send(ws, { type: 'error', message: 'Invalid or expired link' });
    return;
  }

  let game = games.get(row.id);

  if (!game) {
    const board = row.board === 'null' ? Array(9).fill(null) : JSON.parse(row.board);
    game = {
      id: row.id,
      token: row.token,
      board,
      turn: row.turn,
      status: row.status,
      players: { X: null, O: ws },
    };
    games.set(game.id, game);
  }

  if (game.status === 'ended') {
    send(ws, { type: 'error', message: 'Game already ended' });
    return;
  }

  if (game.players.O) {
    send(ws, { type: 'error', message: 'Game already full' });
    return;
  }

  game.players.O = ws;
  ws._gameId = game.id;
  ws._seat = 'O';

  if (game.players.X) {
    game.status = 'playing';
    db.updateGame(game.id, { status: 'playing', board: JSON.stringify(game.board), turn: game.turn });
    send(game.players.X, { type: 'opponent-joined', you: 'X' });
    send(ws, { type: 'start', mark: 'O', first: 'X', board: game.board, turn: game.turn });
  } else {
    send(ws, { type: 'joined', mark: 'O', board: game.board, turn: game.turn });
  }
}

function handleMove(ws, msg) {
  const game = games.get(ws._gameId);
  if (!game) {
    send(ws, { type: 'error', message: 'Game not found' });
    return;
  }

  if (game.status !== 'playing') {
    send(ws, { type: 'error', message: 'Game is not in progress' });
    return;
  }

  const seat = ws._seat;
  if (game.turn !== seat) {
    send(ws, { type: 'error', message: 'Not your turn' });
    return;
  }

  const cell = msg.index;
  if (!Number.isInteger(cell) || cell < 0 || cell > 8) {
    send(ws, { type: 'error', message: 'Invalid cell' });
    return;
  }

  if (game.board[cell] !== null) {
    send(ws, { type: 'error', message: 'Cell already occupied' });
    return;
  }

  game.board[cell] = seat;
  game.turn = seat === 'X' ? 'O' : 'X';
  db.updateGame(game.id, { status: game.status, board: JSON.stringify(game.board), turn: game.turn });

  const result = checkWinner(game.board);

  broadcast(game, { type: 'move', index: cell, mark: seat });

  if (result) {
    game.status = 'ended';
    db.updateGame(game.id, { status: 'ended', board: JSON.stringify(game.board), turn: game.turn });
    broadcast(game, { type: 'end', winner: result.winner, line: result.line || null });
  }
}

function handleNewRound(ws, msg) {
  const game = games.get(ws._gameId);
  if (!game) {
    send(ws, { type: 'error', message: 'Game not found' });
    return;
  }

  if (game.status !== 'ended') {
    send(ws, { type: 'error', message: 'Game has not ended' });
    return;
  }

  game.board = Array(9).fill(null);
  game.turn = 'X';
  game.status = 'playing';
  db.updateGame(game.id, { status: 'playing', board: JSON.stringify(game.board), turn: game.turn });

  broadcast(game, { type: 'new-round', first: 'X', board: game.board, turn: game.turn });
}

function handleLeave(ws) {
  handleDisconnect(ws);
}

function handleDisconnect(ws) {
  const gameId = ws._gameId;
  if (!gameId) return;

  const game = games.get(gameId);
  if (!game) return;

  const seat = ws._seat;
  if (game.players[seat] === ws) {
    game.players[seat] = null;
  }

  if (game.status === 'playing') {
    game.status = 'ended';
    db.updateGame(game.id, { status: 'ended', board: JSON.stringify(game.board), turn: game.turn });

    const otherSeat = seat === 'X' ? 'O' : 'X';
    const other = game.players[otherSeat];
    if (other) {
      send(other, { type: 'opponent-left' });
    }
  } else if (game.status === 'waiting' && seat === 'X') {
    game.status = 'ended';
    db.updateGame(game.id, { status: 'ended', board: JSON.stringify(game.board), turn: game.turn });
  }

  if (!game.players.X && !game.players.O) {
    games.delete(game.id);
  }
}

db.init().then(() => {
  server.listen(PORT, '0.0.0.0', () => {
    console.log(`Server running on port ${PORT}`);
  });
}).catch((err) => {
  console.error('Failed to initialize database:', err);
  process.exit(1);
});