const boardDiv = document.getElementById('board');
const statusDiv = document.getElementById('status');
const restartBtn = document.getElementById('restart-btn');
let board, gameOver;

function initGame() {
  board = Array(9).fill('');
  gameOver = false;
  statusDiv.textContent = "Tu turno (X)";
  renderBoard();
}

function renderBoard() {
  boardDiv.innerHTML = '';
  board.forEach((cell, idx) => {
    const cellDiv = document.createElement('div');
    cellDiv.className = 'cell';
    cellDiv.textContent = cell;
    cellDiv.onclick = () => handlePlayerMove(idx);
    boardDiv.appendChild(cellDiv);
  });
}

function handlePlayerMove(idx) {
  if (gameOver || board[idx] !== '') return;
  board[idx] = 'X';
  renderBoard();
  if (checkWinner('X')) {
    statusDiv.textContent = `¡Tú ganas! 🎉`;
    gameOver = true;
    return;
  }
  if (isDraw()) {
    statusDiv.textContent = "¡Empate!";
    gameOver = true;
    return;
  }
  statusDiv.textContent = "Turno de la máquina (O)";
  setTimeout(machineMove, 400);
}

function machineMove() {
  if (gameOver) return;
  let bestScore = -Infinity;
  let move = null;
  for (let i = 0; i < 9; i++) {
    if (board[i] === '') {
      board[i] = 'O';
      let score = minimax(board, 0, false);
      board[i] = '';
      if (score > bestScore) {
        bestScore = score;
        move = i;
      }
    }
  }
  if (move !== null) board[move] = 'O';
  renderBoard();
  if (checkWinner('O')) {
    statusDiv.textContent = `¡La máquina gana! 🤖`;
    gameOver = true;
    return;
  }
  if (isDraw()) {
    statusDiv.textContent = "¡Empate!";
    gameOver = true;
    return;
  }
  statusDiv.textContent = "Tu turno (X)";
}

// Algoritmo Minimax
function minimax(newBoard, depth, isMaximizing) {
  if (checkWinnerOnBoard(newBoard, 'O')) return 10 - depth;
  if (checkWinnerOnBoard(newBoard, 'X')) return depth - 10;
  if (newBoard.every(cell => cell !== '')) return 0;

  if (isMaximizing) {
    let bestScore = -Infinity;
    for (let i = 0; i < 9; i++) {
      if (newBoard[i] === '') {
        newBoard[i] = 'O';
        let score = minimax(newBoard, depth + 1, false);
        newBoard[i] = '';
        bestScore = Math.max(score, bestScore);
      }
    }
    return bestScore;
  } else {
    let bestScore = Infinity;
    for (let i = 0; i < 9; i++) {
      if (newBoard[i] === '') {
        newBoard[i] = 'X';
        let score = minimax(newBoard, depth + 1, true);
        newBoard[i] = '';
        bestScore = Math.min(score, bestScore);
      }
    }
    return bestScore;
  }
}

function checkWinner(player) {
  return checkWinnerOnBoard(board, player);
}

function checkWinnerOnBoard(b, player) {
  const wins = [
    [0,1,2],[3,4,5],[6,7,8],
    [0,3,6],[1,4,7],[2,5,8],
    [0,4,8],[2,4,6]
  ];
  return wins.some(combo => combo.every(i => b[i] === player));
}

function isDraw() {
  return board.every(cell => cell !== '') && !checkWinner('X') && !checkWinner('O');
}

restartBtn.onclick = initGame;

initGame();