(function () {
  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]
  ];

  let board, current, over;
  const cells = document.querySelectorAll('.cell');
  const status = document.getElementById('status');
  const resetBtn = document.getElementById('reset');

  function init() {
    board = Array(9).fill(null);
    current = 'X';
    over = false;
    cells.forEach(c => {
      c.textContent = '';
      c.className = 'cell';
    });
    status.textContent = "Player X's turn";
  }

  function checkWinner() {
    for (const [a, b, c] of WINS) {
      if (board[a] && board[a] === board[b] && board[a] === board[c]) {
        return { winner: board[a], line: [a, b, c] };
      }
    }
    return board.every(Boolean) ? { winner: null, draw: true } : null;
  }

  function handleClick(e) {
    const idx = parseInt(e.target.dataset.index);
    if (over || board[idx]) return;

    board[idx] = current;
    const cell = cells[idx];
    cell.textContent = current;
    cell.classList.add('taken', current.toLowerCase());

    const result = checkWinner();
    if (result) {
      over = true;
      if (result.draw) {
        status.textContent = "It's a draw!";
      } else {
        result.line.forEach(i => cells[i].classList.add('winner'));
        status.textContent = `Player ${result.winner} wins!`;
      }
    } else {
      current = current === 'X' ? 'O' : 'X';
      status.textContent = `Player ${current}'s turn`;
    }
  }

  cells.forEach(c => c.addEventListener('click', handleClick));
  resetBtn.addEventListener('click', init);

  init();
})();