<div id="errors" style="
  background: #c00;
  color: #fff;
  display: none;
  margin: -20px -20px 20px;
  padding: 20px;
  white-space: pre-wrap;
"></div>
<div id="root"></div>
<script>
window.addEventListener('mousedown', function(e) {
  document.body.classList.add('mouse-navigation');
  document.body.classList.remove('kbd-navigation');
});
window.addEventListener('keydown', function(e) {
  if (e.keyCode === 9) {
    document.body.classList.add('kbd-navigation');
    document.body.classList.remove('mouse-navigation');
  }
});
window.addEventListener('click', function(e) {
  if (e.target.tagName === 'A' && e.target.getAttribute('href') === '#') {
    e.preventDefault();
  }
});
window.onerror = function(message, source, line, col, error) {
  var text = error ? error.stack || error : message + ' (at ' + source + ':' + line + ':' + col + ')';
  errors.textContent += text + '\n';
  errors.style.display = '';
};
console.error = (function(old) {
  return function error() {
    errors.textContent += Array.prototype.slice.call(arguments).join(' ') + '\n';
    errors.style.display = '';
    old.apply(this, arguments);
  }
})(console.error);
</script>

* {
  margin: 0;
  padding: 0;
}

body {
  font: 14px "Century Gothic", Futura, sans-serif;
  margin: 20px;
}

ul,
ol {
  list-style: none;
}

li {
  margin-top: 5px;
}

li > button {
  padding: 5px 15px;
  width: 200px;
}

.board-row:after {
  clear: both;
  content: "";
  display: table;
}

.status {
  margin-bottom: 10px;
  font-size: 1.5rem;
  font-weight: bold;
}

.square {
  background: #fff;
  border: 1px solid #999;
  float: left;
  font-size: 24px;
  font-weight: bold;
  line-height: 34px;
  height: 34px;
  margin-right: -1px;
  margin-top: -1px;
  padding: 0;
  text-align: center;
  width: 34px;
}

.square:focus {
  outline: none;
}

.kbd-navigation .square:focus {
  background: #ddd;
}

.game {
  display: flex;
  flex-direction: column;
  align-items: center;
}

function Square (props){
  return (
    <button
    className="square"
    onClick={props.onClick}>
      {props.value}
    </button>
  );
}

class Board extends React.Component {
  renderSquare(i) {
    return (
      <Square
              value={this.props.squares[i]}
              onClick={() => this.props.onClick(i)} />
    );
  }

  render() {
    return (
      <div>
        <div className="board-row">
          {this.renderSquare(0)}
          {this.renderSquare(1)}
          {this.renderSquare(2)}
        </div>
        <div className="board-row">
          {this.renderSquare(3)}
          {this.renderSquare(4)}
          {this.renderSquare(5)}
        </div>
        <div className="board-row">
          {this.renderSquare(6)}
          {this.renderSquare(7)}
          {this.renderSquare(8)}
        </div>
      </div>
    );
  }
}

class Game extends React.Component {
  constructor(props){
    super(props);
    this.state = {
      history: [{
        squares: Array(9).fill(null),
      }],
      turn: "X"
    }
  }
  
  handleClick (i){
    const history = this.state.history;
    const current = history[history.length-1];
    const squares = current.squares.slice();
    if(calculateWinner(squares) || squares[i])
      return;
    const curr = this.state.turn;
    squares[i] = curr;
    const next = curr === "X" ? "O" : "X";
    this.setState({
      history: history.concat([{
        squares: squares
      }]),
      turn: next
    });
  }

  renderList (){
    this.state.history.map(el => <li>el</li>)

  }

  jumpTo (move){
    const history = this.state.history.slice(0, move+1);
    const next = move%2 === 0 ? "X" : "O";
    this.setState({
      history: history,
      turn: next
    });    
  }

  render() {
    const history = this.state.history;
    const current = history[history.length-1];
    const winner = calculateWinner(current.squares);

    const moves = history.map((step, move) => {
      const desc = move ? "Go to move #"+move :
                          "Go to game start";
      return (
        <li key={move}>
          <button onClick={() => this.jumpTo(move)}>
            {desc}
          </button>
        </li>
      );
    }).splice(0, history.length-1);

    let status;
    if(winner){
      status = "Winner is " +winner;
    } else {
      status = `Next player: ${this.state.turn}`;
    }
    return (
      <div className="game">
        <div className="status">{status}</div>
        <div className="game-board">
          <Board            
            squares={current.squares}
            onClick={(i) => this.handleClick(i)} />
        </div>
        <div className="game-info">
          <ol>{moves}</ol>
        </div>
      </div>
    );
  }
}

// ========================================

const root = ReactDOM.createRoot(document.getElementById("root"));
root.render(<Game />);

function calculateWinner(squares) {
  const 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],
  ];
  for (let i = 0; i < lines.length; i++) {
    const [a, b, c] = lines[i];
    if (squares[a] && squares[a] === squares[b] && squares[a] === squares[c]) {
      return squares[a];
    }
  }
  return null;
}