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

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

render() {
  return (
    <div className="board">
    {
      [1,2,3].map( (x) => {
       return <div key={x} className="board-row">
          {
            [1*(x+1),2*(x+2),3*(x+3)].map( (y) => {
                return this.renderSquare(y);
            })
          }
          </div>
      })
    }
    </div>
  )
}
}


class Game extends React.Component {
  constructor(props) {
      super (props);
      this.state = {
          history: [{
              squares: Array(9).fill(null),
          }],
          stepNumber: 0,
          xIsNext: true
      };
  }

  //----------------------History Component---------------------
  handleClick(i)  {
    console.log("does this do anything?")
      const history = this.state.history.slice(0, this.state.stepNumber +1);
      const current = history[history.length - 1];
      const squares = current.squares.slice();
      // Calls a copy of squares array to modify
      if(calculateWinner(squares) || squares[i]) {
          return;
      }
      // Returns early by ignoring click if there is a winner or            square is filled.
      squares[i] = this.state.xIsNext ? 'X' : 'O';
      this.setState({
          history: history.concat([{
              squares: squares
            }]),
          stepNumber: history.length,
          xIsNext: !this.state.xIsNext,
      });
  }

  jumpTo(step) {
      this.setState({
          stepNumber:step,
          xIsNext: (step % 2) === 0,
      });
  }

  render() {
      const history = this.state.history;
      const current = history[this.state.stepNumber];
      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>
          );
      });

      let status;
      if (winner) {
        status = 'Winner: ' + winner;
      } else {
        status = 'Next player: ' + (this.state.xIsNext ? 'X' :              'O');
      }

    return (
      <div className="game">
        <div className="game-board">
          <Board
          squares={current.squares}
          onClick={(i) => this.handleClick(i)}/>
        </div>
        <div className="game-info">
          <div>{status}</div>
          <ol>{moves}</ol>
        </div>
      </div>
    );
  }
}

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

ReactDOM.render(
  <Game />,
  document.getElementById('root')
);

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;
}