text: import React from 'react';
  import ReactDOM from 'react-dom';
  import { BrowserRouter as Router, Route, Link } from "react-router-dom";
  
  import './index.css';
  
  
  function Square (props){
        return (
          <button className="square" onClick={props.onClick}>
            {props.value}
          </button>
        );
    }
    
    class Board extends React.Component {
  
      renderSquare(i, row, column) {
        return <Square value={this.props.squares[i]}
        onClick={() => this.props.onClick(i,row, column)} />;
      }
    
      render() {
        
        return (
          <div>
            <div className="board-row">
              {this.renderSquare(0,1,1)}
              {this.renderSquare(1,1,2)}
              {this.renderSquare(2,1,3)}
            </div>
            <div className="board-row">
              {this.renderSquare(3,2,1)}
              {this.renderSquare(4,2,2)}
              {this.renderSquare(5,2,3)}
            </div>
            <div className="board-row">
              {this.renderSquare(6,3,1)}
              {this.renderSquare(7,3,2)}
              {this.renderSquare(8,3,3)}
            </div>
          </div>
        );
      }
    }
    
    class Game extends React.Component {
      constructor(props) {
        super(props);
        this.state = {
          history: [{
            squares: Array(9).fill(null),
          }],
          location: [],
          stepNumber: 0,
          xIsNext: true,
        }
      }
      handleClick(i, row, column) {
        const history = this.state.history.slice(0, this.state.stepNumber + 1);
        let location = this.state.location;
        location.push({row: row, column: column});
        const current = history[history.length - 1];
        const squares = current.squares.slice();
        if (calculateWinner(squares) || squares[i]) {
          return;
        }
        squares[i] = this.state.xIsNext ? 'X' : 'O';
        this.setState({
          history: history.concat([{
            squares: squares,
          }]),
          location: location,
          stepNumber: history.length,
          xIsNext: !this.state.xIsNext,
          row: row,
          column: column,
        });
      }
      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) => {
          let locationIndex = move ? move - 1 : move;
          console.log(move);
          const row = this.state.location.length ? this.state.location[locationIndex].row : null;
          const column = this.state.location.length ? this.state.location[locationIndex].column : null;
          const desc = move ?
            'Go to move #' + move + '(' + row + ',' + column + ')':
            'Go to game start';
  
          return (
            <li key={move} className={"current"}>
              <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,row, column) => this.handleClick(i, row, column)} />
            </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;
    }
  
  
    