import 'package:flutter/material.dart';
    import 'dart:math';

    void main() {
      runApp(TTTApp());
    }

    class TTTApp extends StatelessWidget {
      @override
      Widget build(BuildContext context) {
        return new MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'Tic Tac Toe',
          theme: new ThemeData(
            primarySwatch: Colors.blue,
          ),
          home: new MyHomePage(title: 'Tic Tac Toe'),
        );
      }
    }


    class MyHomePage extends StatefulWidget {
      MyHomePage({Key key, this.title}) : super(key: key);

      final String title;

      @override
      _MyHomePageState createState() => _MyHomePageState();
    }

    class _MyHomePageState extends State<MyHomePage> {

      String _mText = "";

      // Initial Text for infoLabel
      String _text = "X's Turn";

      // constant characters for each player

      static const String HUMAN_PLAYER = "X";
      static const String COMPUTER_PLAYER = "O";

      // constant for board size
      static const BOARD_SIZE = 9;

      // Game variables
      var gameOver = false;
      var win = 0;
      var turn = 0;
      var _mBoard = ["1", "2", "3", "4", "5", "6", "7", "8", "9"];
      var rnd = new Random(BOARD_SIZE);

      // Print board to console

      void displayBoard() {
        print(_mBoard[0] + " | " + _mBoard[1] + " | " + _mBoard[2]);
        print("-----------");
        print(_mBoard[3] + " | " + _mBoard[4] + " | " + _mBoard[5]);
        print("-----------");
        print(_mBoard[6] + " | " + _mBoard[7] + " | " + _mBoard[8]);
      }

      // Check board for winner
      int checkWinner() {
        // Check horizontal wins
        for (int i = 0; i <= 6; i += 3) {
          if (_mBoard[i] == (HUMAN_PLAYER) &&
              _mBoard[i + 1] == (HUMAN_PLAYER) &&
              _mBoard[i + 2] == (HUMAN_PLAYER)) return 2;

          if (_mBoard[i] == (COMPUTER_PLAYER) &&
              _mBoard[i + 1] == (COMPUTER_PLAYER) &&
              _mBoard[i + 2] == (COMPUTER_PLAYER)) return 3;
        }

        // Check vertical wins
        for (int i = 0; i <= 2; i++) {
          if (_mBoard[i] == (HUMAN_PLAYER) &&
              _mBoard[i + 3] == (HUMAN_PLAYER) &&
              _mBoard[i + 6] == (HUMAN_PLAYER)) return 2;

          if (_mBoard[i] == (COMPUTER_PLAYER) &&
              _mBoard[i + 3] == (COMPUTER_PLAYER) &&
              _mBoard[i + 6] == (COMPUTER_PLAYER)) return 3;
        }

        // Check for diagonal wins
        if ((_mBoard[0] == (HUMAN_PLAYER) &&
            _mBoard[4] == (HUMAN_PLAYER) &&
            _mBoard[8] == (HUMAN_PLAYER)) ||
            (_mBoard[2] == (HUMAN_PLAYER) &&
                _mBoard[4] == (HUMAN_PLAYER) &&
                _mBoard[6] == (HUMAN_PLAYER))) return 2;

        if ((_mBoard[0] == (COMPUTER_PLAYER) &&
            _mBoard[4] == (COMPUTER_PLAYER) &&
            _mBoard[8] == (COMPUTER_PLAYER)) ||
            (_mBoard[2] == (COMPUTER_PLAYER) &&
                _mBoard[4] == (COMPUTER_PLAYER) &&
                _mBoard[6] == (COMPUTER_PLAYER))) return 3;

        for (int i = 0; i < BOARD_SIZE; i++) {
          // If we find a number, then no one has won yet
          if (!(_mBoard[i] == (HUMAN_PLAYER)) && !(_mBoard[i] == (COMPUTER_PLAYER)))
            return 0;
        }

        // If we make it through the previous loop, all places are taken, so it's a tie*/
        return 1;
      }

      void computerTurn() {
        var move;
        displayMessage(COMPUTER_PLAYER + " MOVED, X's TURN");

        // First see if there's a move O can make to win
        for (int i = 0; i < BOARD_SIZE; i++) {
          if (!(_mBoard[i] == (HUMAN_PLAYER)) &&
              !(_mBoard[i] == (COMPUTER_PLAYER))) {
            String curr = _mBoard[i];
            _mBoard[i] = COMPUTER_PLAYER;
            _mText = "O";
            if (checkWinner() == 3) {
              return;
            } else
              _mBoard[i] = curr;
          }
        }

        // See if there's a move O can make to block X from winning
        for (int i = 0; i < BOARD_SIZE; i++) {
          if (!(_mBoard[i] == (HUMAN_PLAYER)) &&
              !(_mBoard[i] == (COMPUTER_PLAYER))) {
            String curr = _mBoard[i]; // Save the current number
            _mBoard[i] = HUMAN_PLAYER;
            if (checkWinner() == 2) {
              _mBoard[i] = COMPUTER_PLAYER;
              return;
            } else
              _mBoard[i] = curr;
          }
        }

        // Generate random move
        var count = 0;
        do {
          count = count + 1;
          move = rnd.nextInt(9);
          print("Computer random move is " + '$move');
        } while (
        (_mBoard[move] == HUMAN_PLAYER || _mBoard[move] == COMPUTER_PLAYER) &&
            (count < 9));

        if ((_mBoard[move] == HUMAN_PLAYER) || (_mBoard[move] == COMPUTER_PLAYER)) {
          return;
        } else {
          print("Computer is making a random moving to " + '$move');

          _mBoard[move] = COMPUTER_PLAYER;
        }
      }

      void displayMessage(String text) {
        setState(() {
          _text = text;
          print(_text);
        });
      }


      void checkGameOver(int win) {
        if (win == 1) {
          gameOver = true;
          displayMessage("It's a tie.");
        } else if (win == 2) {
          gameOver = true;
          displayMessage(HUMAN_PLAYER + " wins!");
        } else if (win == 3) {
          gameOver = true;
          displayMessage(COMPUTER_PLAYER + " wins!");
        }
      }

      void _newGame() {
        setState(() {
          for (int i = 0; i < BOARD_SIZE; i++) _mBoard[i] = "";
          win = 0;
          gameOver = false;
          turn = 0;
          _text = "X's Turn";
        });
      }

void _button0() {
            setState(() {
              if (_mBoard[0] == HUMAN_PLAYER || _mBoard[0] == COMPUTER_PLAYER) {
        //        _choice = "X";
                print("That space is occupied.  Please choose another space.");

                return;
              } else if (win == 0) {
                if (turn == 0) {
                  _mBoard[0] = HUMAN_PLAYER;
                  _text = HUMAN_PLAYER + " MOVED, O's TURN";

                  print("onTap called. card #0 was pressed");
                  turn = 1;
                  _mText = "X";
                  win = checkWinner();
                  checkGameOver(win);
                  displayBoard();
                }
                if ((turn == 1) && (win == 0)) {
                  turn = 0;
        //          _mText1 = "O";
                  computerTurn();
                  win = checkWinner();
                  checkGameOver(win);
                  displayBoard();
                }
              }
            });
          }

@override
          Widget build(BuildContext context) {
            return new Scaffold(
              appBar: new AppBar(
                  leading: new Icon(Icons.grid_on),
                  title: new Text("Tic Tac Toe"),
                  actions: <Widget>[
                    new IconButton(
                        icon: new Icon(Icons.new_releases),
                        onPressed: () {
                          _newGame();
                        }),

          body: new Container(
              padding: EdgeInsets.all(14.0),
              child: Column(
                  mainAxisAlignment: MainAxisAlignment.start,
                  children: <Widget>[
                    Row(
                      //Start of the 1st Row
                        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                        children: <Widget>[
                          // Button 0 in 1st Row
                          RaisedButton(
                            padding: const EdgeInsets.all(20.0),
                            onPressed: () {
                              _button0();
                            },
                            child: new Text(" ",
                                textAlign: TextAlign.center,
                                style: new TextStyle(
                                  fontWeight: FontWeight.bold,
                                  fontSize: 40.0,
                                  fontFamily: 'Roboto',
                                )),
                            color: Colors.grey[300],
                          ),

                          //Button 1 in 1st Row
                          RaisedButton(
                              padding: const EdgeInsets.all(20.0),
                              onPressed: () {
                                _button1();
                              },
                              child: new Text(" ",
                                  textAlign: TextAlign.center,
                                  style: new TextStyle(
                                    fontWeight: FontWeight.bold,
                                    fontSize: 40.0,
                                    fontFamily: 'Roboto',
                                  ))),

                          //Button 2 in 1st Row
                          RaisedButton(
                              padding: const EdgeInsets.all(20.0),
                              onPressed: () {
                                _button2();
                              },
                              child: new Text(" ",
                                  textAlign: TextAlign.center,
                                  style: new TextStyle(
                                    fontWeight: FontWeight.bold,
                                    fontSize: 40.0,
                                    fontFamily: 'Roboto',
                                  ))),
                        ]),
                    // end 1st Row



            Padding(padding: const EdgeInsets.all(7.0)),

                        Text(
                          //Info Label
                          _text,
                          textAlign: TextAlign.center,
                          overflow: TextOverflow.ellipsis,
                          style: TextStyle(fontWeight: FontWeight.bold, fontSize: 25.0),
                        ),

                        Padding(padding: const EdgeInsets.all(35.0)),

                        Row(
                          //Start of the New Game button Row
                            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                            children: <Widget>[
                              // New Game button
                              new RaisedButton(
                                  padding:
                                  const EdgeInsets.fromLTRB(50.0, 40.0, 50.0, 40.0),
                                  color: Colors.grey[400],
                                  onPressed: () {
                                    _newGame();
                                  },
                                  child: new Text("New Game",
                                      textAlign: TextAlign.center,
                                      style: new TextStyle(
                                        color: Colors.black,
                                        fontWeight: FontWeight.bold,
                                        fontSize: 20.0,
                                        fontFamily: 'Roboto',
                                      ))),
                            ])
                      ])),
            );
          }
        }