// https://thecodingtrain.com/CodingChallenges/149-tic-tac-toe.html

// https://youtu.be/GTWrWM1UsnA

// https://editor.p5js.org/codingtrain/sketches/5JngATm3c

​

let game_over = false;

​

let board = [

  [null, null, null],

  [null, null, null],

  [null, null, null],

];

​

let players = [{

    _class: Cross,

    symbol: Cross.symbol

  },

  {

    _class: Circle,

    symbol: Circle.symbol

  }

];

​

let currentPlayer;

let available = [];

let winning_line = null;

​

function setup() {

  createCanvas(400, 400);

  frameRate(60);

  currentPlayer = floor(random(players.length));

  for (let j = 0; j < 3; j++) {

    for (let i = 0; i < 3; i++) {

      available.push([i, j]);

    }

  }

  nextTurn();

  setInterval(nextTurn, 500);

}

​

function equals3(a, b, c) {

  return (a && b && c && // Check for null

    a.symbol == b.symbol && b.symbol == c.symbol); // Check they're equal

}

​

function place_winning_line(a, b) {

  winning_line = new WinningLine(

    a.getCenter(),

    b.getCenter()

  );

}

​

function checkWinner() {

  let winner = null;

​

  // horizontal

  for (let i = 0; i < 3; i++) {

    if (equals3(board[i][0], board[i][1], board[i][2])) {

      winner = board[i][0].symbol;

      place_winning_line(board[i][0], board[i][2]);

    }

  }

​

  // Vertical

  for (let i = 0; i < 3; i++) {

    if (equals3(board[0][i], board[1][i], board[2][i])) {

      winner = board[0][i].symbol;

      place_winning_line(board[0][i], board[2][i]);

    }

  }

​

  // Diagonal

  if (equals3(board[0][0], board[1][1], board[2][2])) {

    winner = board[0][0].symbol;

    place_winning_line(board[0][0], board[2][2]);

  }

  if (equals3(board[2][0], board[1][1], board[0][2])) {

    winner = board[2][0].symbol;

    place_winning_line(board[2][0], board[0][2]);

  }

​

  if (winner == null && available.length == 0) {

    return 'tie';

  } else {

    return winner;

  }

​

}

​

function nextTurn() {

  if (game_over) return;

  let index = floor(random(available.length));

  let spot = available.splice(index, 1)[0];

  let i = spot[0];

  let j = spot[1];

  board[i][j] = new players[currentPlayer]._class(i, j, width / 6);

  currentPlayer = (currentPlayer + 1) % players.length;

}

​

function mousePressed() {

  nextTurn();

}

​

function draw() {

  background(255);

  let w = width / 3;

  let h = height / 3;

  strokeWeight(4);

​

  stroke(0);

  line(w, 0, w, height);

  line(w * 2, 0, w * 2, height);

  line(0, h, width, h);

  line(0, h * 2, width, h * 2);

​

  for (let j = 0; j < 3; j++) {

    for (let i = 0; i < 3; i++) {

      let x = w * i + w / 2;

      let y = h * j + h / 2;

      let spot = board[i][j];

      textSize(32);

      if (spot) spot.draw();

    }

  }

​

  if (winning_line) winning_line.draw();

​

  if (!game_over) {

    let result = checkWinner();

    if (result != null) {

      game_over = true;

      let resultP = createP('');

      resultP.style('font-size', '32pt');

      if (result == 'tie') {

        resultP.html("Tie!")

      } else {

        resultP.html(`${result} wins!`);

      }

    }

  }

​

}