A Tic-Tac-Toe game for any square board and any number of players

tic-tac-toe.php

<?php

class TicTacToe {
  /**
   * Board for the game
   * @var array
   */
   private $board = [];

   /**
    * The size of the board
    * @var integer
    */
   private $size = 0;

   /**
    * The size of the square board, (number of rows)
    * @var integer
    */
   private $square = 0;

  /**
   * Tiles used on the game
   * @var array
   */
  private $turnTiles = ['x','o'];

  /**
   * Strings for tiles winning lines, ex: 'xxx'
   * @var array
   */
  private $tilesStr = [];

  /**
   * Colors used for each tile
   * @var array
   */
  private $turnColors = [31, 32];

  /**
   * Array with the Winning combinations
   * @var array
   */
  private $winningLines = [];

  /**
   * Winning combinations ordered by position
   * @var array
   */
  private $winningByPos = [];

  /**
   * Gamer turn, in case of two players: 0 first player, and 1 second player
   * @var integer
   */
  private $turn = 0;

  /**
   * Initialize the default values for the game
   * @param integer $size
   * @param array   $tiles
   */
  function __construct($size = 9, $tiles = ['x', 'o']){
    $this->size = $size;
    $this->square = sqrt($size);
    $this->board = range(1, $size);
    $this->generateWinningLines();
    $this->turnTiles = $tiles;
    foreach ($this->turnTiles as $tile) {
      $this->tilesStr[] = str_repeat($tile, $this->square);
    }
  }

  /**
   * Generate the winning lines for a square board
   * @return null
   */
  private function generateWinningLines() {
    $lines = [];

    // Horizontal and vertical
    for($c = 0, $r = 0; $c < $this->square; $c++, $r+=$this->square) {
      $lines[] = range($c, $this->size-1, $this->square);
      $lines[] = range($r, ($c+1)*$this->square-1);
    }

    // Diagonal
    $lines[] = range($this->square-1, $this->size-2, $this->square-1);
    $lines[] = range(0, $this->size, $this->square+1);

    $this->winningLines = $lines;

    // Order winning lines by pos to improve performance on each turn
    foreach($lines as $line) {
      foreach ($line as $pos) {
        $winningByPos[$pos][] = $line;
      }
    }

    $this->winningByPos = $winningByPos;
  }

  /**
   * Get the color according to the tile
   * @param  string $tile
   * @return integer The color number
   */
  private function getColorByTile($tile) {
    $color = 0;
    $c = array_search($tile, $this->turnTiles);
    if($c !== false) {
      $color = $this->turnColors[$c];
    }

    return $color;
  }

  /**
   * Draw the board on the console
   * @return null
   */
  private function drawBoard() {
    echo "\n";
    foreach($this->board as $k => $place) {
      $color = $this->getColorByTile($place);
      echo "| \033[0;{$color}m{$place}\033[0m ";
      if(($k+1) % $this->square == 0){
        echo "|\n";
      }
    }
    echo "\n";
  }

  /**
   * Validate if the given position is valid
   * @param  string  $pos
   * @return boolean true in case is valid
   */
  private function isValidPos($pos) {
    if ($pos < 1 || $pos > $this->size) {
      echo "The position is not valid\n";
      return false;
    }
    $pos = $pos-1;
    if (in_array($this->board[$pos], $this->turnTiles)) {
      echo "The position is already taked\n";
      return false;
    }

    return true;
  }

  /**
   * Ask for the position to put the new tile and validate if that gives the win
   * @return boolean true if the game end by win
   */
  private function playTurn() {
    do {
      echo "Is the turn for \033[0;{$this->turnColors[$this->turn]}m{$this->turnTiles[$this->turn]}\033[0m \n";
      $place = readline("Select the position: ");
    } while(!$this->isValidPos($place));

    $this->board[$place-1] = $this->turnTiles[$this->turn];
    $isWin = $this->checkWin($place);

    return $isWin;
  }

  /**
   * Validate if the last movement gives the win
   * @param  integer $pos The position of the last movement
   * @return boolean      True if a line is formed to win
   */
  private function checkWin($pos) {
    $pos = $pos-1;

    foreach($this->winningByPos[$pos] as $line) {
      $t = implode($this->getBoardLine($line));
      if(in_array($t, $this->tilesStr)) {
        return true;
      }
    }
    return false;
  }

  /**
   * Get a board line, used to get the lines from winning
   * @param  array $line Array with the positions for the line
   * @return array
   */
  private function getBoardLine($line) {
    foreach($line as $k) {
      $l[] = $this->board[$k];
    }
    return $l;
  }

  /**
   * Display message for winner
   * @return null
   */
  private function showWinner() {
    echo "Congratulations!! \033[0;{$this->turnColors[$this->turn]}m{$this->turnTiles[$this->turn]}\033[0m won!\n";
  }

  /**
   * Display message for draw
   * @return null
   */
  private function showTie() {
    echo "The game is a draw!\n";
  }

  /**
   * The main functionality for the tic tac toe game
   * @return null
   */
  public function run() {
    $this->turn = 0;
    $round = 0;
    $win = false;
    $this->drawBoard();

    do {
      $win = $this->playTurn();
      $this->drawBoard();
      if($win) {
        $this->showWinner();
        break;
      }
      $this->turn = ($this->turn+1)%count($this->turnTiles);
      $round++;
    } while (!$win && $round < $this->size);

    if ($round >= $this->size){
      $this->showTie();
    }
  }
}

$game = new TicTacToe();
$game->run();