TicTacToe implementation (variable map size, win condition, players set)

TicTacToe.php

<?php

class TicTacToeGame
{
  /** @var int */
  private $width;
  /** @var int */
  private $height;
  /** @var int */
  private $winCond;
  /** @var array */
  private $players;
  private $currentPlayer = 0;
  private $turnsLeft;
  private $map           = [];
  private $winner        = null;
  private $isOver        = false;

  public function __construct($width = 3, $height = 3, $winCond = 3, $players = ['X', 'O'])
  {
    if ($winCond > min($width, $height)) throw new InvalidArgumentException('$win can not be greater than size');
    $this->width   = $width;
    $this->height  = $height;
    $this->winCond = $winCond;
    $this->players = $players;
    
    $this->start();
  }

  public function turn($i, $j)
  {
    if ($i < 0 or $i >= $this->width) throw new InvalidArgumentException('Invalid $i arg');
    if ($j < 0 or $j >= $this->height) throw new InvalidArgumentException('Invalid $j arg');
    if (!is_null($this->map[$j][$i])) throw new InvalidArgumentException('Field is busy!');;

    $this->map[$j][$i] = $this->currentPlayer;
    $this->turnsLeft--;

    if ($this->checkWin($i, $j)) {
      $this->winner = $this->currentPlayer;
      $this->isOver = true;
    } elseif ($this->turnsLeft <= 0) {
      // Draw
      $this->isOver = true;
    } else {
      $this->nextPlayer();
    }
  }

  private function nextPlayer()
  {
    $this->currentPlayer = ($this->currentPlayer + 1) % count($this->players);
  }

  public function getPlayer($player = null)
  {
    return $this->players[$player ?? $this->currentPlayer];
  }

  private function checkWin($i, $j)
  {
    $player = $this->map[$j][$i];

    //  '—' direction
    $count = 1;
    for ($ci = $i - 1; $this->map[$j][$ci] === $player; $ci--) $count++;
    for ($ci = $i + 1; $this->map[$j][$ci] === $player; $ci++) $count++;
    if ($count >= $this->winCond) return true;

    //  '|' direction
    $count = 1;
    for ($cj = $j - 1; $this->map[$cj][$i] === $player; $cj--) $count++;
    for ($cj = $j + 1; $this->map[$cj][$i] === $player; $cj++) $count++;
    if ($count >= $this->winCond) return true;

    //  '\' direction
    $count = 1;
    for ($ci = $i - 1, $cj = $j - 1; $this->map[$cj][$ci] === $player; $ci--, $cj--) $count++;
    for ($ci = $i + 1, $cj = $j + 1; $this->map[$cj][$ci] === $player; $ci++, $cj++) $count++;
    if ($count >= $this->winCond) return true;

    //  '/' direction
    $count = 1;
    for ($ci = $i - 1, $cj = $j + 1; $this->map[$cj][$ci] === $player; $ci--, $cj++) $count++;
    for ($ci = $i + 1, $cj = $j - 1; $this->map[$cj][$ci] === $player; $ci++, $cj--) $count++;
    if ($count >= $this->winCond) return true;

    return false;
  }

  public function render()
  {
    echo '<table border="1">';
    foreach ($this->map as $j => $row) {
      echo '<tr>';
      foreach ($row as $i => $cell) {
        echo "<td width='30' onclick='location=\"?i={$i}&j={$j}\"'>";
        echo is_null($cell) ? '&nbsp;' : $this->players[$cell];
        echo "</td>";
      }
      echo '</tr>';
    }
    echo '</table>';

    echo '<hr>';
    ?>
    <form action="">
      <input type="text" name="width" title="Width" placeholder="width" value="<?= $this->width ?>">
      <input type="text" name="height" title="Height" placeholder="height" value="<?= $this->height ?>">
      <input type="text" name="winCond" title="WinCond" placeholder="winCond" value="<?= $this->winCond ?>">
      <input type="text" name="players" title="Players" placeholder="players"
             value="<?= implode(',', $this->players) ?>">
      <input type="submit" name="reset">
    </form>
    <?php

    echo 'Turn of ' . $this->getPlayer();

  }

  public function getWinner()
  {
    return $this->winner;
  }
  public function isOver()
  {
    return $this->isOver;
  }
  public function start()
  {
    $this->isOver        = false;
    $this->winner        = null;
    $this->currentPlayer = 0;
    $this->turnsLeft     = $this->width * $this->height;

    for ($j = 0; $j < $this->height; $j++) {
      $this->map[$j] = [];
      for ($i = 0; $i < $this->width; $i++) {
        $this->map[$j][$i] = null;
      }
    }
  }
}

session_start();

if (empty($_SESSION['game']) || array_key_exists('reset', $_GET)) {
  $width   = $_GET['width'] ?? 3;
  $height  = $_GET['height'] ?? 3;
  $cond    = $_GET['winCond'] ?? 3;
  $players = isset($_GET['players']) ? explode(',', $_GET['players']) : ['X', 'O'];
  // start game
  $game             = new TicTacToeGame($width, $height, $cond, $players);
  $_SESSION['game'] = $game;
  echo 'Game started<br>';
} else {
  /** @var TicTacToeGame $game */
  $game = &$_SESSION['game'];
  if ($game->isOver()) {
    $game->start();
  }

  if (!isset($_GET['i'], $_GET['j'])) {
    echo 'Pass coords: i, j!<br>';
  } else {
    // turn
    try {
      $game->turn($_GET['i'], $_GET['j']);
      if ($game->isOver()) {
        echo "Game is over!<br/>";
        $winner = $game->getWinner();
        if (is_null($winner)) {
          echo "Draw!<br/>";
        } else {
          echo $game->getPlayer($winner) . " Win!<br/>";
        }
      }
    } catch (InvalidArgumentException $e) {
      echo $e->getMessage(), '<br/>';
    }
  }
}

$game->render();