Enigma M3 Machine in PHP

Enigma.php

<?php namespace Enigma;

class Reflector {
  protected $table;

  public function __construct($table) {
    $this->table = array_combine(range('A', 'Z'), str_split($table));
  }

  public function convert($character) {
    return $this->table[$character];
  } 

  public static function select($type) {
    switch ($type) {
      case 'A':
        return new static('EJMZALYXVBWFCRQUONTSPIKHGD');
      case 'B':
        return new static('YRUHQSLDPXNGOKMIEBFZCWVJAT');
      case 'C':
        return new static('FVPJIAOYEDRZXWGCTKUQSBNMHL');
    }

    throw new \InvalidArgumentException('Invalid Reflector');
  }
}

class Plugboard {
  protected $plugs;

  public function __construct(array $plugs) {
    $this->plugs = $plugs + array_flip($plugs);
  }

  public function convert($character) {
    return isset($this->plugs[$character]) ?
      $this->plugs[$character] : $character;
  }
}

class Rotor {
  protected $table;
  protected $notch;

  public function __construct($table, array $notch) {
    $this->table = array_combine(range('A', 'Z'), str_split($table));
    $this->notch = $notch;
  }

  public function step() {
    $keys = array_keys($this->table);
    array_unshift($keys, array_pop($keys));

    $vals = array_map(function($c) {
      $i = ord($c) - 1;
      return $i < 65 ? 'Z' : chr($i);
    }, array_values($this->table));

    $this->table = array_combine($keys, $vals);
  }

  public function set($character) {
    for ($i = 0; $i < ord($character) - 65; $i++)
      $this->step();
  }

  public function notched() {
    return in_array(current($this->table), $this->notch);
  }

  public function in($character) {
    return $this->table[$character];
  }

  public function out($character) {
    return array_flip($this->table)[$character];
  }

  public static function select($type) {
    switch ($type) {
      case 'I':
          return new static('EKMFLGDQVZNTOWYHXUSPAIBRCJ', ['Q']);
      case 'II':
          return new static('AJDKSIRUXBLHWTMCQGZNPYFVOE', ['E']);
      case 'III':
          return new static('BDFHJLCPRTXVZNYEIWGAKMUSQO', ['V']);
      case 'IV':
          return new static('ESOVPZJAYQUIRHXLNFTGKDCMWB', ['J']);
      case 'V':
          return new static('VZBRGITYUPSDNHLXAWMJQOFECK', ['Z']);
      case 'VI':
          return new static('JPGVOUMFYQBENHZRDKASXLICTW', ['Z', 'M']);
      case 'VII':
          return new static('NZJHGRCXMYSWBOUFAIVLPEKQDT', ['Z', 'M']);
      case 'VII':
          return new static('FKQHTLXOCBJSPDZRAMEWNIUYGV', ['Z', 'M']);
    }

    throw new \InvalidArgumentException('Invalid Rotor');    
  }
}

class Rotors {
  protected $rotors;

  public function __construct(...$rotors) {
    $this->rotors = array_reverse($rotors);
  }

  public function step() {
    reset($this->rotors);
    do {
      current($this->rotors)->step();
    } while (next($this->rotors)->notched());
  }

  public function in($character) {
    foreach ($this->rotors as $rotor)
      $character = $rotor->in($character);
    return $character;
  }

  public function out($character) {
    foreach (array_reverse($this->rotors) as $rotor)
      $character = $rotor->out($character);
    return $character;
  }
}

class Machine {
  protected $plugboard;
  protected $reflector;
  protected $rotors;

  public function __construct($plugboard, $reflector, $rotors) {
    $this->plugboard = $plugboard;
    $this->reflector = $reflector;
    $this->rotors    = $rotors;
  }

  protected function clean($text) {
    return preg_replace('/[^A-Z]/', '', strtoupper($text));
  }

  public function convert($text) {
    $output = '';

    foreach (str_split($this->clean($text)) as $c) {
      $this->rotors->step();
      $c = $this->plugboard->convert($c);
      $c = $this->rotors->in($c);
      $c = $this->reflector->convert($c);
      $c = $this->rotors->out($c);
      $c = $this->plugboard->convert($c);

      $output .= $c;
    }

    return $output;
  }
}

// example usage.

$plugboard = new Plugboard(['H' => 'F']);

$reflector = Reflector::select('B');

$i   = Rotor::select('I');
$ii  = Rotor::select('II');
$iii = Rotor::select('III');

$i->set('B');
$ii->set('B');
$iii->set('B');

$rotors = new Rotors($i, $ii, $iii);

$machine = new Machine($plugboard, $reflector, $rotors);

echo $machine->convert('ATTACKATDAWN');