Scrambler.php

<?php

class Scrambler
{
    private $faces = array('U', 'D', 'L', 'R', 'F', 'B');
    
    public function __construct()
    {
        $this->length = 25;
        $this->chance_prime = 25;
        $this->chance_double = 35;
    }
    
    public function setLength($value)
    {
        $this->length = $value;
    }
    
    public function setChancePrime($value)
    {
        $this->chance_prime = $value;
    }
    
    public function setChanceDouble($value)
    {
        $this->chance_double = $value;
    }
    
    public function generate()
    {
        $last = null;
        do {
            $move = $this->faces[array_rand($this->faces)];
            if ($move != $last) {
                $last = $move;
                $rand = mt_rand(0, 100);
                if ($rand <= $this->chance_prime) {
                    $move .= "'";
                } elseif ($rand <= $this->chance_prime + $this->chance_double) {
                    $move .= '2';
                }
                $scramble[] = $move;
            }
        } while (count($scramble) < $this->length);
        return implode(' ', $scramble);
    }
}