1: <?php
 2: /**
 3:  * Wei Framework
 4:  *
 5:  * @copyright   Copyright (c) 2008-2013 Twin Huang
 6:  * @license     http://opensource.org/licenses/mit-license.php MIT License
 7:  */
 8: 
 9: namespace Wei\Validator;
10: 
11: /**
12:  * Check if the input is valid by the Luhn algorithm
13:  *
14:  * @author      Twin Huang <twinhuang@qq.com>
15:  */
16: class Luhn extends BaseValidator
17: {
18:     protected $invalidMessage = '%name% is not a valid number';
19: 
20:     /**
21:      * {@inheritdoc}
22:      */
23:     protected function doValidate($input)
24:     {
25:         if (!$this->isString($input)) {
26:             $this->addError('notString');
27:             return false;
28:         }
29: 
30:         $checksum = $this->getChecksum(substr($input, 0, -1));
31:         if ($checksum != substr($input, -1)) {
32:             return false;
33:         }
34: 
35:         return true;
36:     }
37: 
38:     /**
39:      * Return the checksum char of luhn algorithm
40:      *
41:      * @param string $string
42:      * @return string
43:      */
44:     protected function getChecksum($string)
45:     {
46:         $checksum = '';
47:         foreach (str_split(strrev($string)) as $i => $d) {
48:             $checksum .= ($i % 2 === 0) ? ($d * 2) : $d;
49:         }
50:         return (10 - array_sum(str_split($checksum)) % 10) % 10;
51:     }
52: }
53: