php/external/Zend/Validate/Ccnum.php

<?php

/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Validate
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Ccnum.php 8064 2008-02-16 10:58:39Z thomas $
 */

/**
 * @see Zend_Validate_Abstract
 */
require_once 'external/Zend/Validate/Abstract.php';

/**
 * @category   Zend
 * @package    Zend_Validate
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Validate_Ccnum extends Zend_Validate_Abstract {
  /**
   * Validation failure message key for when the value is not of valid length
   */
  const LENGTH = 'ccnumLength';
  
  /**
   * Validation failure message key for when the value fails the mod-10 checksum
   */
  const CHECKSUM = 'ccnumChecksum';
  
  /**
   * Digits filter for input
   *
   * @var Zend_Filter_Digits
   */
  protected static $_filter = null;
  
  /**
   * Validation failure message template definitions
   *
   * @var array
   */
  protected $_messageTemplates = array(self::LENGTH => "'%value%' must contain between 13 and 19 digits", 
      self::CHECKSUM => "Luhn algorithm (mod-10 checksum) failed on '%value%'");

  /**
   * Defined by Zend_Validate_Interface
   *
   * Returns true if and only if $value follows the Luhn algorithm (mod-10 checksum)
   *
   * @param  string $value
   * @return boolean
   */
  public function isValid($value) {
    $this->_setValue($value);
    
    if (null === self::$_filter) {
      /**
       * @see Zend_Filter_Digits
       */
      require_once 'external/Zend/Filter/Digits.php';
      self::$_filter = new Zend_Filter_Digits();
    }
    
    $valueFiltered = self::$_filter->filter($value);
    
    $length = strlen($valueFiltered);
    
    if ($length < 13 || $length > 19) {
      $this->_error(self::LENGTH);
      return false;
    }
    
    $sum = 0;
    $weight = 2;
    
    for ($i = $length - 2; $i >= 0; $i --) {
      $digit = $weight * $valueFiltered[$i];
      $sum += floor($digit / 10) + $digit % 10;
      $weight = $weight % 2 + 1;
    }
    
    if ((10 - $sum % 10) % 10 != $valueFiltered[$length - 1]) {
      $this->_error(self::CHECKSUM, $valueFiltered);
      return false;
    }
    
    return true;
  }

}