php/external/Zend/Validate/Barcode/UpcA.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: UpcA.php 8210 2008-02-20 14:09:05Z andries $
 */

/**
 * @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_Barcode_UpcA extends Zend_Validate_Abstract {
  /**
   * Validation failure message key for when the value is
   * an invalid barcode
   */
  const INVALID = 'invalid';
  
  /**
   * Validation failure message key for when the value is
   * not 12 characters long
   */
  const INVALID_LENGTH = 'invalidLength';
  
  /**
   * Validation failure message template definitions
   *
   * @var array
   */
  protected $_messageTemplates = array(self::INVALID => "'%value%' is an invalid UPC-A barcode", 
      self::INVALID_LENGTH => "'%value%' should be 12 characters");

  /**
   * Defined by Zend_Validate_Interface
   *
   * Returns true if and only if $value contains a valid barcode
   *
   * @param  string $value
   * @return boolean
   */
  public function isValid($value) {
    $valueString = (string)$value;
    $this->_setValue($valueString);
    
    if (strlen($valueString) !== 12) {
      $this->_error(self::INVALID_LENGTH);
      return false;
    }
    
    $barcode = substr($valueString, 0, - 1);
    $oddSum = 0;
    $evenSum = 0;
    
    for ($i = 0; $i < 11; $i ++) {
      if ($i % 2 === 0) {
        $oddSum += $barcode[$i] * 3;
      } elseif ($i % 2 === 1) {
        $evenSum += $barcode[$i];
      }
    }
    
    $calculation = ($oddSum + $evenSum) % 10;
    $checksum = ($calculation === 0) ? 0 : 10 - $calculation;
    
    if ($valueString[11] != $checksum) {
      $this->_error(self::INVALID);
      return false;
    }
    
    return true;
  }
}