<?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) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 * @version    $Id: Issn.php 20785 2010-01-31 09:43:03Z mikaelkael $

 */

/**

 * @see Zend_Validate_Barcode_AdapterAbstract

 */

require_once 'Zend/Validate/Barcode/AdapterAbstract.php';

/**

 * @category   Zend

 * @package    Zend_Validate

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

class Zend_Validate_Barcode_Issn extends Zend_Validate_Barcode_AdapterAbstract

{

    /**

     * Allowed barcode lengths

     * @var integer

     */

    protected $_length = array(8, 13);

    /**

     * Allowed barcode characters

     * @var string

     */

    protected $_characters = '0123456789X';

    /**

     * Checksum function

     * @var string

     */

    protected $_checksum = '_gtin';

    /**

     * Allows X on length of 8 chars

     *

     * @param  string $value The barcode to check for allowed characters

     * @return boolean

     */

    public function checkChars($value)

    {

        if (strlen($value) != 8) {

            if (strpos($value, 'X') !== false) {

                return false;

            }

        }

        return parent::checkChars($value);

    }

    /**

     * Validates the checksum

     *

     * @param  string $value The barcode to check the checksum for

     * @return boolean

     */

    public function checksum($value)

    {

        if (strlen($value) == 8) {

            $this->_checksum = '_issn';

        } else {

            $this->_checksum = '_gtin';

        }

        return parent::checksum($value);

    }

    /**

     * Validates the checksum ()

     * ISSN implementation (reversed mod11)

     *

     * @param  string $value The barcode to validate

     * @return boolean

     */

    protected function _issn($value)

    {

        $checksum = substr($value, -1, 1);

        $values   = str_split(substr($value, 0, -1));

        $check    = 0;

        $multi    = 8;

        foreach($values as $token) {

            if ($token == 'X') {

                $token = 10;

            }

            $check += ($token * $multi);

            --$multi;

        }

        $check %= 11;

        $check  = 11 - $check;

        if ($check == $checksum) {

            return true;

        } else if (($check == 10) && ($checksum == 'X')) {

            return true;

        }

        return false;

    }

}