<?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_Dom

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

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

 */

/**

 * Transform CSS selectors to XPath

 *

 * @package    Zend_Dom

 * @subpackage Query

 * @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: Css2Xpath.php 22044 2010-04-28 19:58:29Z matthew $

 */

class Zend_Dom_Query_Css2Xpath

{

    /**

     * Transform CSS expression to XPath

     *

     * @param  string $path

     * @return string

     */

    public static function transform($path)

    {

        $path = (string) $path;

        if (strstr($path, ',')) {

            $paths       = explode(',', $path);

            $expressions = array();

            foreach ($paths as $path) {

                $xpath = self::transform(trim($path));

                if (is_string($xpath)) {

                    $expressions[] = $xpath;

                } elseif (is_array($xpath)) {

                    $expressions = array_merge($expressions, $xpath);

                }

            }

            return implode('|', $expressions);

        }

        $paths    = array('//');

        $path     = preg_replace('|\s+>\s+|', '>', $path);

        $segments = preg_split('/\s+/', $path);

        foreach ($segments as $key => $segment) {

            $pathSegment = self::_tokenize($segment);

            if (0 == $key) {

                if (0 === strpos($pathSegment, '[contains(')) {

                    $paths[0] .= '*' . ltrim($pathSegment, '*');

                } else {

                    $paths[0] .= $pathSegment;

                }

                continue;

            }

            if (0 === strpos($pathSegment, '[contains(')) {

                foreach ($paths as $key => $xpath) {

                    $paths[$key] .= '//*' . ltrim($pathSegment, '*');

                    $paths[]      = $xpath . $pathSegment;

                }

            } else {

                foreach ($paths as $key => $xpath) {

                    $paths[$key] .= '//' . $pathSegment;

                }

            }

        }

        if (1 == count($paths)) {

            return $paths[0];

        }

        return implode('|', $paths);

    }

    /**

     * Tokenize CSS expressions to XPath

     *

     * @param  string $expression

     * @return string

     */

    protected static function _tokenize($expression)

    {

        // Child selectors

        $expression = str_replace('>', '/', $expression);

        // IDs

        $expression = preg_replace('|#([a-z][a-z0-9_-]*)|i', '[@id=\'$1\']', $expression);

        $expression = preg_replace('|(?<![a-z0-9_-])(\[@id=)|i', '*$1', $expression);

        // arbitrary attribute strict equality

        $expression = preg_replace_callback(

            '|\[([a-z0-9_-]+)=[\'"]([^\'"]+)[\'"]\]|i',

            array(__CLASS__, '_createEqualityExpression'),

            $expression

        );

        // arbitrary attribute contains full word

        $expression = preg_replace_callback(

            '|\[([a-z0-9_-]+)~=[\'"]([^\'"]+)[\'"]\]|i',

            array(__CLASS__, '_normalizeSpaceAttribute'),

            $expression

        );

        // arbitrary attribute contains specified content

        $expression = preg_replace_callback(

            '|\[([a-z0-9_-]+)\*=[\'"]([^\'"]+)[\'"]\]|i',

            array(__CLASS__, '_createContainsExpression'),

            $expression

        );

        // Classes

        $expression = preg_replace(

            '|\.([a-z][a-z0-9_-]*)|i', 

            "[contains(concat(' ', normalize-space(@class), ' '), ' \$1 ')]", 

            $expression

        );

        /** ZF-9764 -- remove double asterix */

        $expression = str_replace('**', '*', $expression);

        return $expression;

    }

    /**

     * Callback for creating equality expressions

     * 

     * @param  array $matches 

     * @return string

     */

    protected static function _createEqualityExpression($matches)

    {

        return '[@' . strtolower($matches[1]) . "='" . $matches[2] . "']";

    }

    /**

     * Callback for creating expressions to match one or more attribute values

     * 

     * @param  array $matches 

     * @return string

     */

    protected static function _normalizeSpaceAttribute($matches)

    {

        return "[contains(concat(' ', normalize-space(@" . strtolower($matches[1]) . "), ' '), ' " 

             . $matches[2] . " ')]";

    }

    /**

     * Callback for creating a strict "contains" expression

     * 

     * @param  array $matches 

     * @return string

     */

    protected static function _createContainsExpression($matches)

    {

        return "[contains(@" . strtolower($matches[1]) . ", '" 

             . $matches[2] . "')]";

    }

}