<?php

/**
 * Generic class for compressing website sourcecode.
 *
 * This class requires PHP 5.
 *
 * Copyright 2009 by Simon Wippich, www.wippich.org
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 *
 * @version 1.0
 * @author Simon Wippich <development@wippich.org>
 * @copyright Copyright (c) 2009, Simon Wippich
 * @license http://www.gnu.org/licenses/ GNU Lesser General Public License
 */
class Qs_Packer_Html
{
    /**
     * Method for compressing HTML-sourcecode.
     *
     * @access public
     * @param $htmlSourceCode String The original HTML-sourcecode
     * @param $removeComments bool
     * @return String The compressed HTML-sourcecode
     * @throws Exception
     */
    final public static function compressHtml($htmlSourceCode, $removeComments = true)
    {
        // Initialize a returning variable
        $returnValue = '';
        try {
            // Check if the given parameter matches datatype string
            if (is_string($htmlSourceCode)) {
                // Exclude pre- or code-tags
                preg_match_all(
                    '!(<(?:code|pre|textarea).*>[^<]+</(?:code|pre|textarea)>)!',
                    $htmlSourceCode,
                    $pre
                );
                // Remove all pre- or code-tags
                $htmlSourceCode = preg_replace(
                    '!<(?:code|pre|textarea).*>[^<]+</(?:code|pre|textarea)>!',
                    '#pre#',
                    $htmlSourceCode
                );
                // Exclude all value attributes
                preg_match_all(
                    '!((?:value=\")[^\"]*(?:\"))!',
                    $htmlSourceCode,
                    $value
                );
                // Remove all value attributes
                $htmlSourceCode = preg_replace(
                    '!((?:value=\")[^\"]*(?:\"))!',
                    '#value#',
                    $htmlSourceCode
                );
                // Remove HTML-comments if required
                if ($removeComments === true) {
                    $htmlSourceCode = preg_replace(
                        '/\<!--[^\[][^\>]*--\>/',
                        '',
                        $htmlSourceCode
                    );
                }
                // Remove new lines, spaces and tabs
                $htmlSourceCode = preg_replace(
                    '/[\r\n\t]+/',
                    ' ',
                    $htmlSourceCode
                );
                $htmlSourceCode = preg_replace(
                    '/>[\s]+</',
                    '> <',
                    $htmlSourceCode
                );
                $htmlSourceCode = preg_replace(
                    '/[\s]+/',
                    ' ',
                    $htmlSourceCode
                );
                if (!empty($pre[0])) {
                    foreach ($pre[0] as $tag) {
                        // Return pre- and code-tags
                        $tag = str_replace(array('\\', '$'), array('\\\\', '\$'), $tag);
                        $htmlSourceCode = preg_replace(
                            '!#pre#!',
                            $tag,
                            $htmlSourceCode,
                            1
                        );
                    }
                }
                if (!empty($value[0])) {
                    foreach ($value[0] as $attribute) {
                        // Return value attributes
                        $attribute = str_replace(array('\\', '$'), array('\\\\', '\$'), $attribute);
                        $htmlSourceCode = preg_replace(
                            '!#value#!',
                            $attribute,
                            $htmlSourceCode,
                            1
                        );
                    }
                }
                // Remove preceding and trailing spaces and write
                // the processed sourcecode into the returning variable
                $returnValue = trim($htmlSourceCode);
                // Delete the original sourcecode
                unset($htmlSourceCode);
            } else {
                // Throw an exception in case of an invalid method parameter
                throw new Exception(
                    'Method "'
                    . __FUNCTION__
                    . '" of class "CodeCompressor" reported an error: '
                    .  'Invalid parameter!'
                );
            }
        } catch(Exception $e) {
            // Catch all occuring exceptions form the preceding codeblock
            // and write the errormessages into the returning variable
            $returnValue = $e->getMessage();
        }
        // Return the filled variable
        return $returnValue;
    }
}