Merge "Typo fix"

[mediawiki.git] / includes / libs / CSSMin.php

<?php
/**
 * Minification of CSS stylesheets.
 *
 * Copyright 2010 Wikimedia Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *              http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed
 * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
 * OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 *
 * @file
 * @version 0.1.1 -- 2010-09-11
 * @author Trevor Parscal <tparscal@wikimedia.org>
 * @copyright Copyright 2010 Wikimedia Foundation
 * @license http://www.apache.org/licenses/LICENSE-2.0
 */

/**
 * Transforms CSS data
 *
 * This class provides minification, URL remapping, URL extracting, and data-URL embedding.
 */
class CSSMin {

        /* Constants */

        /**
         * Maximum file size to still qualify for in-line embedding as a data-URI
         *
         * 24,576 is used because Internet Explorer has a 32,768 byte limit for data URIs,
         * which when base64 encoded will result in a 1/3 increase in size.
         */
        const EMBED_SIZE_LIMIT = 24576;
        const URL_REGEX = 'url\(\s*[\'"]?(?P<file>[^\?\)\'"]*)(?P<query>\??[^\)\'"]*)[\'"]?\s*\)';

        /* Protected Static Members */

        /** @var array List of common image files extensions and mime-types */
        protected static $mimeTypes = array(
                'gif' => 'image/gif',
                'jpe' => 'image/jpeg',
                'jpeg' => 'image/jpeg',
                'jpg' => 'image/jpeg',
                'png' => 'image/png',
                'tif' => 'image/tiff',
                'tiff' => 'image/tiff',
                'xbm' => 'image/x-xbitmap',
        );

        /* Static Methods */

        /**
         * Gets a list of local file paths which are referenced in a CSS style sheet
         *
         * @param string $source CSS data to remap
         * @param string $path File path where the source was read from (optional)
         * @return array List of local file references
         */
        public static function getLocalFileReferences( $source, $path = null ) {
                $files = array();
                $rFlags = PREG_OFFSET_CAPTURE | PREG_SET_ORDER;
                if ( preg_match_all( '/' . self::URL_REGEX . '/', $source, $matches, $rFlags ) ) {
                        foreach ( $matches as $match ) {
                                $file = ( isset( $path )
                                        ? rtrim( $path, '/' ) . '/'
                                        : '' ) . "{$match['file'][0]}";

                                // Only proceed if we can access the file
                                if ( !is_null( $path ) && file_exists( $file ) ) {
                                        $files[] = $file;
                                }
                        }
                }
                return $files;
        }

        /**
         * @param $file string
         * @return bool|string
         */
        protected static function getMimeType( $file ) {
                $realpath = realpath( $file );
                // Try a couple of different ways to get the mime-type of a file, in order of
                // preference
                if (
                        $realpath
                        && function_exists( 'finfo_file' )
                        && function_exists( 'finfo_open' )
                        && defined( 'FILEINFO_MIME_TYPE' )
                ) {
                        // As of PHP 5.3, this is how you get the mime-type of a file; it uses the Fileinfo
                        // PECL extension
                        return finfo_file( finfo_open( FILEINFO_MIME_TYPE ), $realpath );
                } elseif ( function_exists( 'mime_content_type' ) ) {
                        // Before this was deprecated in PHP 5.3, this was how you got the mime-type of a file
                        return mime_content_type( $file );
                } else {
                        // Worst-case scenario has happened, use the file extension to infer the mime-type
                        $ext = strtolower( pathinfo( $file, PATHINFO_EXTENSION ) );
                        if ( isset( self::$mimeTypes[$ext] ) ) {
                                return self::$mimeTypes[$ext];
                        }
                }
                return false;
        }

        /**
         * Remaps CSS URL paths and automatically embeds data URIs for URL rules
         * preceded by an /* @embed * / comment
         *
         * @param string $source CSS data to remap
         * @param string $local File path where the source was read from
         * @param string $remote URL path to the file
         * @param bool $embedData If false, never do any data URI embedding, even if / * @embed * / is found
         * @return string Remapped CSS data
         */
        public static function remap( $source, $local, $remote, $embedData = true ) {
                $pattern = '/((?P<embed>\s*\/\*\s*\@embed\s*\*\/)(?P<pre>[^\;\}]*))?' .
                        self::URL_REGEX . '(?P<post>[^;]*)[\;]?/';
                $offset = 0;
                while ( preg_match( $pattern, $source, $match, PREG_OFFSET_CAPTURE, $offset ) ) {
                        // Skip fully-qualified URLs and data URIs
                        $urlScheme = parse_url( $match['file'][0], PHP_URL_SCHEME );
                        if ( $urlScheme ) {
                                // Move the offset to the end of the match, leaving it alone
                                $offset = $match[0][1] + strlen( $match[0][0] );
                                continue;
                        }
                        // URLs with absolute paths like /w/index.php need to be expanded
                        // to absolute URLs but otherwise left alone
                        if ( $match['file'][0] !== '' && $match['file'][0][0] === '/' ) {
                                // Replace the file path with an expanded (possibly protocol-relative) URL
                                // ...but only if wfExpandUrl() is even available.
                                // This will not be the case if we're running outside of MW
                                $lengthIncrease = 0;
                                if ( function_exists( 'wfExpandUrl' ) ) {
                                        $expanded = wfExpandUrl( $match['file'][0], PROTO_RELATIVE );
                                        $origLength = strlen( $match['file'][0] );
                                        $lengthIncrease = strlen( $expanded ) - $origLength;
                                        $source = substr_replace( $source, $expanded,
                                                $match['file'][1], $origLength
                                        );
                                }
                                // Move the offset to the end of the match, leaving it alone
                                $offset = $match[0][1] + strlen( $match[0][0] ) + $lengthIncrease;
                                continue;
                        }

                        // Guard against double slashes, because "some/remote/../foo.png"
                        // resolves to "some/remote/foo.png" on (some?) clients (bug 27052).
                        if ( substr( $remote, -1 ) == '/' ) {
                                $remote = substr( $remote, 0, -1 );
                        }

                        // Shortcuts
                        $embed = $match['embed'][0];
                        $pre = $match['pre'][0];
                        $post = $match['post'][0];
                        $query = $match['query'][0];
                        $url = "{$remote}/{$match['file'][0]}";
                        $file = "{$local}/{$match['file'][0]}";

                        $replacement = false;

                        if ( $local !== false && file_exists( $file ) ) {
                                // Add version parameter as a time-stamp in ISO 8601 format,
                                // using Z for the timezone, meaning GMT
                                $url .= '?' . gmdate( 'Y-m-d\TH:i:s\Z', round( filemtime( $file ), -2 ) );
                                // Embedding requires a bit of extra processing, so let's skip that if we can
                                if ( $embedData && $embed ) {
                                        $type = self::getMimeType( $file );
                                        // Detect when URLs were preceeded with embed tags, and also verify file size is
                                        // below the limit
                                        if (
                                                $type
                                                && $match['embed'][1] > 0
                                                && filesize( $file ) < self::EMBED_SIZE_LIMIT
                                        ) {
                                                // Strip off any trailing = symbols (makes browsers freak out)
                                                $data = base64_encode( file_get_contents( $file ) );
                                                // Build 2 CSS properties; one which uses a base64 encoded data URI in place
                                                // of the @embed comment to try and retain line-number integrity, and the
                                                // other with a remapped an versioned URL and an Internet Explorer hack
                                                // making it ignored in all browsers that support data URIs
                                                $replacement = "{$pre}url(data:{$type};base64,{$data}){$post};";
                                                $replacement .= "{$pre}url({$url}){$post}!ie;";
                                        }
                                }
                                if ( $replacement === false ) {
                                        // Assume that all paths are relative to $remote, and make them absolute
                                        $replacement = "{$embed}{$pre}url({$url}){$post};";
                                }
                        } elseif ( $local === false ) {
                                // Assume that all paths are relative to $remote, and make them absolute
                                $replacement = "{$embed}{$pre}url({$url}{$query}){$post};";
                        }
                        if ( $replacement !== false ) {
                                // Perform replacement on the source
                                $source = substr_replace(
                                        $source, $replacement, $match[0][1], strlen( $match[0][0] )
                                );
                                // Move the offset to the end of the replacement in the source
                                $offset = $match[0][1] + strlen( $replacement );
                                continue;
                        }
                        // Move the offset to the end of the match, leaving it alone
                        $offset = $match[0][1] + strlen( $match[0][0] );
                }
                return $source;
        }

        /**
         * Removes whitespace from CSS data
         *
         * @param string $css CSS data to minify
         * @return string Minified CSS data
         */
        public static function minify( $css ) {
                return trim(
                        str_replace(
                                array( '; ', ': ', ' {', '{ ', ', ', '} ', ';}' ),
                                array( ';', ':', '{', '{', ',', '}', '}' ),
                                preg_replace( array( '/\s+/', '/\/\*.*?\*\//s' ), array( ' ', '' ), $css )
                        )
                );
        }
}