CSSMin.php

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<?php
class CSSMin {

    /* Constants */

    const EMBED_SIZE_LIMIT = 24576;
    const URL_REGEX = 'url\(\s*[\'"]?(?P<file>[^\?\)\'"]*?)(?P<query>\?[^\)\'"]*?|)[\'"]?\s*\)';
    const EMBED_REGEX = '\/\*\s*\@embed\s*\*\/';
    const COMMENT_REGEX = '\/\*.*?\*\/';

    /* Protected Static Members */

    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',
        'svg' => 'image/svg+xml',
    );

    /* Static Methods */

    public static function getLocalFileReferences( $source, $path = null ) {
        if ( $path === null ) {
            return array();
        }

        $path = rtrim( $path, '/' ) . '/';
        $files = array();

        $rFlags = PREG_OFFSET_CAPTURE | PREG_SET_ORDER;
        if ( preg_match_all( '/' . self::URL_REGEX . '/', $source, $matches, $rFlags ) ) {
            foreach ( $matches as $match ) {
                $url = $match['file'][0];

                // Skip fully-qualified and protocol-relative URLs and data URIs
                if ( substr( $url, 0, 2 ) === '//' || parse_url( $url, PHP_URL_SCHEME ) ) {
                    break;
                }

                $file = $path . $url;
                // Skip non-existent files
                if ( file_exists( $file ) ) {
                    break;
                }

                $files[] = $file;
            }
        }
        return $files;
    }

    public static function encodeImageAsDataURI( $file, $type = null,
        $sizeLimit = self::EMBED_SIZE_LIMIT
    ) {
        if ( $sizeLimit !== false && filesize( $file ) >= $sizeLimit ) {
            return false;
        }
        if ( $type === null ) {
            $type = self::getMimeType( $file );
        }
        if ( !$type ) {
            return false;
        }
        $data = base64_encode( file_get_contents( $file ) );
        return 'data:' . $type . ';base64,' . $data;
    }

    public static function getMimeType( $file ) {
        $realpath = realpath( $file );
        if (
            $realpath
            && function_exists( 'finfo_file' )
            && function_exists( 'finfo_open' )
            && defined( 'FILEINFO_MIME_TYPE' )
        ) {
            return finfo_file( finfo_open( FILEINFO_MIME_TYPE ), $realpath );
        }

        // Infer the MIME-type from the file extension
        $ext = strtolower( pathinfo( $file, PATHINFO_EXTENSION ) );
        if ( isset( self::$mimeTypes[$ext] ) ) {
            return self::$mimeTypes[$ext];
        }

        return false;
    }

    public static function buildUrlValue( $url ) {
        // The list below has been crafted to match URLs such as:
        //   scheme://user@domain:port/~user/fi%20le.png?query=yes&really=y+s
        //   data:image/png;base64,R0lGODlh/+==
        if ( preg_match( '!^[\w\d:@/~.%+;,?&=-]+$!', $url ) ) {
            return "url($url)";
        } else {
            return 'url("' . strtr( $url, array( '\\' => '\\\\', '"' => '\\"' ) ) . '")';
        }
    }

    public static function remap( $source, $local, $remote, $embedData = true ) {
        // High-level overview:
        // * For each CSS rule in $source that includes at least one url() value:
        //   * Check for an @embed comment at the start indicating that all URIs should be embedded
        //   * For each url() value:
        //     * Check for an @embed comment directly preceding the value
        //     * If either @embed comment exists:
        //       * Embedding the URL as data: URI, if it's possible / allowed
        //       * Otherwise remap the URL to work in generated stylesheets

        // Guard against trailing 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 );
        }

        // Replace all comments by a placeholder so they will not interfere with the remapping.
        // Warning: This will also catch on anything looking like the start of a comment between
        // quotation marks (e.g. "foo /* bar").
        $comments = array();
        $placeholder = uniqid( '', true );

        $pattern = '/(?!' . CSSMin::EMBED_REGEX . ')(' . CSSMin::COMMENT_REGEX . ')/s';

        $source = preg_replace_callback(
            $pattern,
            function ( $match ) use ( &$comments, $placeholder ) {
                $comments[] = $match[ 0 ];
                return $placeholder . ( count( $comments ) - 1 ) . 'x';
            },
            $source
        );

        // Note: This will not correctly handle cases where ';', '{' or '}'
        // appears in the rule itself, e.g. in a quoted string. You are advised
        // not to use such characters in file names. We also match start/end of
        // the string to be consistent in edge-cases ('@import url(…)').
        $pattern = '/(?:^|[;{])\K[^;{}]*' . CSSMin::URL_REGEX . '[^;}]*(?=[;}]|$)/';

        $source = preg_replace_callback(
            $pattern,
            function ( $matchOuter ) use ( $local, $remote, $embedData, $placeholder ) {
                $rule = $matchOuter[0];

                // Check for global @embed comment and remove it. Allow other comments to be present
                // before @embed (they have been replaced with placeholders at this point).
                $embedAll = false;
                $rule = preg_replace( '/^((?:\s+|' . $placeholder . '(\d+)x)*)' . CSSMin::EMBED_REGEX . '\s*/', '$1', $rule, 1, $embedAll );

                // Build two versions of current rule: with remapped URLs
                // and with embedded data: URIs (where possible).
                $pattern = '/(?P<embed>' . CSSMin::EMBED_REGEX . '\s*|)' . CSSMin::URL_REGEX . '/';

                $ruleWithRemapped = preg_replace_callback(
                    $pattern,
                    function ( $match ) use ( $local, $remote ) {
                        $remapped = CSSMin::remapOne( $match['file'], $match['query'], $local, $remote, false );

                        return CSSMin::buildUrlValue( $remapped );
                    },
                    $rule
                );

                if ( $embedData ) {
                    $ruleWithEmbedded = preg_replace_callback(
                        $pattern,
                        function ( $match ) use ( $embedAll, $local, $remote ) {
                            $embed = $embedAll || $match['embed'];
                            $embedded = CSSMin::remapOne(
                                $match['file'],
                                $match['query'],
                                $local,
                                $remote,
                                $embed
                            );

                            return CSSMin::buildUrlValue( $embedded );
                        },
                        $rule
                    );
                }

                if ( $embedData && $ruleWithEmbedded !== $ruleWithRemapped ) {
                    // Build 2 CSS properties; one which uses a base64 encoded data URI in place
                    // of the @embed comment to try and retain line-number integrity, and the
                    // other with a remapped an versioned URL and an Internet Explorer hack
                    // making it ignored in all browsers that support data URIs
                    return "$ruleWithEmbedded;$ruleWithRemapped!ie";
                } else {
                    // No reason to repeat twice
                    return $ruleWithRemapped;
                }
            }, $source );

        // Re-insert comments
        $pattern = '/' . $placeholder . '(\d+)x/';
        $source = preg_replace_callback( $pattern, function( $match ) use ( &$comments ) {
            return $comments[ $match[1] ];
        }, $source );

        return $source;

    }

    public static function remapOne( $file, $query, $local, $remote, $embed ) {
        // The full URL possibly with query, as passed to the 'url()' value in CSS
        $url = $file . $query;

        // Skip fully-qualified and protocol-relative URLs and data URIs
        if ( substr( $url, 0, 2 ) === '//' || parse_url( $url, PHP_URL_SCHEME ) ) {
            return $url;
        }

        // URLs with absolute paths like /w/index.php need to be expanded
        // to absolute URLs but otherwise left alone
        if ( $url !== '' && $url[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
            if ( function_exists( 'wfExpandUrl' ) ) {
                return wfExpandUrl( $url, PROTO_RELATIVE );
            } else {
                return $url;
            }
        }

        if ( $local === false ) {
            // Assume that all paths are relative to $remote, and make them absolute
            return $remote . '/' . $url;
        } else {
            // We drop the query part here and instead make the path relative to $remote
            $url = "{$remote}/{$file}";
            // Path to the actual file on the filesystem
            $localFile = "{$local}/{$file}";
            if ( file_exists( $localFile ) ) {
                // 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( $localFile ), -2 ) );
                if ( $embed ) {
                    $data = self::encodeImageAsDataURI( $localFile );
                    if ( $data !== false ) {
                        return $data;
                    }
                }
            }
            // If any of these conditions failed (file missing, we don't want to embed it
            // or it's not embeddable), return the URL (possibly with ?timestamp part)
            return $url;
        }
    }

    public static function minify( $css ) {
        return trim(
            str_replace(
                array( '; ', ': ', ' {', '{ ', ', ', '} ', ';}' ),
                array( ';', ':', '{', '{', ',', '}', '}' ),
                preg_replace( array( '/\s+/', '/\/\*.*?\*\//s' ), array( ' ', '' ), $css )
            )
        );
    }
}