Support LESS stylesheets in ResourceLoader

[lhc/web/wiklou.git] / includes / resourceloader / ResourceLoaderFileModule.php

diff --git a/includes/resourceloader/ResourceLoaderFileModule.php b/includes/resourceloader/ResourceLoaderFileModule.php
index 10c25f0..ead81cc 100644 (file)
--- a/includes/resourceloader/ResourceLoaderFileModule.php
+++ b/includes/resourceloader/ResourceLoaderFileModule.php
@@ -115,6 +115,12 @@ class ResourceLoaderFileModule extends ResourceLoaderModule {
        protected $raw = false;
        protected $targets = array( 'desktop' );
 
+       /**
+        * Boolean: Whether getStyleURLsForDebug should return raw file paths,
+        * or return load.php urls
+        */
+       protected $hasGeneratedStyles = false;
+
        /**
         * Array: Cache for mtime
         * @par Usage:
@@ -334,6 +340,13 @@ class ResourceLoaderFileModule extends ResourceLoaderModule {
         * @return array
         */
        public function getStyleURLsForDebug( ResourceLoaderContext $context ) {
+               if ( $this->hasGeneratedStyles ) {
+                       // Do the default behaviour of returning a url back to load.php
+                       // but with only=styles.
+                       return parent::getStyleURLsForDebug( $context );
+               }
+               // Our module consists entirely of real css files,
+               // in debug mode we can load those directly.
                $urls = array();
                foreach ( $this->getStyleFiles( $context ) as $mediaType => $list ) {
                        $urls[$mediaType] = array();
@@ -470,6 +483,16 @@ class ResourceLoaderFileModule extends ResourceLoaderModule {
                return "{$this->remoteBasePath}/$path";
        }
 
+       /**
+        * Infer the stylesheet language from a stylesheet file path.
+        *
+        * @param string $path
+        * @return string: the stylesheet language name
+        */
+       protected function getStyleSheetLang( $path ) {
+               return preg_match( '/\.less$/i', $path ) ? 'less' : 'css';
+       }
+
        /**
         * Collates file paths by option (where provided).
         *
@@ -632,7 +655,14 @@ class ResourceLoaderFileModule extends ResourceLoaderModule {
                        wfDebugLog( 'resourceloader', $msg );
                        throw new MWException( $msg );
                }
-               $style = file_get_contents( $localPath );
+
+               if ( $this->getStyleSheetLang( $path ) === 'less' ) {
+                       $style = $this->compileLESSFile( $localPath );
+                       $this->hasGeneratedStyles = true;
+               } else {
+                       $style = file_get_contents( $localPath );
+               }
+
                if ( $flip ) {
                        $style = CSSJanus::transform( $style, true, false );
                }
@@ -671,4 +701,82 @@ class ResourceLoaderFileModule extends ResourceLoaderModule {
                return $this->targets;
        }
 
+       /**
+        * Generate a cache key for a LESS file.
+        * The cache key varies on the file name, the names and values of global
+        * LESS variables, and the value of $wgShowExceptionDetails. Varying on
+        * $wgShowExceptionDetails ensures the CSS comment indicating compilation
+        * failure shows the right level of detail.
+        *
+        * @param string $fileName File name of root LESS file.
+        * @return string: Cache key
+        */
+       protected static function getLESSCacheKey( $fileName ) {
+               global $wgShowExceptionDetails;
+
+               $vars = json_encode( self::getLESSVars() );
+               $hash = md5( $fileName . $vars );
+               return wfMemcKey( 'resourceloader', 'less', (string)$wgShowExceptionDetails, $hash );
+       }
+
+       /**
+        * Compile a LESS file into CSS.
+        *
+        * If invalid, returns replacement CSS source consisting of the compilation
+        * error message encoded as a comment. To save work, we cache a result object
+        * which comprises the compiled CSS and the names & mtimes of the files
+        * that were processed. lessphp compares the cached & current mtimes and
+        * recompiles as necessary.
+        *
+        * @param string $fileName File path of LESS source
+        * @return string: CSS source
+        */
+       protected function compileLESSFile( $fileName ) {
+               global $wgShowExceptionDetails;
+
+               $key = self::getLESSCacheKey( $fileName );
+               $cache = wfGetCache( CACHE_ANYTHING );
+
+               // The input to lessc. Either an associative array representing the
+               // cached results of a previous compilation, or the string file name if
+               // no cache result exists.
+               $source = $cache->get( $key );
+               if ( !is_array( $source ) || !isset( $source['root'] ) ) {
+                       $source = $fileName;
+               }
+
+               $compiler = self::lessCompiler();
+               $expire = 0;
+               try {
+                       $result = $compiler->cachedCompile( $source );
+                       if ( !is_array( $result ) ) {
+                               throw new Exception( 'LESS compiler result has type ' . gettype( $result ) . '; array expected.' );
+                       }
+               } catch ( Exception $e ) {
+                       // The exception might have been caused by an imported file rather
+                       // than the root node. But we don't know which files were imported,
+                       // because compilation failed; we thus cannot rely on file mtime to
+                       // know when to reattempt compilation. Expire in 5 mins. instead.
+                       $expire = 300;
+                       wfDebugLog( 'resourceloader', __METHOD__ . ": $e" );
+                       $result = array();
+                       $result['root'] = $fileName;
+
+                       if ( $wgShowExceptionDetails ) {
+                               $result['compiled'] = ResourceLoader::makeComment( 'LESS error: ' . $e->getMessage() );
+                       } else {
+                               $result['compiled'] = ResourceLoader::makeComment( 'LESS stylesheet compilation failed. ' .
+                                       'Set "$wgShowExceptionDetails = true;" to show detailed debugging information.' );
+                       }
+
+                       $result['files'] = array( $fileName => self::safeFilemtime( $fileName ) );
+                       $result['updated'] = time();
+               }
+               // Tie cache expiry to the names and mtimes of image files that were
+               // embedded in the generated CSS source.
+               $result['files'] += $compiler->embeddedImages;
+               $this->localFileRefs += array_keys( $result['files'] );
+               $cache->set( $key, $result, $expire );
+               return $result['compiled'];
+       }
 }