[INTERNAL] introduce clean css

WIP

Author: tobiasso85

lib/processors/cssOptimizer.js

@@ -0,0 +1,35 @@
+const CleanCSS = require("clean-css");
+const log = require("@ui5/logger").getLogger("builder:processors:cssOptimizer");
+
+/**
+ * Optimizes the supplied resources.
+ *
+ * @public
+ * @alias module:@ui5/builder.processors.cssOptimizer
+ * @param {Object} parameters Parameters
+ * @param {module:@ui5/fs.Resource[]} parameters.resources List of resources to be processed
+ * @returns {Promise<module:@ui5/fs.Resource[]>} Promise resolving with optimized resources
+ */
+module.exports = function({resources}) {
+	return Promise.all(resources.map((resource) => {
+		return resource.getString().then((css) => {
+			const options = {
+				compatibility: {
+					properties: {
+						colors: false
+					}
+				},
+				returnPromise: true
+			};
+			return new CleanCSS(options).minify(css).then((result) => {
+				if (Array.isArray(result.warnings) && result.warnings.length > 0) {
+					log.warn(`Warnings occurred: ${result.warnings.join(", ")}`);
+				}
+				resource.setString(result.styles);
+				return resource;
+			}, (error) => {
+				throw new Error(`Errors occurred: ${error.join(", ")}`);
+			});
+		});
+	}));
+};

lib/tasks/buildThemes.js

@@ -1,4 +1,5 @@
 const themeBuilder = require("../processors/themeBuilder");
+const cssOptimizer = require("../processors/cssOptimizer");
 const ReaderCollectionPrioritized = require("@ui5/fs").ReaderCollectionPrioritized;
 const fsInterface = require("@ui5/fs").fsInterface;
 
@@ -17,7 +18,7 @@ const fsInterface = require("@ui5/fs").fsInterface;
  * @param {boolean} [parameters.options.compress=true]
  * @returns {Promise<undefined>} Promise resolving with <code>undefined</code> once data has been written
  */
-module.exports = function({workspace, dependencies, options}) {
+module.exports = async function({workspace, dependencies, options}) {
 	const combo = new ReaderCollectionPrioritized({
 		name: `theme - prioritize workspace over dependencies: ${options.projectName}`,
 		readers: [workspace, dependencies]
@@ -30,13 +31,13 @@ module.exports = function({workspace, dependencies, options}) {
 		promises.push(combo.byGlob(options.librariesPattern));
 	}
 
-	const compress = options.compress === undefined ? true : options.compress;
+	const [allResources, availableLibraries] = await Promise.all(promises);
 
-	return Promise.all(promises).then(([allResources, availableLibraries]) => {
-		if (!availableLibraries || availableLibraries.length === 0) {
-			// Try to build all themes
-			return allResources;
-		}
+	let resources;
+	if (!availableLibraries || availableLibraries.length === 0) {
+		// Try to build all themes
+		resources = allResources;
+	} else {
 		/* Don't try to build themes for libraries that are not available
 			(maybe replace this with something more aware of which dependencies are optional and therefore
 			legitimately missing and which not (fault case))
@@ -54,18 +55,22 @@ module.exports = function({workspace, dependencies, options}) {
 			return false;
 		};
 
-		return allResources.filter(isAvailable);
-	}).then((resources) => {
-		return themeBuilder({
-			resources,
-			fs: fsInterface(combo),
-			options: {
-				compress
-			}
-		});
-	}).then((processedResources) => {
-		return Promise.all(processedResources.map((resource) => {
-			return workspace.write(resource);
-		}));
+		resources = await allResources.filter(isAvailable);
+	}
+	const processedResources = await themeBuilder({
+		resources,
+		fs: fsInterface(combo)
 	});
+
+	const compress = options.compress === undefined ? true : options.compress;
+	if (compress) {
+		const cssResources = processedResources.filter((resource) => {
+			return resource.getPath().endsWith(".css");
+		});
+		await cssOptimizer({resources: cssResources,
+			fs: fsInterface(combo)});
+	}
+	return Promise.all(processedResources.map((resource) => {
+		return workspace.write(resource);
+	}));
 };

package-lock.json

@@ -100,6 +100,7 @@
 		"@ui5/fs": "^1.1.2",
 		"@ui5/logger": "^1.0.2",
 		"cheerio": "^0.22.0",
+		"clean-css": "^4.2.1",
 		"escape-unicode": "^0.2.0",
 		"escodegen": "^1.12.1",
 		"escope": "^3.6.0",