Add options (and some flexibility) to the plugin

Add info to README

Author: NMFR

README.md

@@ -1,3 +1,45 @@
 # Optimize CSS Assets Webpack Plugin
 
 A Webpack plugin to optimize \ minimize CSS assets.
+
+## What does the plugin do?
+
+It will search for CSS assets during the Webpack build and will optimize \ minimize the CSS (by default it uses [cssnano](http://github.com/ben-eb/cssnano) but a custom css processor can be specified). 
+
+### Solves [extract-text-webpack-plugin](http://github.com/webpack/extract-text-webpack-plugin) CSS duplication problem:
+
+Since [extract-text-webpack-plugin](http://github.com/webpack/extract-text-webpack-plugin) only bundles (merges) text chunks, if its used to bundle CSS, the bundle might have duplicate entries (chunks can be duplicate free but when merged, duplicate CSS can be created).
+
+## Configuration:
+
+The plugin can receive the following options (all of them are optional):
+* assetNameRegExp: A regular expression that indicates the names of the assets that should be optimized \ minimized, defaults to `/\.css$/g` 
+* cssProcessor: The css processor used to optimize \ minimize the CSS, defaults to [cssnano](http://github.com/ben-eb/cssnano). This should be a function that follows cssnano.process interface (receives a css and options parameters and returns a Promise). 
+* cssProcessorOptions: The options passed to the cssProcessor, defaults to `{}`  
+* canPrint: A boolean indicating if the plugin can print messages to the console, defaults to `true`
+
+## Example:
+
+``` javascript
+var OptimizeCssAssetsPlugin = require('optimize-css-assets-webpack-plugin');
+module.exports = {
+	module: {
+		loaders: [
+			{ test: /\.css$/, loader: ExtractTextPlugin.extract("style-loader", "css-loader") }
+		]
+	},
+	plugins: [
+		new ExtractTextPlugin("styles.css"),
+    new OptimizeCssAssetsPlugin({
+      assetNameRegExp: /\.optimize\.css$/g,
+      cssProcessor: require('cssnano'),
+      cssProcessorOptions: { discardComments: {removeAll: true } },
+      canPrint: true
+    })
+	]
+}
+```
+
+## License
+
+MIT (http://www.opensource.org/licenses/mit-license.php)

index.js

@@ -1,51 +1,104 @@
 var _ = require('underscore');
-var cssnano = require('cssnano');
 
-function OptimizeCssAssetsPlugin() {};
+function OptimizeCssAssetsPlugin(options) {
+  this.options = options || {};
+  
+  if (this.options.assetNameRegExp === undefined) {
+    this.options.assetNameRegExp = /\.css$/g;
+  }
+  
+  if (this.options.cssProcessor === undefined) {
+    this.options.cssProcessor = require('cssnano');
+  }
+  
+  if (this.options.cssProcessorOptions === undefined) {
+    this.options.cssProcessorOptions = {};
+  }
+  
+  if (this.options.canPrint === undefined) {
+    this.options.canPrint = true;
+  }
+};
+
+OptimizeCssAssetsPlugin.prototype.print = function() {
+  if (this.options.canPrint) {
+    console.log.apply(console, arguments);  
+  }
+};
+
+OptimizeCssAssetsPlugin.prototype.processCss = function(css) {
+  return this.options.cssProcessor.process(css, this.options.cssProcessorOptions); 
+};
+
+OptimizeCssAssetsPlugin.prototype.createCssAsset = function(css, originalAsset) {
+  return {
+    source: function() {
+      return css;
+    },
+    size: function() {
+      return css.length;
+    }
+  };
+};
 
 OptimizeCssAssetsPlugin.prototype.apply = function(compiler) {
+  
+  var self = this;
+  
   compiler.plugin('emit', function(compilation, compileCallback) {
 
-    console.log('');
-    console.log('Starting to optimize CSS...');
+    self.print('\nStarting to optimize CSS...');
 
-    var cssFiles = _.filter(_.keys(compilation.assets), function(fn){ return fn && fn.match && fn.match(/\.css$/g); });
+    var assets = compilation.assets;
 
-    var counter = 0;
-    function checkFinish() {
-      if (cssFiles.length >= counter++) {
-        console.log('CSS optimize ended.');
-        compileCallback();
+    var cssAssetNames = _.filter(
+      _.keys(assets), 
+      function(assetName) { 
+        return assetName.match(self.options.assetNameRegExp);
       }
-    };
+    );
+    
+    var hasErrors = false;
+    var promises = [];
 
     _.each(
-      cssFiles,
+      cssAssetNames,
       function(assetName) {
-        console.log('Processing ' + assetName);
-        var asset = compilation.assets[assetName];
+        
+        self.print('Processing ' + assetName + '...');
+        
+        var asset = assets[assetName];
+        
         var originalCss = asset.source();
-        cssnano.process(originalCss, {discardComments: {removeAll: true}}).then(
+        
+        var promise = self.processCss(originalCss); 
+        
+        promise.then(
           function (result) {
+            
+            if (hasErrors) {
+              self.print('Skiping ' + assetName + ' because of an error.');  
+              return;
+            }
+            
             var processedCss = result.css;
-            compilation.assets[assetName] = {
-              source: function() {
-                return processedCss;
-              },
-              size: function() {
-                return processedCss.length;
-              }
-            };
-            console.log('Processing ' + assetName + ' ended, before: ' + originalCss.length + ', after: ' + processedCss.length + ', ratio: ' + (Math.round(((processedCss.length * 100) / originalCss.length) * 100) / 100) + '%');
-            checkFinish();
+            
+            assets[assetName] = self.createCssAsset(processedCss, asset);
+            
+            self.print('Processed ' + assetName + ', before: ' + originalCss.length + ', after: ' + processedCss.length + ', ratio: ' + (Math.round(((processedCss.length * 100) / originalCss.length) * 100) / 100) + '%');
+            
           }, function(err) {
-            console.log('Error processing file: ' + assetName);
-            console.log(err);
-            checkFinish();
+            hasErrors = true;
+            self.print('Error processing file: ' + assetName);
+            console.error(err);
           }
         );
+        
+        promises.push(promise);
       }
     );
+    
+    Promise.all(promises).then(function () { compileCallback(); }, compileCallback);
   });
 };
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "optimize-css-assets-webpack-plugin",
-  "version": "1.1.0",
+  "version": "1.2.0",
   "author": "Nuno Rodrigues",
   "description": "A Webpack plugin to optimize \\ minimize CSS assets.",
   "dependencies": {