feat(build): broccoli less plugin

Author: jkuri

lib/broccoli/broccoli-less.js

@@ -0,0 +1,67 @@
+/* jshint node: true, esversion: 6 */
+'use strict';
+
+try {
+  process.env.NODE_PATH += `:${process.env.PWD}/node_modules`;
+  require('module').Module._initPaths();
+  require.resolve('less');
+
+  const Plugin  = require('broccoli-caching-writer');
+  const fs      = require('fs');
+  const fse     = require('fs-extra');
+  const path    = require('path');
+  const less    = require('less');
+
+  class LESSPlugin extends Plugin {
+    constructor(inputNodes, options) {
+      super(inputNodes, {});
+
+      options = options || {};
+      Plugin.call(this, inputNodes, {
+        cacheInclude: [/(.*?).less$/]
+      });
+      this.options = options;
+      this.fileRegistry = [];
+    }
+
+    build() {
+      const that = this;
+      let entries = this.listEntries();
+      let rootFileNames = entries.map(e => {
+        return path.resolve(e.basePath, e.relativePath);
+      });
+
+      let promises = [];
+
+      rootFileNames.forEach(fileName => {
+        let p = new Promise(resolve => {
+          that.compile(fileName, that.inputPaths[0], that.outputPath)
+            .then(() => {
+              resolve();  
+            });
+        });
+
+        promises.push(p);
+      });
+
+      return Promise.all(promises);
+    }
+
+    compile(fileName, inputPath, outputPath) {
+      return new Promise(resolve => {
+        let content = fs.readFileSync(fileName, 'utf8');
+
+        less.render(content)
+        .then(output => {
+          let filePath = fileName.replace(inputPath, outputPath).replace(/\.less$/, '.css');
+          fse.outputFileSync(filePath, output.css, 'utf8');
+          resolve();
+        });
+      });
+    }
+  }
+
+  module.exports = LESSPlugin;
+} catch (e) { 
+  module.exports = null;
+}