text: /**
   * @author: @AngularClass
   */
  const helpers = require('./helpers');
  const buildUtils = require('./build-utils');
  
  /**
   * Used to merge webpack configs
  */
  const webpackMerge = require('webpack-merge');
  /**
   * The settings that are common to prod and dev
  */
  const commonConfig = require('./webpack.common.js');
  
  /**
   * Webpack Plugins
   */
  const SourceMapDevToolPlugin = require('webpack/lib/SourceMapDevToolPlugin');
  const ExtractTextPlugin = require('extract-text-webpack-plugin');
  const HashedModuleIdsPlugin = require('webpack/lib/HashedModuleIdsPlugin')
  const PurifyPlugin = require('@angular-devkit/build-optimizer').PurifyPlugin;
  const ModuleConcatenationPlugin = require('webpack/lib/optimize/ModuleConcatenationPlugin');
  const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
  
  function getUglifyOptions (supportES2015) {
    const uglifyCompressOptions = {
      pure_getters: true, /* buildOptimizer */
      // PURE comments work best with 3 passes.
      // See https://github.com/webpack/webpack/issues/2899#issuecomment-317425926.
      passes: 3         /* buildOptimizer */
    };
  
    return {
      ecma: supportES2015 ? 6 : 5,
      warnings: false,    // TODO verbose based on option?
      ie8: false,
      mangle: true,
      compress: uglifyCompressOptions,
      output: {
        ascii_only: true,
        comments: false
      }
    };
  }
  
  module.exports = function (env) {
    const ENV = process.env.NODE_ENV = process.env.ENV = 'production';
    const supportES2015 = buildUtils.supportES2015(buildUtils.DEFAULT_METADATA.tsConfigPath);
    const METADATA = Object.assign({}, buildUtils.DEFAULT_METADATA, {
      merchant: env.merchant,
      baseUrl: '/' + env.merchant,
      title: env.displayname,
      host: process.env.HOST || 'localhost',
      port: process.env.PORT || 8080,
      ENV: ENV,
      HMR: false
    });
  
    // set environment suffix so these environments are loaded.
    METADATA.envFileSuffix = METADATA.E2E ? 'e2e.prod' : 'prod';
  
    return webpackMerge(commonConfig({ env: ENV, metadata: METADATA }), {
  
      /**
       * Options affecting the output of the compilation.
       *
       * See: http://webpack.github.io/docs/configuration.html#output
       */
      output: {
  
        /**
         * The output directory as absolute path (required).
         *
         * See: http://webpack.github.io/docs/configuration.html#output-path
         */
        path: helpers.root('dist'),
  
        /**
         * Specifies the name of each output file on disk.
         * IMPORTANT: You must not specify an absolute path here!
         *
         * See: http://webpack.github.io/docs/configuration.html#output-filename
         */
        filename: '[name].[chunkhash].bundle.js',
  
        /**
         * The filename of the SourceMaps for the JavaScript files.
         * They are inside the output.path directory.
         *
         * See: http://webpack.github.io/docs/configuration.html#output-sourcemapfilename
         */
        sourceMapFilename: '[file].map',
  
        /**
         * The filename of non-entry chunks as relative path
         * inside the output.path directory.
         *
         * See: http://webpack.github.io/docs/configuration.html#output-chunkfilename
         */
        chunkFilename: '[name].[chunkhash].chunk.js'
  
      },
  
      module: {
  
        rules: [
  
          /**
           * Extract CSS files from .src/styles directory to external CSS file
           */
          {
            test: /\.css$/,
            loader: ExtractTextPlugin.extract({
              fallback: 'style-loader',
              use: 'css-loader'
            }),
            include: [helpers.root('src', 'styles')]
          },
  
          /**
           * Extract and compile SCSS files from .src/styles directory to external CSS file
           */
          {
            test: /\.scss$/,
            loader: ExtractTextPlugin.extract({
              fallback: 'style-loader',
              use: 'css-loader!sass-loader'
            }),
            include: [helpers.root('src', 'styles')]
          },
  
        ]
  
      },
  
      /**
       * Add additional plugins to the compiler.
       *
       * See: http://webpack.github.io/docs/configuration.html#plugins
       */
      plugins: [
  
        // new SourceMapDevToolPlugin({
        //   filename: '[file].map[query]',
        //   moduleFilenameTemplate: '[resource-path]',
        //   fallbackModuleFilenameTemplate: '[resource-path]?[hash]',
        //   sourceRoot: 'webpack:///'
        // }),
  
  
        /**
         * Plugin: ExtractTextPlugin
         * Description: Extracts imported CSS files into external stylesheet
         *
         * See: https://github.com/webpack/extract-text-webpack-plugin
         */
        new ExtractTextPlugin('[name].[contenthash].css'),
  
        new PurifyPlugin(), /* buildOptimizer */
  
        new HashedModuleIdsPlugin(),
        new ModuleConcatenationPlugin(),
  
        /**
         * Plugin: UglifyJsPlugin
         * Description: Minimize all JavaScript output of chunks.
         * Loaders are switched into minimizing mode.
         *
         * See: https://webpack.github.io/docs/list-of-plugins.html#uglifyjsplugin
         *
         * NOTE: To debug prod builds uncomment //debug lines and comment //prod lines
         */
        new UglifyJsPlugin({
          sourceMap: false,
          uglifyOptions: getUglifyOptions(supportES2015)
        })
  
      ],
  
      /**
       * Include polyfills or mocks for various node stuff
       * Description: Node configuration
       *
       * See: https://webpack.github.io/docs/configuration.html#node
       */
      node: {
        global: true,
        crypto: 'empty',
        process: false,
        module: false,
        clearImmediate: false,
        setImmediate: false
      }
  
    });
  }
  