text: 'use strict';
  
  const autoprefixer = require('autoprefixer');
  const path = require('path');
  const webpack = require('webpack');
  const HtmlWebpackPlugin = require('html-webpack-plugin');
  const ExtractTextPlugin = require('extract-text-webpack-plugin');
  const ManifestPlugin = require('webpack-manifest-plugin');
  const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
  const SWPrecacheWebpackPlugin = require('sw-precache-webpack-plugin');
  const eslintFormatter = require('react-dev-utils/eslintFormatter');
  const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
  const paths = require('./paths');
  const getClientEnvironment = require('./env');
  
  // Webpack uses `publicPath` to determine where the app is being served from.
  // It requires a trailing slash, or the file assets will get an incorrect path.
  const publicPath = paths.servedPath;
  // Some apps do not use client-side routing with pushState.
  // For these, "homepage" can be set to "." to enable relative asset paths.
  const shouldUseRelativeAssetPaths = publicPath === './';
  // Source maps are resource heavy and can cause out of memory issue for large source files.
  const shouldUseSourceMap = process.env.GENERATE_SOURCEMAP !== 'false';
  // `publicUrl` is just like `publicPath`, but we will provide it to our app
  // as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.
  // Omit trailing slash as %PUBLIC_URL%/xyz looks better than %PUBLIC_URL%xyz.
  const publicUrl = publicPath.slice(0, -1);
  // Get environment variables to inject into our app.
  const env = getClientEnvironment(publicUrl);
  
  // Assert this just to be safe.
  // Development builds of React are slow and not intended for production.
  if (env.stringified['process.env'].NODE_ENV !== '"production"') {
    throw new Error('Production builds must have NODE_ENV=production.');
  }
  
  // Note: defined here because it will be used more than once.
  const cssFilename = 'static/css/[name].[contenthash:8].css';
  
  // ExtractTextPlugin expects the build output to be flat.
  // (See https://github.com/webpack-contrib/extract-text-webpack-plugin/issues/27)
  // However, our output is structured with css, js and media folders.
  // To have this structure working with relative paths, we have to use custom options.
  const extractTextPluginOptions = shouldUseRelativeAssetPaths
    ? // Making sure that the publicPath goes back to to build folder.
      { publicPath: Array(cssFilename.split('/').length).join('../') }
    : {};
  
  // This is the production configuration.
  // It compiles slowly and is focused on producing a fast and minimal bundle.
  // The development configuration is different and lives in a separate file.
  module.exports = {
    // Don't attempt to continue if there are any errors.
    bail: true,
    // We generate sourcemaps in production. This is slow but gives good results.
    // You can exclude the *.map files from the build during deployment.
    devtool: shouldUseSourceMap ? 'source-map' : false,
    // In production, we only want to load the polyfills and the app code.
    entry: [require.resolve('./polyfills'), paths.appIndexJs],
    output: {
      // The build folder.
      path: paths.appBuild,
      // Generated JS file names (with nested folders).
      // There will be one main bundle, and one file per asynchronous chunk.
      // We don't currently advertise code splitting but Webpack supports it.
      filename: 'static/js/[name].[chunkhash:8].js',
      chunkFilename: 'static/js/[name].[chunkhash:8].chunk.js',
      // We inferred the "public path" (such as / or /my-project) from homepage.
      publicPath: publicPath,
      // Point sourcemap entries to original disk location (format as URL on Windows)
      devtoolModuleFilenameTemplate: info =>
        path
          .relative(paths.appSrc, info.absoluteResourcePath)
          .replace(/\\/g, '/'),
    },
    resolve: {
      // This allows you to set a fallback for where Webpack should look for modules.
      // We placed these paths second because we want `node_modules` to "win"
      // if there are any conflicts. This matches Node resolution mechanism.
      // https://github.com/facebookincubator/create-react-app/issues/253
      modules: ['node_modules', paths.appNodeModules].concat(
        // It is guaranteed to exist because we tweak it in `env.js`
        process.env.NODE_PATH.split(path.delimiter).filter(Boolean)
      ),
      // These are the reasonable defaults supported by the Node ecosystem.
      // We also include JSX as a common component filename extension to support
      // some tools, although we do not recommend using it, see:
      // https://github.com/facebookincubator/create-react-app/issues/290
      // `web` extension prefixes have been added for better support
      // for React Native Web.
      extensions: ['.web.js', '.js', '.json', '.web.jsx', '.jsx'],
      alias: {
  
        // Support React Native Web
        // https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
        'react-native': 'react-native-web',
      },
      plugins: [
        // Prevents users from importing files from outside of src/ (or node_modules/).
        // This often causes confusion because we only process files within src/ with babel.
        // To fix this, we prevent you from importing files out of src/ -- if you'd like to,
        // please link the files into your node_modules/ and let module-resolution kick in.
        // Make sure your source files are compiled, as they will not be processed in any way.
        new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
      ],
    },
    module: {
      strictExportPresence: true,
      rules: [
        // TODO: Disable require.ensure as it's not a standard language feature.
        // We are waiting for https://github.com/facebookincubator/create-react-app/issues/2176.
        // { parser: { requireEnsure: false } },
  
        // First, run the linter.
        // It's important to do this before Babel processes the JS.
        {
          test: /\.(js|jsx)$/,
          enforce: 'pre',
          use: [
            {
              options: {
                formatter: eslintFormatter,
                eslintPath: require.resolve('eslint'),
  
              },
              loader: require.resolve('eslint-loader'),
            },
          ],
          include: paths.appSrc,
        },
        {
          // "oneOf" will traverse all following loaders until one will
          // match the requirements. When no loader matches it will fall
          // back to the "file" loader at the end of the loader list.
          oneOf: [
            // "url" loader works just like "file" loader but it also embeds
            // assets smaller than specified size as data URLs to avoid requests.
            {
              test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
              loader: require.resolve('url-loader'),
              options: {
                limit: 10000,
                name: 'static/media/[name].[hash:8].[ext]',
              },
            },
            // Process JS with Babel.
            {
              test: /\.(js|jsx)$/,
              include: paths.appSrc,
              loader: require.resolve('babel-loader'),
              options: {
  
                compact: true,
              },
            },
            // The notation here is somewhat confusing.
            // "postcss" loader applies autoprefixer to our CSS.
            // "css" loader resolves paths in CSS and adds assets as dependencies.
            // "style" loader normally turns CSS into JS modules injecting <style>,
            // but unlike in development configuration, we do something different.
            // `ExtractTextPlugin` first applies the "postcss" and "css" loaders
            // (second argument), then grabs the result CSS and puts it into a
            // separate file in our build process. This way we actually ship
            // a single CSS file in production instead of JS code injecting <style>
            // tags. If you use code splitting, however, any async bundles will still
            // use the "style" loader inside the async code so CSS from them won't be
            // in the main CSS file.
            {
              test: /\.(scss|css)$/,
              loader: ExtractTextPlugin.extract(
                Object.assign(
                  {
                    fallback: require.resolve('style-loader'),
                    use: [
                      {
                        loader: require.resolve('css-loader'),
                        options: {
                          importLoaders: 1,
                          minimize: true,
                          modules: true,
                          sourceMap: shouldUseSourceMap,
                        },
                      },
                      {
                        loader: require.resolve('postcss-loader'),
                        options: {
                          // Necessary for external CSS imports to work
                          // https://github.com/facebookincubator/create-react-app/issues/2677
                          ident: 'postcss',
                          plugins: () => [
                            require('postcss-flexbugs-fixes'),
                            autoprefixer({
                              browsers: [
                                '>1%',
                                'last 4 versions',
                                'Firefox ESR',
                                'not ie < 9', // React doesn't support IE8 anyway
                              ],
                              flexbox: 'no-2009',
                            }),
                          ],
                        },
                      },
                      {
                        loader: 'sass-loader',
                        options: { sourceMap: false }
                      }
                    ],
                  },
                  extractTextPluginOptions
                )
              ),
              // Note: this won't work without `new ExtractTextPlugin()` in `plugins`.
            },
            {
              test: /\.svg$/i,
              use: [
                require.resolve('@shopify/images/icon-loader'),
              ]
            },
            // "file" loader makes sure assets end up in the `build` folder.
            // When you `import` an asset, you get its filename.
            // This loader don't uses a "test" so it will catch all modules
            // that fall through the other loaders.
            {
              loader: require.resolve('file-loader'),
              // Exclude `js` files to keep "css" loader working as it injects
              // it's runtime that would otherwise processed through "file" loader.
              // Also exclude `html` and `json` extensions so they get processed
              // by webpacks internal loaders.
              exclude: [/\.js$/, /\.html$/, /\.json$/],
              options: {
                name: 'static/media/[name].[hash:8].[ext]',
              },
            },
            // ** STOP ** Are you adding a new loader?
            // Make sure to add the new loader(s) before the "file" loader.
          ],
        },
      ],
    },
    plugins: [
      // Makes some environment variables available in index.html.
      // The public URL is available as %PUBLIC_URL% in index.html, e.g.:
      // <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
      // In production, it will be an empty string unless you specify "homepage"
      // in `package.json`, in which case it will be the pathname of that URL.
      new InterpolateHtmlPlugin(env.raw),
      // Generates an `index.html` file with the <script> injected.
      new HtmlWebpackPlugin({
        inject: true,
        template: paths.appHtml,
        minify: {
          removeComments: true,
          collapseWhitespace: true,
          removeRedundantAttributes: true,
          useShortDoctype: true,
          removeEmptyAttributes: true,
          removeStyleLinkTypeAttributes: true,
          keepClosingSlash: true,
          minifyJS: true,
          minifyCSS: true,
          minifyURLs: true,
        },
      }),
      // Makes some environment variables available to the JS code, for example:
      // if (process.env.NODE_ENV === 'production') { ... }. See `./env.js`.
      // It is absolutely essential that NODE_ENV was set to production here.
      // Otherwise React will be compiled in the very slow development mode.
      new webpack.DefinePlugin(env.stringified),
      // Minify the code.
      new webpack.optimize.UglifyJsPlugin({
        compress: {
          warnings: false,
          // Disabled because of an issue with Uglify breaking seemingly valid code:
          // https://github.com/facebookincubator/create-react-app/issues/2376
          // Pending further investigation:
          // https://github.com/mishoo/UglifyJS2/issues/2011
          comparisons: false,
        },
        output: {
          comments: false,
          // Turned on because emoji and regex is not minified properly using default
          // https://github.com/facebookincubator/create-react-app/issues/2488
          ascii_only: true,
        },
        sourceMap: shouldUseSourceMap,
      }),
      // Note: this won't work without ExtractTextPlugin.extract(..) in `loaders`.
      new ExtractTextPlugin({
        filename: cssFilename,
      }),
      // Generate a manifest file which contains a mapping of all asset filenames
      // to their corresponding output file so that tools can pick it up without
      // having to parse `index.html`.
      new ManifestPlugin({
        fileName: 'asset-manifest.json',
      }),
      // Generate a service worker script that will precache, and keep up to date,
      // the HTML & assets that are part of the Webpack build.
      new SWPrecacheWebpackPlugin({
        // By default, a cache-busting query parameter is appended to requests
        // used to populate the caches, to ensure the responses are fresh.
        // If a URL is already hashed by Webpack, then there is no concern
        // about it being stale, and the cache-busting can be skipped.
        dontCacheBustUrlsMatching: /\.\w{8}\./,
        filename: 'service-worker.js',
        logger(message) {
          if (message.indexOf('Total precache size is') === 0) {
            // This message occurs for every build and is a bit too noisy.
            return;
          }
          if (message.indexOf('Skipping static resource') === 0) {
            // This message obscures real errors so we ignore it.
            // https://github.com/facebookincubator/create-react-app/issues/2612
            return;
          }
          console.log(message);
        },
        minify: true,
        // For unknown URLs, fallback to the index page
        navigateFallback: publicUrl + '/index.html',
        // Ignores URLs starting from /__ (useful for Firebase):
        // https://github.com/facebookincubator/create-react-app/issues/2237#issuecomment-302693219
        navigateFallbackWhitelist: [/^(?!\/__).*/],
        // Don't precache sourcemaps (they're large) and build asset manifest:
        staticFileGlobsIgnorePatterns: [/\.map$/, /asset-manifest\.json$/],
      }),
      // Moment.js is an extremely popular library that bundles large locale files
      // by default due to how Webpack interprets its code. This is a practical
      // solution that requires the user to opt into importing specific locales.
      // https://github.com/jmblog/how-to-optimize-momentjs-with-webpack
      // You can remove this if you don't use Moment.js:
      new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
    ],
    // Some libraries import Node modules but don't use them in the browser.
    // Tell Webpack to provide empty mocks for them so importing them works.
    node: {
      dgram: 'empty',
      fs: 'empty',
      net: 'empty',
      tls: 'empty',
    },
  };
  