const merge = require('webpack-merge');
const common = require('./webpack.common.config.js');

const HtmlWebpackPlugin = require('html-webpack-plugin');
const { CleanWebpackPlugin } = require('clean-webpack-plugin');
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const OptimizeCssAssetsPlugin = require('optimize-css-assets-webpack-plugin');
const TerserPlugin = require('terser-webpack-plugin');
module.exports = merge(common, {
  mode: 'production',
  output: {
    filename: 'js/[name].[chunkhash:8].js',
  },
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [MiniCssExtractPlugin.loader, 'css-loader', 'postcss-loader'],
      },
      {
        test: /\.less$/,
        use: [
          MiniCssExtractPlugin.loader,
          'css-loader',
          'less-loader',
          'postcss-loader',
        ],
      },
      // {
      //   test: /\.(scss|sass)$/,
      //   use: [
      //     MiniCssExtractPlugin.loader,
      //     'css-loader',
      //     'postcss-loader',
      //     'sass-loader'
      //   ]
      // },
    ],
  },
  plugins: [
    new HtmlWebpackPlugin({
      filename: 'index.html',
      template: 'public/index.html',
      inject: 'body',
      minify: {
        removeComments: true,
        collapseWhitespace: true,
      },
    }),
    new CleanWebpackPlugin(),
    new MiniCssExtractPlugin({
      filename: 'css/[name].[hash].css',
      chunkFilename: 'css/[id].[hash].css',
    }),
  ],
  optimization: {
    minimizer: [
      new UglifyJsPlugin(),
      new OptimizeCssAssetsPlugin({
        assetNameRegExp: /\.css$/g,
        cssProcessor: require('cssnano'),
        cssProcessorPluginOptions: {
          preset: ['default', { discardComments: { removeAll: true } }],
        },
        canPrint: true,
      }),
      // This is only used in production mode
      new TerserPlugin({
        terserOptions: {
          parse: {
            // We want terser to parse ecma 8 code. However, we don't want it
            // to apply any minification steps that turns valid ecma 5 code
            // into invalid ecma 5 code. This is why the 'compress' and 'output'
            // sections only apply transformations that are ecma 5 safe
            // https://github.com/facebook/create-react-app/pull/4234
            ecma: 8,
          },
          compress: {
            ecma: 5,
            warnings: false,
            // Disabled because of an issue with Uglify breaking seemingly valid code:
            // https://github.com/facebook/create-react-app/issues/2376
            // Pending further investigation:
            // https://github.com/mishoo/UglifyJS2/issues/2011
            comparisons: false,
            // Disabled because of an issue with Terser breaking valid code:
            // https://github.com/facebook/create-react-app/issues/5250
            // Pending further investigation:
            // https://github.com/terser-js/terser/issues/120
            inline: 2,
          },
          mangle: {
            safari10: true,
          },
          // Added for profiling in devtools
          keep_classnames: true,
          keep_fnames: true,
          output: {
            ecma: 5,
            comments: false,
            // Turned on because emoji and regex is not minified properly using default
            // https://github.com/facebook/create-react-app/issues/2488
            ascii_only: true,
          },
        },
        sourceMap: true,
      }),
    ],
    splitChunks: {
      chunks: 'all',
      minSize: 30000,
      maxSize: 0,
      minChunks: 1,
      cacheGroups: {
        framework: {
          test: 'framework',
          name: 'framework',
          enforce: true,
        },
        vendors: {
          priority: -10,
          test: /node_modules/,
          name: 'vendor',
          enforce: true,
        },
      },
    },
  },
});