import * as OptimizeCSSAssetsPlugin from "optimize-css-assets-webpack-plugin";
import * as TerserPlugin from "terser-webpack-plugin";
// import * as webpack from "webpack";

export const minimizerPluginMap = {
  terser: ({ shouldUseSourceMap }: { shouldUseSourceMap: boolean }) =>
    new TerserPlugin({
      terserOptions: {
        parse: {
          // we want terser to parse ecma 8 code. However, we don't want it
          // to apply any minfication 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,
        },
        ecma: 5,
        compress: {
          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 futher investigation:
          // https://github.com/terser-js/terser/issues/120
          inline: 2,
        },
        mangle: {
          safari10: 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,
        },
      },
      // Use multi-process parallel running to improve the build speed
      // Default number of concurrent runs: os.cpus().length - 1
      parallel: true,
      // Enable file caching
      cache: true,
      sourceMap: shouldUseSourceMap,
    }),
  optimizeCssAssetsPlugin: ({ shouldUseSourceMap }: { shouldUseSourceMap: boolean }) =>
    new OptimizeCSSAssetsPlugin({
      cssProcessorOptions: {
        parser: require("postcss-safe-parser"),
        map: shouldUseSourceMap
          ? {
              // `inline: false` forces the sourcemap to be output into a
              // separate file
              inline: false,
              // `annotation: true` appends the sourceMappingURL to the end of
              // the css file, helping the browser find the sourcemap
              annotation: true,
            }
          : false,
      },
    }),
};