const path = require('path');

// css extraction and minification
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const CssMinimizerPlugin = require("css-minimizer-webpack-plugin");

// clean out build dir in-between builds
const { CleanWebpackPlugin } = require('clean-webpack-plugin');

module.exports = (env, argv) => {
  return {
    entry: {
      'main': [
        './src/assets/js/main.js',
        './src/assets/sass/main.scss'
      ]
    },
    target: ['web', 'es5'],
    output: {
      filename: './public/js/[name].min.js',
      path: path.resolve(__dirname)
    },
    devtool: "source-map",
    module: {
      rules: [
        // js babelization
        {
          test: /\.(js|jsx)$/,
          exclude: /node_modules/,
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env'],
          }
        },
        // sass compilation
        {
          test: /\.(sass|scss)$/,
          use: [
            MiniCssExtractPlugin.loader, 
            {
              loader: "css-loader",
              options: {
                sourceMap: true,
              },
            },
            {
              loader: "sass-loader",
              options: {
                sourceMap: true,
              },
            }
          ]
        },
        // loader for webfonts (only required if loading custom fonts)
        {
          test: /\.(woff|woff2|eot|ttf|otf)$/,
          type: 'src/assets/fonts',
          generator: {
            filename: './public/fonts/[name][ext]',
          }
        },
        // loader for images and icons (only required if css references image files)
        {
          test: /\.(png|jpg|gif)$/,
          type: 'src/assets/img',
          generator: {
            filename: './public/img/[name][ext]',
          }
        },
      ]
    },
    plugins: [
      // clear out build directories on each build
      new CleanWebpackPlugin({
        cleanOnceBeforeBuildPatterns: [
          './public/js/*',
          './public/css/*'
        ]
      }),
      // css extraction into dedicated file
      new MiniCssExtractPlugin({
        filename: './public/css/main.min.css'
      }),
    ],
    optimization: {
      // minification - only performed when mode = production
      minimizer: [
        // js minification - special syntax enabling webpack 5 default terser-webpack-plugin 
        `...`,
        // css minification
        new CssMinimizerPlugin(),
      ]
    },
  }
};