// Imports
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin')
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const BabelRegister = require("babel-register");
const UglifyJsPlugin = require("uglifyjs-webpack-plugin");
const OptimizeCSSAssetsPlugin = require("optimize-css-assets-webpack-plugin");

const devMode = process.env.NODE_ENV !== 'production'

// Webpack Configuration
const config = {

  // Entry
  entry: './src/app.js',

  // Output
  output: {
    path: path.resolve(__dirname, './dist'),
    filename: '[name].[chunkhash].js'
  },
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        cache: true,
        parallel: true,
        sourceMap: true, // set to true if you want JS source maps
        uglifyOptions: {
          output: {
            comments: false
          }
        }
      }),
      new OptimizeCSSAssetsPlugin({})
    ],
    splitChunks: {
			cacheGroups: {
				commons: {
					chunks: "initial",
					minChunks: 2,
					maxInitialRequests: 5,
					minSize: 0 
				},
				vendor: {
					test: /node_modules/,
					chunks: "initial",
					name: "vendor",
					priority: 10,
					enforce: true
				}
			}
		}
  },
  module: {
    rules : [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      },
      // CSS Files
      {
        test: /\.(sa|sc|c)ss$/,
        use: [
          devMode ? 'style-loader' : MiniCssExtractPlugin.loader,
          'css-loader',
          //'postcss-loader',
          'sass-loader',
        ]
      },
      {
        test: /\.(png|jpg|gif|svg)$/i,
        use: [
          {
            loader: 'url-loader',
            options: {
              limit: 8192
            }
          }
        ]
      }
    ]
  },

  // Plugins
  plugins: [
    new HtmlWebpackPlugin({
      template: './src/template.html',
      filename: 'index.html',
      hash: true
    }),
    new MiniCssExtractPlugin({
      filename: devMode ? '[name].css' : '[name].[hash].css',
      chunkFilename: devMode ? '[id].css' : '[id].[hash].css',
    })
  ],

  // OPTIONAL
  // Reload On File Change
  watch: true,
  // Development Tools (Map Errors To Source File)
  devtool: 'source-map',
};

// Exports
module.exports = config;