var path = require('path')
var config = require('../config')
var utils = require('./utils')
var webpack = require('webpack')
var merge = require('webpack-merge')
var baseWebpackConfig = require('./webpack.base.conf')
var MiniCssExtractPlugin = require('mini-css-extract-plugin')
const CssMinimizerPlugin = require("css-minimizer-webpack-plugin")
var HtmlWebpackPlugin = require('html-webpack-plugin')
var env = process.env.NODE_ENV === 'testing'
    ? require('../config/test.env')
    : config.build.env

let commitHash = (() => {
  const subst = "$Format:%h$";
  if(!subst.match(/Format:/)) {
    return subst;
  } else {
    return require('child_process')
      .execSync('git rev-parse --short HEAD')
      .toString();
  }
})();

var webpackConfig = merge(baseWebpackConfig, {
  mode: 'production',
  module: {
    rules: utils.styleLoaders({ sourceMap: config.dev.cssSourceMap, extract: true })
  },
  devtool: config.build.productionSourceMap ? 'source-map' : false,
  optimization: {
    minimize: true,
    splitChunks: {
      chunks: 'all'
    },
    minimizer: [
      `...`,
      new CssMinimizerPlugin()
    ]
  },
  output: {
    path: config.build.assetsRoot,
    filename: utils.assetsPath('js/[name].[chunkhash].js'),
    chunkFilename: utils.assetsPath('js/[name].[chunkhash].js')
  },
  plugins: [
    // http://vuejs.github.io/vue-loader/workflow/production.html
    new webpack.DefinePlugin({
      'process.env': env,
      'COMMIT_HASH': JSON.stringify(commitHash),
      'DEV_OVERRIDES': JSON.stringify(undefined),
      '__VUE_OPTIONS_API__': true,
      '__VUE_PROD_DEVTOOLS__': false
    }),
    // extract css into its own file
    new MiniCssExtractPlugin({
      filename: utils.assetsPath('css/[name].[contenthash].css')
    }),
    // generate dist index.html with correct asset hash for caching.
    // you can customize output by editing /index.html
    // see https://github.com/ampedandwired/html-webpack-plugin
    new HtmlWebpackPlugin({
      filename: process.env.NODE_ENV === 'testing'
        ? 'index.html'
        : config.build.index,
      template: 'index.html',
      inject: true,
      minify: {
        removeComments: true,
        collapseWhitespace: true,
        removeAttributeQuotes: true,
        ignoreCustomComments: [/server-generated-meta/]
        // more options:
        // https://github.com/kangax/html-minifier#options-quick-reference
      }
    }),
    // split vendor js into its own file
    // extract webpack runtime and module manifest to its own file in order to
    // prevent vendor hash from being updated whenever app bundle is updated
    // new webpack.optimize.SplitChunksPlugin({
    // name: ['app', 'vendor']
    // }),
  ]
})

if (config.build.productionGzip) {
  var CompressionWebpackPlugin = require('compression-webpack-plugin')

  webpackConfig.plugins.push(
    new CompressionWebpackPlugin({
      asset: '[path].gz[query]',
      algorithm: 'gzip',
      test: new RegExp(
        '\\.(' +
        config.build.productionGzipExtensions.join('|') +
        ')$'
      ),
      threshold: 10240,
      minRatio: 0.8
    })
  )
}

module.exports = webpackConfig