"use strict";
const path = require("path");
// 代码压缩
const TerserPlugin = require('terser-webpack-plugin')
// gzip压缩
const CompressionWebpackPlugin = require('compression-webpack-plugin')
// 是否为生产环境
const isProduction = process.env.NODE_ENV !== 'development'


function resolve (dir) {
  return path.join(__dirname, dir);
}

console.log(process.env)

module.exports = {
  productionSourceMap: false,
  lintOnSave: false,
  configureWebpack: {
    output: { // 输出重构  打包编译后的 文件名称  【模块名称.版本号.时间戳】
      filename: `[name].${new Date().getTime()}.js`,
      chunkFilename: `[name].${new Date().getTime()}.js`
    }
  },
  chainWebpack: config => {
    // 使用svg-sprite-loader加载icon图标
    config.module
      .rule("svg")
      .exclude.add(resolve("src/icons"))
      .end();
    config.module
      .rule("icons")
      .test(/\.svg$/)
      .include.add(resolve("src/icons"))
      .end()
      .use("svg-sprite-loader")
      .loader("svg-sprite-loader")
      .options({
        symbolId: "icon-[name]"
      })
      .end();
    // 图片压缩
    if (isProduction) {
      // 删除预加载
      config.plugins.delete('preload');
      config.plugins.delete('prefetch');
      // 压缩代码
      config.optimization.minimize(true);
      // 分割代码
      config.optimization.splitChunks({
        chunks: 'all'
      })
    }
  },
  configureWebpack: config => {
    // 生产环境相关配置
    if (isProduction) {
      // 代码压缩
      config.plugins.push(
        new TerserPlugin({
          terserOptions: {
            //生产环境自动删除console
            compress: {
              warnings: false, // 若打包错误，则注释这行
              drop_debugger: true,
              drop_console: true,
              pure_funcs: ['console.log']
            }
          },
          sourceMap: false,
          parallel: true
        })
      )

      // gzip压缩
      const productionGzipExtensions = ['html', 'js', 'css']
      config.plugins.push(
        new CompressionWebpackPlugin({
          filename: '[path].gz[query]',
          algorithm: 'gzip',
          test: new RegExp(
            '\\.(' + productionGzipExtensions.join('|') + ')$'
          ),
          threshold: 10240, // 只有大小大于该值的资源会被处理 10240
          minRatio: 0.8, // 只有压缩率小于这个值的资源才会被处理
          deleteOriginalAssets: false // 删除原文件
        })
      )

      // 公共代码抽离
      config.optimization = {
        splitChunks: {
          cacheGroups: {
            vendor: {
              chunks: 'all',
              test: /node_modules/,
              name: 'vendor',
              minChunks: 1,
              maxInitialRequests: 5,
              minSize: 0,
              priority: 100
            },
            common: {
              chunks: 'all',
              test: /[\\/]src[\\/]js[\\/]/,
              name: 'common',
              minChunks: 2,
              maxInitialRequests: 5,
              minSize: 0,
              priority: 60
            },
            styles: {
              name: 'styles',
              test: /\.(sa|sc|c)ss$/,
              chunks: 'all',
              enforce: true
            },
            runtimeChunk: {
              name: 'manifest'
            }
          }
        }
      }
    }
  }
};