const path = require("path");
const CompressionPlugin = require("compression-webpack-plugin");
const UglifyJsPlugin = require("uglifyjs-webpack-plugin");
const resolve = dir => {
  return path.join(__dirname, dir);
};
/**
 * 在项目开发的时候将生产环境以及开发环境进行判断
 * 将生产环境中的路径用cdn来进行优化处理
 * 将开发环境中替换为本地的内容，方便处理bug以及开启vueDev
 * 我们可以根据环境变量进行相应的处理，只有在产品的时候，才让插件去自动注入相应的资源文件到html页面
 */
const enableProduction = process.env.NODE_ENV === "production"; // 是否生产环境

let externals = {
  vue: "Vue",
  axios: "axios",
  "vue-router": "VueRouter",
  vuex: "Vuex",
  "view-design": "iview",
  "vue-lazyload": "VueLazyload",
  "js-cookie": "Cookies",
  wangeditor: "wangEditor",
  "sockjs-client": "SockJS",
  "@antv/g2": "G2",
  dplayer: "DPlayer"
};

// 使用CDN的内容
let cdn = {
  css: ["https://cdn.jsdelivr.net/npm/view-design@4.1.1/dist/styles/iview.css"],
  js: [
    // vue must at first!
    "https://cdn.jsdelivr.net/npm/vue@2.6.11/dist/vue.min.js",
    "https://cdn.jsdelivr.net/npm/vuex@3.1.2/dist/vuex.min.js",
    "https://cdn.jsdelivr.net/npm/vue-router@3.1.3/dist/vue-router.min.js",
    "https://cdn.jsdelivr.net/npm/axios@0.19.0/dist/axios.min.js",
    "https://cdn.jsdelivr.net/npm/view-design@4.1.1/dist/iview.min.js",
    "https://cdn.jsdelivr.net/npm/vue-lazyload@1.3.3/vue-lazyload.min.js",
    "https://cdn.jsdelivr.net/npm/js-cookie@2.2.1/src/js.cookie.min.js",
    "https://cdn.jsdelivr.net/npm/dplayer@1.25.0/dist/DPlayer.min.js",
    "https://cdn.jsdelivr.net/npm/wangeditor@latest/dist/wangEditor.min.js",
    "https://cdn.jsdelivr.net/npm/sockjs-client@1/dist/sockjs.min.js",
    "https://gw.alipayobjects.com/os/lib/antv/g2/4.1.24/dist/g2.min.js"
  ]
};

// 删除注释
let jsPlugin = [
  new UglifyJsPlugin({
    uglifyOptions: {
      // 删除注释
      output: {
        comments: false
      },
      compress: {
        drop_console: true, // 删除所有调式带有console的
        drop_debugger: true,
        pure_funcs: ["console.log"] // 删除console.log
      }
    }
  })
];

// 判断是否需要加载CDN，线上删除注释
cdn = enableProduction ? cdn : { css: [], js: [] };
externals = enableProduction ? externals : {};
jsPlugin = enableProduction ? jsPlugin : [];
module.exports = {
  css: {
    loaderOptions: {
      // 向 CSS 相关的 loader 传递选项
      less: {
        lessOptions: {
          javascriptEnabled: true
        }
      }
    }
  },
  devServer: {
    port: 10003
  },

  // 打包时不生成.map文件 避免看到源码
  productionSourceMap: false,

  // 部署优化
  configureWebpack: {
    // 使用CDN
    externals: externals,
    // GZIP压缩
    plugins: [
      new CompressionPlugin({
        test: /\.js$|\.html$|\.css/, // 匹配文件
        threshold: 10240 // 对超过10k文件压缩
      })
    ],
    optimization: {
      runtimeChunk: "single",
      minimizer: jsPlugin,
      splitChunks: {
        chunks: "all",
        maxInitialRequests: Infinity,
        minSize: 20000,
        cacheGroups: {
          vendor: {
            test: /[\\/]node_modules[\\/]/,
            name(module) {
              // get the name. E.g. node_modules/packageName/not/this/part.js
              // or node_modules/packageName
              const packageName = module.context.match(
                /[\\/]node_modules[\\/](.*?)([\\/]|$)/
              )[1];
              // npm package names are URL-safe, but some servers don't like @ symbols
              return `npm.${packageName.replace("@", "")}`;
            }
          }
        }
      }
    }
  },
  // 将cdn的资源挂载到插件上
  chainWebpack(config) {
    //  @ 对应 src目录
    config.resolve.alias.set("@", resolve("src"));
    config.plugin("html").tap(args => {
      args[0].cdn = cdn;
      return args;
    });
  },

  pluginOptions: {
    "style-resources-loader": {
      preProcessor: "scss",
      patterns: [path.resolve(__dirname, "./src/styles/common.scss")]
    }
  }
};