const path = require("path");
const TerserPlugin = require("terser-webpack-plugin");

const IS_PROD = process.env.NODE_ENV === "production";

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

const CDN = {
  externals: {
    vue: "Vue",
    "element-ui": "ELEMENT",
    "bpmn-js/lib/Modeler": "BpmnJS"
  },
  css: [],
  js: [
    "https://unpkg.com/bpmn-js@^7.4.0/dist/bpmn-modeler.development.js",
    "https://cdn.bootcdn.net/ajax/libs/vue/2.6.12/vue.min.js",
    "https://cdn.bootcdn.net/ajax/libs/element-ui/2.15.0/index.min.js"
  ]
};

module.exports = {
  publicPath: IS_PROD ? "././" : "/", // 打包相对路径
  productionSourceMap: false,
  devServer: {
    port: 8100
  },
  chainWebpack: config => {
    // ============注入cdn start============
    config.plugin("html").tap(args => {
      // 生产环境或本地需要cdn时，才注入cdn
      if (IS_PROD) args[0].cdn = CDN;
      return args;
    });
    // ============注入cdn start============

    config
      // https://webpack.js.org/configuration/devtool/#development
      .when(process.env.NODE_ENV === "development", config => config.devtool("source-map"));

    config.when(process.env.NODE_ENV !== "development", config => {
      config.optimization.splitChunks({
        chunks: "all",
        cacheGroups: {
          libs: {
            name: "chunk-libs",
            test: /[\\/]node_modules[\\/]/,
            priority: 10,
            chunks: "initial" // only package third parties that are initially dependent
          },
          // elementUI: {
          //   name: "chunk-element-ui", // split elementUI into a single package
          //   priority: 20, // the weight needs to be larger than libs and app or it will be packaged into libs or app
          //   test: /[\\/]node_modules[\\/]_?element-ui(.*)/ // in order to adapt to cnpm
          // },
          commons: {
            name: "chunk-components",
            test: resolve("package"), // can customize your rules
            minChunks: 1, //  minimum common number
            priority: 5,
            reuseExistingChunk: true
          }
        }
      });
      config.optimization.runtimeChunk("single");
    });
  },
  configureWebpack: config => {
    // 生产环境相关配置
    if (IS_PROD) {
      // cdn
      config.externals = CDN.externals;

      // 代码混淆
      config.plugins.push(new TerserPlugin());
    }
  }
};