'use strict'
const path = require('path')
const defaultSettings = require('./src/settings.js')

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

const name = defaultSettings.title || 'vue Admin Template' // page title

// process.env 固定的写法 代表环境变化的前缀 点语法后面的不是固定的
// process.env.port 作为端口号配置的首选方式 环境变量去设置
const port = process.env.port || process.env.npm_config_port || 8082 // dev port

// 区分开发和生产 只有生产环境才进行拆包cdn优化
let externals = {}
let cdn = { css: [], js: [] }
const isProduction = process.env.NODE_ENV === 'production' // 判断是否是生产环境
if (isProduction) {
  externals = {
    'vue': 'Vue',
    'element-ui': 'ELEMENT', // 必须是ELEMENT
    'xlsx': 'XLSX'
  }
  cdn = {
    css: [
      'https://unpkg.com/element-ui/lib/theme-chalk/index.css' // element-ui css 样式表
    ],
    js: [
    // vue must at first!
      'https://unpkg.com/vue@2.6.12/dist/vue.js', // vuejs
      'https://unpkg.com/element-ui@2.15.3/lib/index.js', // element-ui js 变化
      'https://cdn.jsdelivr.net/npm/xlsx@0.16.6/dist/xlsx.full.min.js'
    ]
  }
}
module.exports = {
  // 这里有可能直接配置css js静态资源存放的服务器地址 不是写死的
  publicPath: './',
  outputDir: 'dist',
  assetsDir: 'static',
  lintOnSave: process.env.NODE_ENV === 'development',
  productionSourceMap: false,
  // 配置代理转发 port变量最终会放到devserver
  devServer: {
    port: port, // 配置端口号
    open: true, // 自动打开浏览器
    overlay: {
      warnings: false,
      errors: true
    },
    // 配置中间转发服务
    proxy: {
      '/api': {
        target: 'http://8.142.65.7:3600',
        // target: 'http://ihrm.itheima.net/',
        changeOrigin: true
      }
    }
  },
  configureWebpack: {
    name: name,
    // 排除稳定不变的包
    externals: externals,
    resolve: {
      alias: {
        '@': resolve('src')
      }
    }
  },
  chainWebpack(config) {
    // it can improve the speed of the first screen, it is recommended to turn on preload
    config.plugin('preload').tap(() => [
      {
        rel: 'preload',
        // to ignore runtime.js
        // https://github.com/vuejs/vue-cli/blob/dev/packages/@vue/cli-service/lib/config/app.js#L171
        fileBlacklist: [/\.map$/, /hot-update\.js$/, /runtime\..*\.js$/],
        include: 'initial'
      }
    ])
    // 配置cdn
    // 注入cdn变量 (打包时会执行)
    config.plugin('html').tap(args => {
      args[0].cdn = cdn // 配置cdn给插件
      return args
    })
    // when there are many pages, it will cause too many meaningless requests
    config.plugins.delete('prefetch')

    // set svg-sprite-loader
    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()

    config
      .when(process.env.NODE_ENV !== 'development',
        config => {
          config
            .plugin('ScriptExtHtmlWebpackPlugin')
            .after('html')
            .use('script-ext-html-webpack-plugin', [{
            // `runtime` must same as runtimeChunk name. default is `runtime`
              inline: /runtime\..*\.js$/
            }])
            .end()
          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-elementUI', // 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-commons',
                  test: resolve('src/components'), // can customize your rules
                  minChunks: 3, //  minimum common number
                  priority: 5,
                  reuseExistingChunk: true
                }
              }
            })
          // https:// webpack.js.org/configuration/optimization/#optimizationruntimechunk
          config.optimization.runtimeChunk('single')
        }
      )
  }
}