const path = require('path')

// gzip压缩插件
const CompressionWebpackPlugin = require('compression-webpack-plugin')

// 代码打包之后取出console.log压缩代码
const TerserPlugin = require('terser-webpack-plugin')

// 图形化打包详情
const BundleAnalyzer = require('webpack-bundle-analyzer').BundleAnalyzerPlugin

const cdn = {
// 忽略打包的第三方库
externals: {
vue: 'Vue',
vuex: 'Vuex',
'vue-router': 'VueRouter',
axios: 'axios'
},
// 通过cdn方式使用
js: [
'https://cdn.bootcss.com/vue/2.6.11/vue.runtime.min.js',
'https://cdn.bootcss.com/vue-router/3.1.2/vue-router.min.js',
'https://cdn.bootcss.com/vuex/3.1.2/vuex.min.js',
'https://cdn.bootcss.com/axios/0.19.2/axios.min.js',
'https://cdn.bootcss.com/moment.js/2.24.0/moment.min.js',
'https://cdn.bootcss.com/echarts/3.7.1/echarts.min.js'
],
css: []
}

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

module.exports = {
// 是否触发eslint检查
lintOnSave: false,
publicPath: '/',
// 打包文件的出口
outputDir: 'dist',
// 放置生成的css和js和img和fonts的目录
assetsDir: 'static',
// 存放index.html模板的路径
indexPath: 'static/index.html',
productionSourceMap: false,
chainWebpack: config => {
// 配置cdn引入
config.plugin('html').tap(args => {
args[0].cdn = cdn
return args
})

// 移除prefetch插件，避免加载多余的资源
config.plugins.delete('prefetch')

// 定义文件夹的路径
config.resolve.alias
  .set('@', resolve('src'))
  .set('assets', resolve('src/assets'))
  .set('components', resolve('src/components'))
  .set('router', resolve('src/router'))
  .set('store', resolve('src/store'))
  .set('views', resolve('src/views'))

// 压缩图片
const imagesRule = config.module.rule('images')
imagesRule.uses.clear()
imagesRule.use('file-loader')
  .loader('url-loader')
  .options({
    limit: 10240,
    fallback: {
      loader: 'file-loader',
      options: {
        outputPath: 'static/images'
      }
    }
  })

// 压缩响应的app.json返回的代码压缩
config.optimization.minimize(true)

},
// webpack的配置
configureWebpack: config => {
// 忽略打包配置
config.externals = cdn.externals
// 生产环境配置
if (process.env.NODE_ENV === 'production') {
// 代码压缩去除console.log
config.plugins.push(
new TerserPlugin({
terserOptions: {
ecma: undefined,
warnings: false,
parse: {},
compress: {
drop_console: true,
drop_debugger: false,
pure_funcs: ['console.log'] // 移除console
}
}
})
)
}

// 开启gzip压缩
config.plugins.push(
  new CompressionWebpackPlugin(
    {
      filename: info => {
        return `${info.path}.gz${info.query}`
      },
      algorithm: 'gzip',
      threshold: 10240, // 只有大小大于该值的资源会被处理 10240
      test: new RegExp('\\.(' + ['js'].join('|') + ')$'
      ),
      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
    }
  )
)

// 展示打包图形化信息
config.plugins.push(
  new BundleAnalyzer()
)

// 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
      }
    }
  }
}

},
css: {
extract: true,
sourceMap: false,
loaderOptions: {
// 定义全局scss无需引入即可使用
sass: {
prependData: @import "@/assets/css/variable.scss"; @import "@/assets/css/common.scss"; @import "@/assets/css/mixin.scss";
}
}
},
// 需要gzip压缩的文件
devServer: {
host: 'localhost',
port: 8080, // 端口号
open: false, // 配置自动启动浏览器
before (app, server) {
app.get(/.*.(js)$/, (req, res, next) => {
req.url = req.url + '.gz'
res.set('Content-Encoding', 'gzip')
next()
})
}
}

}