const HtmlWebpackPlugin = require('html-webpack-plugin')

  plugins: [
    new HtmlWebpackPlugin({
      template: path.resolve(__dirname, 'index.html'),    //需要被打包的html
      filename: 'index.html',  //文件打包名
      title: '手动搭建vue' //html传进去的变量
    }),
  ]

const { VueLoaderPlugin } = require('vue-loader')

  module: {
    rules: [
      {
        test: /\.vue$/,  //.vue后缀的文件
        use: ['vue-loader']  //启用vue-loader
      }
    ]
  },
  plugins: [
    new VueLoaderPlugin()
  ]

module.exports={
  presets:[
    ['@babel/preset-env',{
      'targets':{
        'browsers':['last 2 versions']
      }
    }]
  ]
}

devServer: { 
    static:{
      directory: path.resolve(__dirname, './dist')
    },
    port:8080,  //端口
    hot: true, //自动打包
    host:'localhost', 
    open:true //自动跳到浏览器
  }

const fs = require('fs');
const path = require('path');
const parser = require('@babel/parser')
const traverse = require('@babel/traverse').default
const babel = require('@babel/core')


const getModuleInfo = (file) => {
  //1 读文件
  const body = fs.readFileSync(file, 'utf8');  //读到路径下的文件内容

  //2 分析文件转AST树
  const ast = parser.parse(body, {   //body为需要解析的代码
    sourceType: 'module' //以es6的模块化语法解析
  })
  // console.log(ast.program.body);  //[{},{},{}...]

  //3 依赖收集 
  const deps = {}
  traverse(ast, { //遍历ast
    ImportDeclaration({ node }) {  //把import类型的对象找出来
      const dirname = path.dirname(file)  //拿到index.js所在文件夹路径
      const abspath = './' + path.posix.join(dirname, node.source.value) //add.js文件的绝对路径
      deps[node.source.value] = abspath //key:'./add.js'  value:'xxx/add.js'
    }
  })

  //4.把ast->code
  const { code } = babel.transformFromAst(ast, null, {
    presets: ['@babel/preset-env']
  })
  console.log(code);

  const moduleInfo = { file, deps, code }
  return moduleInfo
}

//5. 递归获取所有依赖
const parseModules = (file) => {
  const entry = getModuleInfo(file)
  const temp = [entry]
  const depsGraph = {}

  for (let i = 0; i < temp.length; i++) {
    const deps = temp[i].deps //{ './add.js': './src/add.js', './minus.js': './src/minus.js' }
    if (deps) {
      for (const key in deps) {
        if (deps.hasOwnProperty(key)) {
          temp.push(getModuleInfo(deps[key]))
        }
      }
    }
  }

  temp.forEach(moduleInfo => {
    depsGraph[moduleInfo.file] = {
      deps: moduleInfo.deps,
      code: moduleInfo.code
    }
  })
  // console.log(temp);
  return depsGraph
}

//打包
const bundle = (file) => {
  const depsGraph = JSON.stringify(parseModules(file));
  //手写一个require 借助eval
  return `(function(grash) {

    function require(file) {
      function absRequire(relPath) {
        return require(grash[file].deps[relPath])
      }

      var exports = {};

      (function(require, code) {
        eval(code)
      })(absRequire, grash[file].code)

      return exports
    }

    require('${file}')

  })(${depsGraph})`

}

const result=bundle('./src/index.js')
fs.mkdirSync('./dist')
fs.writeFileSync('./dist/bundle.js', result)

//用node启一个服务
const Koa = require('koa');
const app = new Koa()
const fs = require('fs')
const path = require('path')
const compilerDom = require('@vue/compiler-dom')  //引入vue源码  能识别template中的代码
const compilerSfc = require('@vue/compiler-sfc')  // 能识别script中的代码

function rewriteImport(content) {
  return content.replace(/ from ['|"]([^'"]+)['|"]/g, (s0, s1) => {
    //若以 ./  ../  / 开头的相对路径
    console.log(s0, s1);
    if (s1[0] !== '.' && s1[0] !== '/') {   //'vue
      return ` from '/@modules/${s1}'`   //去http://localhost:5173/@modules/vue
    } else {
      return s0
    }
  })
}

app.use((ctx) => {
  const { request: { url, query } } = ctx
  if (url === '/') {
    //读index.html
    ctx.type = 'text/html'  //设置类型
    let content = fs.readFileSync('./index.html', 'utf8')  //读文件
    // console.log(content);

    ctx.body = content//content输出给前端
  }
  else if (url.endsWith('.js')) {  //js文件  /src/main.js
    const p = path.resolve(__dirname, url.slice(1))  //   src/main.js  拿到文件的绝对路径
    ctx.type = 'application/javascript'
    const content = fs.readFileSync(p, 'utf8')
    ctx.body = rewriteImport(content)
  }
  else if (url.startsWith('/@modules')) { //  '/@modules/vue'
    const prefix = path.resolve(__dirname, 'node_modules', url.replace('/@modules/', ''))  // 'vue'
    const module = require(prefix + '/package.json').module //读取package.json中的module字段   拿到vue的模块源码地址
    const p = path.resolve(prefix, module)  // 拿到vue的模块源码的终极地址
    const ret = fs.readFileSync(p, 'utf8')  //读取文件
    ctx.type = 'application/javascript'
    ctx.body = rewriteImport(ret)  //递归 防止vue源码又用到了其它模块
  }
  else if (url.indexOf('.vue') > -1) {
    const p = path.resolve(__dirname, url.split('?')[0].slice(1)) // src/App.vue
    const { descriptor } = compilerSfc.parse(fs.readFileSync(p, 'utf8'))
    
    console.log(descriptor);
    if (!query.type) { // 返回.vue文件的js部分
      ctx.type = 'application/javascript'
      ctx.body = `
        ${rewriteImport(descriptor.script.content.replace('export default ', 'const __script = '))}
        import { render as __render } from "${url}?type=template"
        __script.render = __render
        export default __script
      `
    } else if (query.type === 'template') { // 返回.vue文件的html部分
      const template = descriptor.template
      const render = compilerDom.compile(template.content, {mode: 'module'}).code
      ctx.type = 'application/javascript'
      ctx.body = rewriteImport(render)
    }

  }
  else if (url.endsWith('.css')) {
    const p = path.resolve(__dirname, url.slice(1))
    const file = fs.readFileSync(p, 'utf8')
    const content = `
      const css="${file.replace(/\n/g, '')}"
      let link=document.createElement('style')
      link.setAttribute('type','text/css')
      document.head.appendChild(link)
      link.innerHTML = css
      export default css
    `
    ctx.type = "application/javascript"
    ctx.body = content
  }
})

app.listen(5173, () => {
  console.log('listening on port 5173');
})