/**
 * 框架核心
 * @author yutent<yutent.io@gmail.com>
 * @date 2020/09/28 10:01:47
 */

import 'es.shim' // 加载拓展方法
import http from 'node:http'
import { parse, join } from 'node:path'
import fs from 'iofs'

import Request from '@gm5/request'
import Response from '@gm5/response'

import { noop, readonlyProp } from './lib.js'
import config from './config/index.js'

import { createCors } from './middleware/cors.js'
import { createRouter } from './middleware/router.js'

process.on('uncaughtException', err => {
  console.error('UncaughtException: ', err)
})

class Five {
  #config = config
  #modules = {}
  #middlewares = [createCors()]

  #server = null

  constructor() {
    readonlyProp(this, 'state', Object.create(null))
  }

  async #loop(req, res, idx = 0) {
    let fn = this.#middlewares[idx]
    if (fn) {
      await fn.call(this, req, res, _ => {
        idx++
        this.#loop(req, res, idx)
      })
    }
  }

  /*------------------------------------------------------------------------*/

  get server() {
    return this.#server
  }

  /*------------------------------------------------------------------------*/

  // 注册属性到全局Five对象
  set(obj) {
    for (let i in obj) {
      if (typeof obj[i] === 'object' && !Array.isArray(obj[i])) {
        if (!this.#config[i]) {
          this.#config[i] = obj[i]
        } else {
          try {
            Object.assign(this.#config[i], obj[i])
          } catch (err) {
            console.error(err)
          }
        }
      } else {
        this.#config[i] = obj[i]
      }
    }
    return this
  }

  // 获取全局配置
  get(key) {
    return this.#config[key]
  }

  // 加载中间件
  // 与别的中间件用法有些不一样, 回调的传入参数中的req和res,
  // 并非原生的request对象和response对象,
  // 而是框架内部封装过的,可通过origin属性访问原生的对象
  use(fn = noop) {
    if (typeof fn === 'function') {
      this.#middlewares.push(fn)
      return this
    }
    throw TypeError('argument must be a function')
  }

  // 注入实例化对象到实例池中
  // 与use方法不同的是, 这个会在server创建之前就已经执行
  install({ name, install }, args) {
    this['$$' + name] = install.call(this, args)
    return this
  }

  // 预加载应用, 缓存以提高性能
  preload(dir) {
    let list = fs.ls(dir)

    if (list) {
      list.forEach(item => {
        let { name } = parse(item)
        if (name.startsWith('.')) {
          return
        }
        // 如果是目录,则默认加载index.js, 其他文件不加载
        // 交由index.js自行处理, 用于复杂的应用
        if (fs.isdir(item)) {
          item = join(item, './index.js')
        }

        this.#modules[name] = import(item)
          .then(r => r.default)
          .catch(err => {
            console.error(err)
            return null
          })
      })
    }

    return this
  }

  $load(name) {
    return this.#modules[name]
  }

  // 启动http服务
  listen(port) {
    this.set({ port })
    return this
  }

  run() {
    this.#server = http.createServer()

    // 路由中间件要在最后
    this.use(createRouter())

    this.#server
      .on('request', (req, res) => {
        let request = new Request(req, res)
        let response = new Response(req, res)

        if (response.ended) {
          return
        }

        response.set('X-Powered-By', this.get('X-Powered-By') || 'Five.js')

        this.#loop(request, response)
      })
      .on('listening', _ => {
        if (this.get('debug')) {
          console.log('Server successfully started ...')
          console.log('%s://%s:%d\n', 'http', '127.0.0.1', this.get('port'))
        }
      })
      .on('error', err => {
        console.error(err)
      })
      .listen(this.get('port'))

    return this
  }
}

export function createApp(conf = {}) {
  let app = new Five()
  app.set(conf)
  return app
}