奋斗的宽

01const http = require('http')
02const { Stream } = require('stream')
03const qs = require('querystring')
04
05const app = {
06  middleware: [],
07  use(fn) {
08    this.middleware.push(fn)
09  },
10  listen(port = 3000) {
11    const server = http.createServer(this.callback.bind(this))
12    return server.listen(port)
13  },
14  async callback(req, res) {
15    console.log('start')
16    const fn = compose(this.middleware)
17    // 这里有很多代理的方法
18    const ctx = {
19      request: req,
20      response: res,
21      req,
22      res,
23      get query() {
24        return { ...qs.parse(req.url.split('?')[1] || '') }
25      },
26    }
27    await fn(ctx)
28      .then(() => {
29        const { body } = ctx
30        if (!body) return res.end('null')
31        if (Buffer.isBuffer(body)) return res.end(body)
32        if (typeof body === 'string') return res.end(body)
33        if (body instanceof Stream) return body.pipe(res)
34        return res.end(JSON.stringify(body))
35      })
36      .catch((error) => {
37        res.end(error.toString())
38      })
39    console.log('end')
40  },
41}
42
43function compose(middleware = []) {
44  let index = -1
45
46  return (ctx, next) => {
47    return dispatch(0)
48    function dispatch(i) {
49      if (i <= index) return Promise.reject(new Error('next() called multile times'))
50      index = i
51      let fn = middleware[i]
52      if (i === middleware.length) fn = next
53      if (!fn) return Promise.resolve()
54      try {
55        return Promise.resolve(fn(ctx, dispatch.bind(null, i + 1)))
56      } catch (err) {
57        return Promise.reject(err)
58      }
59    }
60  }
61}
62
63module.exports = app
64

01// const fs = require('fs')
02const app = require('./app')
03
04app.use(async function test1(ctx, next) {
05  console.log(1)
06  console.log('query', ctx.query)
07  await next()
08  console.log(6)
09})
10app.use(async function test2(ctx, next) {
11  console.log(2)
12  await next()
13  console.log(5)
14})
15app.use(async function test3(ctx, next) {
16  await next()
17  // ctx.body = fs.createReadStream('asset/a.jpg')
18  console.log(4)
19})
20
21app.listen(8000)
22
23console.log('http://localhost:8000')
24