Add dynamic routes to Fastify

dynamic-route.js

// a quick check to implement a dynamic route plugin for fastify

const { fastify } = require('fastify')
const fp = require('fastify-plugin')
const http = require('http')

const EventEmitter = require('events')

main()
async function main () {
  let app = fastify()

  app.register(fp(async function plugin (instance, opts) {
    const ee = new EventEmitter()
    ee.on('replace', opts.rootInstanceReplacer)

    instance.decorate('dynamicPost', async function () {
      const replace = fastify(instance.initialConfig)
      // todo get all the plugins/addSchema/addHook from the original instance

      // how to preserve the encapsulation?
      replace.post(...arguments)

      await replace.ready()

      app.server.removeListener('request', app.routing)

      replace.server = app.server
      replace.server.on('request', replace.routing)

      // todo app.dispose()
      // - close connections or copy the children?
      // - fastify builder application or clone the children?
      // - adds a new recreate method to the fastify instance?

      ee.emit('replace', replace)

      return replace
    })
  }), {
    rootInstanceReplacer: (newFastify) => { app = newFastify }
  })

  app.get('/', async (request, reply) => {
    console.log('GET /')
    await app.dynamicPost('/', () => {
      console.log('post')
      return { hello: 'world' }
    })
    return ''
  })

  console.log('listening')
  // await app.listen(8080)
  // { const res = await httpCall('http://localhost:8080/', 'GET')
  //   console.log(res.statusCode)
  // }
  // { const res = await httpCall('http://localhost:8080/', 'POST')
  //   console.log(res.statusCode) }
  // await app.close()

  await app.ready()
  { const res = await app.inject('/')
    console.log(res.statusCode)
  }
  { const res = await app.inject({ method: 'POST', url: '/' })
    console.log(res.statusCode) }
}

function httpCall (url, method, body) {
  return new Promise((resolve, reject) => {
    const req = http.request(url, { method }, res => {
      let data = ''
      res.on('data', chunk => { data += chunk })
      res.on('end', () => {
        resolve({ statusCode: res.statusCode, data })
      })
    })
    req.on('error', reject)
    req.end(body)
  })
}