uci-socket/src/consumer.mjs

import { Socket } from 'net'
import btc from 'better-try-catch'
import JsonStream from './json-stream'
import {promisify} from 'util'

import logger from '../../uci-logger/src/logger'
let log = {}
const LOG_OPTS = {
  repo:'uci-socket',
  npm:'@uci/socket',
  file:'src/consumer.mjs',
  class:'Consumer',
  id:this.id,
  instance_created:new Date().getTime()
}

const DEFAULT_PIPE = (process.env.SOCKETS_DIR || __dirname) + '/uci-socket.sock'

export default class Consumer extends Socket {
  constructor (opts={}) {
    super()
    this.id = opts.id || opts.name || 'socket:'+ new Date().getTime()
    if (!opts.path && opts.np) opts.path = DEFAULT_PIPE
    if (!opts.path) {
      opts.host = opts.host || '127.0.0.1'
      opts.port = opts.port || 8080
    } else opts.np = true
    this.opts=opts
    this.keepAlive = opts.keepAlive ? opts.keepAlive : true
    this._ready = false
    this.timeout = opts.timeout || 500
    this.wait = opts.wait || 5
    this.stream = new JsonStream()
    log = logger.child(LOG_OPTS)
    // bind to class for other class functions
    this.connect = this.connect.bind(this)
    this.__ready = this.__ready.bind(this)
    // this._write = this._write.bind(this)
  }

  async connect () {

    // if (context) this.packet.context = context
    // else this.packet.context = this

    return new Promise( (resolve,reject) => {

      const connect = () => {
        if (this.opts.host ==='127.0.0.1') log.warn('tcp consumer on same machine as host, use named Pipe(Unix) Socket Instead')
        log.info({opts:this.opts},`attempting to connect ${this.id} to socket`)
        super.connect(this.opts)
      }

      const timeout = setTimeout(() =>{
        reject({opts:this.opts},`unable to connect in ${this.timeout*10}ms`)
      }
        ,this.timeout*10)

      this.once('connect', async () => {
        clearTimeout(timeout)
        this._listen()
        log.info({opts:this.opts},'connected waiting for socket ready handshake')
        this.setKeepAlive(this.keepAlive,100)
        let [err, res] = await btc(isReady).bind(this)(this.__ready, this.wait, this.timeout)
        if (err) reject(err)
        log.info('handshake done, authenticating')
        // TODO authenticate here by encrypting a payload with private key and sending that.
        // await btc(authenticate)
        resolve(res)
      })

      this.on('error', async (err) => {
        if (err.code === 'EISCONN') {
          return resolve('ready')
        }
        log.warn(err.code)
        setTimeout(() =>{
          // log.warn(`retrying connect to ${this.opts}`)
          connect()
        }
          ,this.wait*100)
      })

      connect()

    }) //end promise

  }


  async send(packet) {
    return new Promise( async (resolve) => {
      setTimeout(() => {resolve({error:'no response from socket in 10sec'})},10000)
      packet._id = Math.random().toString().slice(2)
      // console.log('sending to socket', packet.id)
      let [err, res] = await btc(this.stream.serialize)(packet)
      if (err) resolve({error:'unable to serialize packet for sending', packet:packet})
      log.info(await this.__write(res))
      this.once(packet._id,async function(reply){
        // console.log('reply emitted',reply)
        this.removeAllListeners(reply.id)
        delete reply._id
        let res = await this._packetProcess(reply)
        if (!res) {   // if process was not promise returning like just logged to console
          res = reply
          log.warn('consumer function was not promise returning - resolving unprocessed')
        } 
        resolve(res)
      }) //end listener
    })
  }

  // TODO register alt stream processor (emit 'message' with JSON, serialize function, onData method for raw socket chucks)
  // TODO register authenciation function (set up default)

  registerPacketProcessor (func) {
    this._packetProcess = func
  }

  // PRIVATE METHODS

  async __write(packet) {
    // timeout already set if sockect can't be drained in 10 secs
    return new Promise(resolve => {
      const cb = () => resolve('packet written to socket stream')
      if (!super.write(packet)) {
        this.once('drain',cb )
      } else {
        process.nextTick(cb)
      }

    })
  }

  __ready() {return this._ready}

  async _listen () {
    log.info('listening for incoming packets from socket')
    this.on('data', this.stream.onData)
    this.stream.on('message', messageProcess.bind(this))
    async function messageProcess (packet) {
      if (packet._handshake) {
        this._ready = true
        return }
      // TODO send back ack with consumer ID and authorization and wait
      // when authorized drop through here to emit
      // console.log('incoming packet',packet)
      this.emit(packet._id, packet)
    }
  }

  // default packet process just a simple console logger.  ignores any cmd: prop
  _packetProcess (packet) {
    console.log('default consumer processor -- log packet from socket to console')
    console.dir(packet)
  }

}  // end class


// HELP FUNCTIONS
// wait until a passed ready function returns true
function isReady(ready, wait=30, timeout=1000) {
  let time = 0
  return new Promise((resolve, reject) => {
    (function waitReady(){
      if (time > timeout) return reject(`timeout waiting for socket ready handshake - ${timeout}ms`)
      if (ready()) return resolve('ready')
      log.info(`waiting ${wait}ms for handshake`)
      time += wait
      setTimeout(waitReady, wait)
    })()
  })
}