uci-mqtt/src/client.js

import { connect } from 'async-mqtt'
import merge from 'lodash.merge'
import btc from 'better-try-catch'
import union from 'lodash.union'
import xor from 'lodash.xor'
import logger from '@uci/logger'
import isPlainObject from 'is-plain-object'

let log = {}

export default class Client {
  constructor (opts={}) {
    this.id = opts.id || opts.name || 'mqtt:'+ new Date().getTime()
    this.url = opts.url || ''
    // subscription topics can be string of commna delimited or array of strings see object see mqtt.js docs
    this.topics = Array.isArray(opts.topics) ? opts.topics : (opts.topics ? opts.topics.split(',') : [this.id])
    this.opts = opts.connect || {}  // see options for new mqtt.Client
    // self bindings
    this.connect = this.connect.bind(this)
    this.push = this.send
  }

  async connect () {

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

      let mqtt = connect(this.url,this.opts)
      this._extend(mqtt,'subscribe,unsubscribe')  // merge mqtt client into class extend with given functions
      let timeout = this.opts.connectTimeout || 5000
      setTimeout(()=>{
        reject(`ending mqtt connection attempt, no broker at ${this._client.options.hostname}:${this._client.options.port}`)
      },timeout)

      this.once('connect', () => {
        this._log()
        this._listen()

        this.on('reconnect', () => {
          log.info('mqtt client reconnected to broker' )
          this.subscribe(this.topics)
        })

        this.on('error', err => {
          log.fatal({err:err},'connection error to broker' )
          console.log('connection error',err.code)
        })

        this.subscribe(this.topics)
        log.info({options:this._client.options},`mqtt client connected to broker at ${this._client.options.hostname}:${this._client.options.port}`)
        resolve(`mqtt client connected to broker at ${this._client.options.hostname}:${this._client.options.port}`)
      })

    }) //end promise
  }

  async subscribe(topic,options={}) {
    if (options.pub) {
      if (typeof topic==='string') topic = topic.split(',')
      this.topics=union(this.topics,topic)
    }
    log.info(`subscription for topic ${topic} added`)
    this._subscribe(topic,options)
  }

  async unsubscribe(topic,options={}) {
    if (!options.pub) {
      if (typeof topic==='string') topic = topic.split(',')
      this.topics=xor(this.topics,topic)
    }
    this._unsubscribe(topic)
  }

  async send(packet,topics,options) {
    if (typeof topics !=='string' && !Array.isArray(topics)) {
      options = topics
      topics = this.topics
    } else { if (typeof topics ==='string') topics=topics.split(',') }
    let payload = {}
    if (typeof packet !== 'string') {
      payload = this._serialize(packet)
      if (!payload) payload = this._serialize({ err: 'could not serialze packet'})
      topics = [packet.cmd] || topics // if payload has a cmd use that as topic
    }
    else payload = this._serialize({ data:packet })
    let pubs = []
    topics.forEach( async topic => {
      log.info(`sending ${payload} to topic ${topic} with options ${options}`)
      pubs.push(this.publish(topic,payload,options))
    })
    return await Promise.all(pubs)
  }

  registerPacketProcessor (func) {
    this._packetProcess = func
  }

  _serialize(json) {
    let [err,payload] = btc(JSON.stringify)(json)
    if (err) {
      log.warn(`error unable to stringify json:${json}`)
      return null
    }
    return payload
  }

  _listen () {
    log.info(`listening for incoming packets from broker on topics ${this.topics}`)
    this.on('message',messageProcess.bind(this))

    async function messageProcess (topic,payload) {
      log.info('incoming message on topic', topic)
      let packet = this._handlePayload(payload)
      if(packet) packet.cmd = packet.cmd || topic  // payload had no command that use topic as cmd
      else packet = {cmd:topic}
      let res = await this._packetProcess(packet,topic) || {}
      this.send(res)
    }
  }

  _handlePayload (payload) {
    let [err,packet] = btc(JSON.parse)(payload.toString())
    if (err) {
      log.info('payload not json returning as prop data:<payload>')
    }
    if (!isPlainObject(packet))  packet = { data:payload.toString() }
    return packet
  }

  // default packet process just a simple console logger.  ignores any cmd: prop
  _packetProcess (packet,topic) {
    console.log('=========================')
    console.log('default consumer processor\npacket from broker on topic:',topic)
    console.dir(packet)
    console.log(packet.status)
    console.log('========================')
  }

  async _log() {

    log = logger({file:'src/client.js',class:'Client',name:'mqtt',id:this.id})

    this.on('close', () => {
      log.info('connection to broker was closed')
    })

    this.on('offline', () => {
      log.info('this client has gone offline from broker')
    })

    this.on('packetsend', packet => {
      log.info({packet:packet},'outgoing packet to mqtt broker')
    })

    this.on('packetreceive', packet => {
      log.info({packet:packet},'incoming packet from mqtt broker')
    })

  }

  _extend (obj, funcs) {
    let temp = {}
    funcs = funcs.split(',')
    funcs.forEach(func => {
      temp[func] = this[func]
    })
    merge(this,obj)
    funcs.forEach(func => {
      this['_'+func]=this[func]
      this[func] = temp[func]
    })
  }

}  // end mqtt client class