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'

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])
    console.log(this.topics)
    this.opts = opts.connect || {}  // see options for new mqtt.Client
    // self bindings
    this.connect = this.connect.bind(this)
  }

  async connect () {

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

      // connect returns connected mqtt client instance so merge it to class
      // console.log(this)
      let mqtt = connect(this.url,this.opts)
      this._extend(mqtt,'subscribe,unsubscribe')
      this._log()
      this._listen()

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

      this.once('connect', () => {
        this.subscribe(this.topics)
        log.info('mqtt client connected to broker' )
        resolve(`mqtt client connected to broker at ${this._client.options.host}`)
      })

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

    }) //end promise

  }

  async subscribe(topic,options={}) {
    if (options.pub) {
      if (typeof topic==='string') topic = topic.split(',')
      this.topics=union(this.topics,topic)
    }
    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(topics,payload,options) {
    if (typeof topics !=='string'|| !Array.isArray(topics)) {
      payload = topics
      topics = this.topics
    }
    if (typeof topics ==='string') topics = topics.split(',')
    let serial = this._serialize(payload)
    if (serial) {
      let pubs = []
      topics.forEach( async topic => {
        pubs.push(this.publish(topic,serial,options))
      })
      return await Promise.all(pubs)

    }
  }

  registerPacketProcessor (func) {
    this._packetProcess = func
  }

  _serialize(json) {
    let [err,payload] = btc(JSON.stringify)(json)
    if (err) {  // await mqtt.unsubscribe('test2')
      // await mqtt.send({cmd:'test', status:'I\'m good'})
      // console.log('+++++++++++++++')
      log.warn(`error unable to stringify json:${json} - send aborted`)
      return null
    }
    return payload
  }

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

    async function messageProcess (topic,payload) {
      console.log('incoming messeage on topic', topic)
      let packet = this._handlePayload(payload)
      if (packet)  await this._packetProcess (packet,topic)

    }
  }

  _handlePayload (payload) {
    let [err,packet] = btc(JSON.parse)(payload.toString())
    if (err) {
      log.fatal({payload:payload},'Could not parse JSON of payload')
      console.log('Could not parse JSON of payload', payload.toString())
      return null
    }
    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('========================')
  // await mqtt.send({cmd:'test', status:'I\'m good'})
  // console.log('+++++++++++++++')=')
  }

  async _log() {

    const LOG_OPTS = {
      repo:'uci-mqtt',
      npm:'@uci/mqtt',
      file:'src/client.mjs',
      class:'Client',
      id:this.id,
      instance_created:new Date().getTime(),
      mqtt: this._client.options  // await mqtt.unsubscribe('test2')
      // await mqtt.send({cmd:'test', status:'I\'m good'})
      // console.log('+++++++++++++++')
    }

    log = logger.child(LOG_OPTS)

    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