uci-websocket-client/src/WSConsumer.js

// Websocket is a native global for vanilla JS
// /* globals WebSocket:true */

import btc from 'better-try-catch'
import EventEmitter from 'eventemitter3'
import autoBind from 'auto-bind'
import WS from 'reconnecting-websocket'

/**
 * Web Socket Consumer - An in browser consumer/client that can communicate via UCI packets
 * extends {@link https://github.com/primus/eventemitter3 event emitter 3} an in browser event emitter
 * uses the browser built in vanilla js global {@link https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/WebSocket Websocket client class}
 * @extends EventEmitter
 */
class WSConsumer extends EventEmitter {
  /**
   * constructor - Description
   *
   * @param {type}   url  URL of UCI websocket server
   *
   */
  constructor (url, opts = {}) {
    super()
    this.name = opts.name || 'browser'
    this.instanceID = new Date().getTime()
    this.url = url
    this.wsopts = opts.ws || { maxReconnectionDelay: 10000,minReconnectionDelay: 1000 + Math.random() * 4000,reconnectionDelayGrowFactor: 1.3,minUptime: 5000,connectionTimeout: 4000,maxRetries: Infinity,debug: false,}
    this.protocol = opts.protocol // available if needed but not documented
    this.socket = {}
    autoBind(this)
  }

  /**
   * connect - After instantiating this must be called to connect to a UCI WesbSocket Sever
   * @required
   * as coded will reconnect  and set up listeners again if the socket gets closed
   * commented code work
   * but opted to use https://www.npmjs.com/package/reconnecting-websocket
   */

  // async connect () {
  //   return new Promise((resolve, reject) => {
  //     const init = (socket) => {
  //       if (socket) console.error('Disconnected from Server')
  //       this.socket = new WebSocket(this.url, this.protocol)
  //       this.socket.addEventListener('close', init)
  //       this.socket.addEventListener('open', open.bind(this))
  //     }
  //
  //     setTimeout(function () {
  //       reject(new Error('Socket did not initially connect in 20 seconds'))
  //     }, 20000)
  //
  //     init()
  //
  //     function open () {
  //       this.listen()
  //       resolve(`socket open to server at : ${this.url}`)
  //     }
  //   })
  // }

  async connect () {
    return new Promise((resolve, reject) => {
      this.socket = new WS(this.url, this.protocol, this.wsopts)
      this.socket.onopen = open.bind(this)

      setTimeout(function () {
        reject(new Error('Socket did not initially connect in 20 seconds'))
      }, 20000)
      // this.socket.onerror = (ev) => { reject(`could not connect/reconnect to server : ${ev}`)}

      function open () {
        this.listen()
        resolve(`socket open to server at : ${this.url}`)
      }

    })
  }

  /**
   * listen - Description
   *
   * @param {type} func Description
   *
   * @returns {type} Description
   */
  listen (func) {
    this.socket.addEventListener('message', handler.bind(this))
    this.on('pushed', async function (packet) {
      // TODO do some extra security here for 'evil' pushed packets
      let res = await this._packetProcess(packet)
      if (!res) {
        // if process was not promise returning like just logged to console
        console.log(
          'warning: consumer process function was not promise returning'
        )
      }
    })

    function handler (event) {
      let packet = {}
      if (this.socket.readyState === 1) {
        let [err, parsed] = btc(JSON.parse)(event.data)
        if (err) packet = { error: `Could not parse JSON: ${event.data}` }
        else packet = parsed
      } else {
        packet = {
          error: `Connection not Ready, CODE:${this.socket.readyState}`
        }
      }
      // console.log('in the handler', event.data)
      if (func) func(packet)
      this.emit(packet._header.id, packet)
    }
  }

  /**
   * send - Description
   *
   * @param {type} packet Description
   *
   * @returns {type} Description
   */
  async send (packet) {
    return new Promise((resolve, reject) => {
      if (this.socket.readyState !== 1)
        reject(
          new Error(`Connection not Ready, CODE:${this.socket.readyState}`)
        )
      packet._header = {
        id: Math.random()
          .toString()
          .slice(2), // need this for when multiple sends for different consumers use same packet instanceack
        sender: { name: this.name, instanceID: this.instanceID },
        url: this.url
      }
      let [err, message] = btc(JSON.stringify)(packet)
      if (err) reject(new Error(`Could not JSON stringify: ${packet}`))
      // console.log('message to send', message)
      this.socket.send(message)
      // listen for when packet comes back with unique header id
      this.once(packet._header.id, async function (reply) {
        let res = await this._packetProcess(reply)
        if (!res) {
          // if process was not promise returning like just logged to console
          res = reply
          console.log(
            'consumer function was not promise returning - resolving unprocessed'
          )
        }
        resolve(res)
      }) // end reply listener
    })
  }

  /**
   * registerPacketProcessor - attaches the passed packet function as the one to process incoming packets
   *  the funcion must take a uci packet object and return a promise whose resolution should be a uci packet if further communication is desir
   *
   * @param {function} func function to do the incoming packet processing
   *
   */
  registerPacketProcessor (func) {
    this._packetProcess = func
  }

  async _packetProcess (packet) {
    return Promise.resolve(packet)
  }
} // end Consumer Class

export default WSConsumer