ws.js

'use strict'

const {EventEmitter} = require('events')
const debug = require('debug')('bitfinex:ws')
const crypto = require('crypto')
const WebSocket = require('ws')
const util = require('util')

/**
 * Handles communitaction with Bitfinex WebSocket API.
 * @param {sting} APIKey
 * @param {string} APISecret
 * @event
 * @class
 */
const BitfinexWS = function (APIKey, APISecret) {
  EventEmitter.call(this)

  this.APIKey = APIKey
  this.APISecret = APISecret
  this.ws = new WebSocket(BitfinexWS.WebSocketURI)
    /**
     * @event BitfinexWS#message
     * @type {object}
     */
  this.ws.on('message', this.onMessage.bind(this))
    /**
     * WebSocket connection is open. Ready to send.
     * @event BitfinexWS#open
     */
  this.ws.on('open', this.onOpen.bind(this))
    /**
     * @event BitfinexWS#error
     */
  this.ws.on('error', this.onError.bind(this))
    /**
     * WebSocket connection is closed.
     * @event BitfinexWS#close
     */
  this.ws.on('close', this.onClose.bind(this))
}

util.inherits(BitfinexWS, EventEmitter)

/**
 * @constant
 * @type {String}
 */
BitfinexWS.WebSocketURI = 'wss://api.bitfinex.com/ws/'

BitfinexWS.prototype.onMessage = function (msg, flags) {
  msg = JSON.parse(msg)
  debug('Received message: %j', msg)
  debug('Emmited message event')
  this.emit('message', msg, flags)

  if (!Array.isArray(msg) && msg.event) {
    if (msg.event === 'subscribed') {
      debug('Subscription report received')
            // Inform the user the new event name that will be triggered
      const data = {
        channel: msg.channel,
        chanId: msg.chanId,
        pair: msg.pair
      }
            // Save to event map
      this.channelMap[msg.chanId] = data
      debug('Emitting \'subscribed\' %j', data)
            /**
             * @event BitfinexWS#subscribed
             * @type {object}
             * @property {string} channel - Channel type
             * @property {string} pair - Currency pair.
             * @property {number} chanId - Channel ID sended by Bitfinex
             */
      this.emit('subscribed', data)
    } else if (msg.event === 'auth' && msg.status !== 'OK') {
      this.emit('error', msg)
      debug('Emitting \'error\' %j', msg)
    } else if (msg.event === 'auth') {
      this.channelMap[msg.chanId] = {
        channel: 'auth'
      }
      debug('Emitting \'%s\' %j', msg.event, msg)
            /**
             * @event BitfinexWS#auth
             */
      this.emit(msg.event, msg)
    } else {
      debug('Emitting \'%s\' %j', msg.event, msg)
      this.emit(msg.event, msg)
    }
  } else {
    debug('Received data from a channel')
        // First element of Array is the channelId, the rest is the info.
    const channelId = msg.shift() // Pop the first element
    const event = this.channelMap[channelId]
    if (event) {
      debug('Message in \'%s\' channel', event.channel)
      if (event.channel === 'book') {
        this._processBookEvent(msg, event)
      } else if (event.channel === 'trades') {
        this._processTradeEvent(msg, event)
      } else if (event.channel === 'ticker') {
        this._processTickerEvent(msg, event)
      } else if (event.channel === 'auth') {
        this._processUserEvent(msg)
      } else {
        debug('Message in unknown channel')
      }
    }
  }
}

BitfinexWS.prototype._processUserEvent = function (msg) {
  if (msg[0] === 'hb') { // HeatBeart
    debug('Received HeatBeart in user channel')
  } else {
    const event = msg[0]
    const data = msg[1]
    if (Array.isArray(data[0])) {
      data[0].forEach((ele) => {
        debug('Emitting \'%s\' %j', event, ele)
        this.emit(event, ele)
      })
    } else if (data.length) {
      debug('Emitting \'%s\', %j', event, data)
            /**
             * position snapshot
             * @event BitfinexWS#ps
             */
            /**
             * new position
             * @event BitfinexWS#pn
             */
            /**
             * position update
             * @event BitfinexWS#pu
             */
            /**
             * position close
             * @event BitfinexWS#pc
             */
            /**
             * wallet snapshot
             * @event BitfinexWS#ws
             */
            /**
             * wallet snapshot
             * @event BitfinexWS#ws
             */
            /**
             * order snapshot
             * @event BitfinexWS#os
             */
            /**
             * new order
             * @event BitfinexWS#on
             */
            /**
             * order update
             * @event BitfinexWS#ou
             */
            /**
             * order cancel
             * @event BitfinexWS#oc
             */
            /**
             * trade executed
             * @event BitfinexWS#te
             */
            /**
             * trade execution update
             * @event BitfinexWS#tu
             */
            // TODO: send Object with key: values
      this.emit(event, data)
    }
  }
}

BitfinexWS.prototype._processTickerEvent = function (msg, event) {
  if (msg[0] === 'hb') { // HeatBeart
    debug('Received HeatBeart in %s ticker channel', event.pair)
  } else if (msg.length > 9) { // Update
    const update = {
      bid: msg[0],
      bidSize: msg[1],
      ask: msg[2],
      askSize: msg[3],
      dailyChange: msg[4],
      dailyChangePerc: msg[5],
      lastPrice: msg[6],
      volume: msg[7],
      high: msg[8],
      low: msg[9]
    }
    debug('Emitting ticker, %s, %j', event.pair, update)
        /**
         * @event BitfinexWS#ticker
         * @type {string}
         * @type {object}
         * @property {number} bid
         * @property {number} bidSize
         * @property {number} ask
         * @property {number} askSize
         * @property {number} dailyChange
         * @property {number} dailyChangePerc
         * @property {number} lastPrice
         * @property {number} volume
         * @property {number} high
         * @property {number} low
         */
    this.emit('ticker', event.pair, update)
  }
}

BitfinexWS.prototype._processTradeEvent = function (msg, event) {
    // Snapshot
  if (Array.isArray(msg[0])) {
    msg[0].forEach((update) => {
      update = {
        seq: update[0],
        timestamp: update[1],
        price: update[2],
        amount: update[3]
      }
      debug('Emitting trade, %s, %j', event.pair, update)
      this.emit('trade', event.pair, update)
    })
  } else if (msg[0] === 'hb') { // HeatBeart
    debug('Received HeatBeart in %s trade channel', event.pair)
  } else if (msg[0] === 'te') { // Trade executed
    const update = {
      seq: msg[1],
      timestamp: msg[2],
      price: msg[3],
      amount: msg[4]
    }
    debug('Emitting trade, %s, %j', event.pair, update)
        /**
         * @event BitfinexWS#trade
         * @type {string}
         * @type {object}
         * @property {string} seq
         * @property {number} timestamp
         * @property {number} price
         * @property {number} amount
         * @see http://docs.bitfinex.com/#trades75
         */
    this.emit('trade', event.pair, update)
  } else if (msg[0] === 'tu') { // Trade executed
    const update = {
      seq: msg[1],
      id: msg[2],
      timestamp: msg[3],
      price: msg[4],
      amount: msg[5]
    }
    debug('Emitting trade, %s, %j', event.pair, update)
        /**
         * @event BitfinexWS#trade
         * @type {string}
         * @type {object}
         * @property {string} seq
         * @property {number} id
         * @property {number} timestamp
         * @property {number} price
         * @property {number} amount
         * @see http://docs.bitfinex.com/#trades75
         */
    this.emit('trade', event.pair, update)
  }
}

BitfinexWS.prototype._processBookEvent = function (msg, event) {
    // Snapshot
  if (Array.isArray(msg[0])) {
    msg[0].forEach((update) => {
      update = {
        price: update[0],
        count: update[1],
        amount: update[2]
      }
      debug('Emitting orderbook, %s, %j', event.pair, update)
      this.emit('orderbook', event.pair, update)
    })
  } else if (msg[0] === 'hb') { // HeatBeart
    debug('Received HeatBeart in %s book channel', event.pair)
  } else if (msg.length > 2) { // Update
    const update = {
      price: msg[0],
      count: msg[1],
      amount: msg[2]
    }
    debug('Emitting orderbook, %s, %j', event.pair, update)
        /**
         * @event BitfinexWS#orderbook
         * @type {string}
         * @type {object}
         * @property {string} price
         * @property {number} count
         * @property {number} amount
         * @see http://docs.bitfinex.com/#order-books
         */
    this.emit('orderbook', event.pair, update)
  }
}

BitfinexWS.prototype.close = function () {
  this.ws.close()
}

BitfinexWS.prototype.onOpen = function () {
  this.channelMap = {} // Map channels IDs to events
  this.emit('open')
}

BitfinexWS.prototype.onError = function (error) {
  this.emit('error', error)
}

BitfinexWS.prototype.onClose = function () {
  this.emit('close')
}

BitfinexWS.prototype.send = function (msg) {
  debug('Sending %j', msg)
  this.ws.send(JSON.stringify(msg))
}

/**
 * Subscribe to Order book updates. Snapshot will be sended as multiple updates.
 * Event will be emited as `PAIRNAME_book`.
 * @param  {string} [pair]      BTCUSD, LTCUSD or LTCBTC. Default BTCUSD
 * @param  {string} [precision] Level of price aggregation (P0, P1, P2, P3).
 *                              The default is P0.
 * @param  {string} [length]    Number of price points. 25 (default) or 100.
 * @see http://docs.bitfinex.com/#order-books
 */
BitfinexWS.prototype.subscribeOrderBook =
    function (pair = 'BTCUSD', precision = 'P0', length = '25') {
      this.send({
        event: 'subscribe',
        channel: 'book',
        pair,
        prec: precision,
        len: length
      })
    }

/**
 * Subscribe to trades. Snapshot will be sended as multiple updates.
 * Event will be emited as `PAIRNAME_trades`.
 * @param  {string} [pair]      BTCUSD, LTCUSD or LTCBTC. Default BTCUSD
 * @see http://docs.bitfinex.com/#trades75
 */
BitfinexWS.prototype.subscribeTrades = function (pair = 'BTCUSD') {
  this.send({
    event: 'subscribe',
    channel: 'trades',
    pair
  })
}

/**
 * Subscribe to ticker updates. The ticker is a high level overview of the state
 * of the market. It shows you the current best bid and ask, as well as the last
 * trade price.
 *
 * Event will be emited as `PAIRNAME_ticker`.
 * @param  {string} [pair]      BTCUSD, LTCUSD or LTCBTC. Default BTCUSD
 * @see http://docs.bitfinex.com/#ticker76
 */
BitfinexWS.prototype.subscribeTicker = function (pair = 'BTCUSD') {
  this.send({
    event: 'subscribe',
    channel: 'ticker',
    pair
  })
}

/**
 * Unsubscribe to a channel.
 * @param  {number} chanId ID of the channel received on `subscribed` event.
 */
BitfinexWS.prototype.unsubscribe = function (chanId) {
  this.send({
    event: 'unsubscribe',
    chanId
  })
}

/**
 * Autenticate the user. Will receive executed traded updates.
 * @see http://docs.bitfinex.com/#wallet-updates
 */
BitfinexWS.prototype.auth = function () {
  const payload = 'AUTH' + (new Date().getTime())
  const signature = crypto.createHmac('sha384', this.APISecret)
    .update(payload)
    .digest('hex')
  this.send({
    event: 'auth',
    apiKey: this.APIKey,
    authSig: signature,
    authPayload: payload
  })
}

module.exports = BitfinexWS