bfx-api-node-core/lib/ws2/subscribe.js

Core Bitfinex Node API

'use strict'

const debug = require('debug')('bfx:api:ws2:subscribe')
const send = require('./send')
const findSubscription = require('./find_subscription')

/**
 * Subscribes to the specified channel, buffers if the connection is not open.
 *
 * @param {Object} state
 * @param {string} channel - channel type, i.e. 'trades'
 * @param {Object} payload - channel filter, i.e. { symbol: '...' }
 * @returns {Object} state - original ref
 */
const subscribe = (state = {}, channel, payload = {}) => {
  debug('subscribing to %s: %j', channel, payload)

  const subscriptions = [...Object.values(state.channels), ...state.pendingSubscriptions]
  const existSubscription = findSubscription(subscriptions, { channel, ...payload })

  if (!existSubscription) {
    send(state, {
      ...payload,
      event: 'subscribe',
      channel
    })

    state.pendingSubscriptions.push({ channel, ...payload })
  }

  return state
}

module.exports = subscribe