pubsubr/lib/client.js

pub and sub to loopback components

const connect = require('./connect');
const utils = require('./utils');
const _ = require('lodash');
const request = require('./request');

module.exports = exports = Client;

function Client(options, apiUrl) {
  this.options = options;
  this.apiUrl = apiUrl;
  this.connect = connect(options);
  this.map = {};
  this.times = {};
  this.connect.on('message', (topic, message) => {
    const payload = utils.decodeTopic(topic);
    try {
      message = JSON.parse(message);
    } catch (err) {}
    payload.message = message;
    const keys = utils.getMapTopic(topic, this.map);
    keys.forEach((item) => {
      // record the topic last time
      this.times[item] = new Date();
      this.map[item](null, payload);
    })
  });

  this.connect.on('reconnect', () => {
    if (this.apiUrl) {
      const timesKeys = Object.keys(this.times);
      timesKeys.forEach((item) => {
        let where = utils.decodeTopic(item);
        const keys = Object.keys(where);
        keys.forEach((key) => {
          if (where[key] === '+' || where[key] === '#') {
            delete where[key];
          }
        });
        where = _.assign(where, {updatedAt: {gt: this.times[item]}});
        this.map[item] && request.reassembly(this.apiUrl, where, this.map[item]);
      })
    }
  });
}

/**
 * Subscribe to a topic or topics
 * @param topic topic is a String topic to subscribe to or an Array of topics to subscribe to. It can also be an object,
 * it has as object keys the topic name and as value the QoS, like {'test1': 0, 'test2': 1}.
 * MQTT topic wildcard characters are supported (+ - for single level and # - for multi level)
 * @param opts is the options to subscribe with, including:
 *  * qos qos subscription level, default 0
 * @param handler
 */
Client.prototype.subscribe = function (topic, opts, handler) {
  if (typeof handler === 'undefined' && typeof opts === 'function') {
    handler = opts;
    opts = {};
  }
  if (opts.time && (new Date(opts.time) instanceof Date) && this.apiUrl) {
    let where = utils.decodeTopic(topic);
    const keys = Object.keys(where);
    keys.forEach((key) => {
      if (where[key] === '+' || where[key] === '#') {
        delete where[key];
      }
    });
    where = _.assign(where, {updatedAt: {gt: opts.time}});
    request.reassembly(this.apiUrl, where, handler);
  }
  this.connect.subscribe(topic, _.pick(opts, ['qos']));
  this.map[topic] = handler;
};

/**
 * Unsubscribe from a topic or topics
 * @param topic is a String topic or an array of topics to unsubscribe from
 * @param cb  - function (err), fired on unsuback. An error occurs if client is disconnecting.
 */
Client.prototype.unsubscribe = function (topic, cb) {
  this.connect.unsubscribe(topic, cb);
  delete this.map['topic'];
};