discord.js/src/client/websocket/WebSocketManager.js

const EventEmitter = require('events');
const { Events, Status } = require('../../util/Constants');
const WebSocketConnection = require('./WebSocketConnection');

/**
 * WebSocket Manager of the client.
 * @private
 */
class WebSocketManager extends EventEmitter {
  constructor(client) {
    super();
    /**
     * The client that instantiated this WebSocketManager
     * @type {Client}
     */
    this.client = client;

    /**
     * The WebSocket connection of this manager
     * @type {?WebSocketConnection}
     */
    this.connection = null;
  }

  /**
   * Sends a heartbeat on the available connection.
   * @returns {void}
   */
  heartbeat() {
    if (!this.connection) return this.debug('No connection to heartbeat');
    return this.connection.heartbeat();
  }

  /**
   * Emits a debug event.
   * @param {string} message Debug message
   * @returns {void}
   */
  debug(message) {
    return this.client.emit(Events.DEBUG, `[ws] ${message}`);
  }

  /**
   * Destroy the client.
   * @returns {void} Whether or not destruction was successful
   */
  destroy() {
    if (!this.connection) {
      this.debug('Attempted to destroy WebSocket but no connection exists!');
      return false;
    }
    return this.connection.destroy();
  }

  /**
   * Send a packet on the available WebSocket.
   * @param {Object} packet Packet to send
   * @returns {void}
   */
  send(packet) {
    if (!this.connection) {
      this.debug('No connection to websocket');
      return;
    }
    this.connection.send(packet);
  }

  /**
   * Connects the client to a gateway.
   * @param {string} gateway The gateway to connect to
   * @returns {boolean}
   */
  connect(gateway) {
    if (!this.connection) {
      this.connection = new WebSocketConnection(this, gateway);
      return true;
    }
    switch (this.connection.status) {
      case Status.IDLE:
      case Status.DISCONNECTED:
        this.connection.connect(gateway, 5500);
        return true;
      default:
        this.debug(`Couldn't connect to ${gateway} as the websocket is at state ${this.connection.status}`);
        return false;
    }
  }
}

module.exports = WebSocketManager;