websocket cleanup (#1346)

* websocket cleanup

* resume event

* Update Resumed.js

* Update WebSocketManager.js

src/client/websocket/WebSocketConnection.js

@@ -0,0 +1,105 @@
+const browser = require('os').platform() === 'browser';
+const EventEmitter = require('events');
+const zlib = require('zlib');
+const erlpack = (function findErlpack() {
+  try {
+    const e = require('erlpack');
+    if (!e.pack) return null;
+    return e;
+  } catch (e) {
+    return null;
+  }
+}());
+
+const WebSocket = (function findWebSocket() {
+  if (browser) return window.WebSocket; // eslint-disable-line no-undef
+  try {
+    return require('uws');
+  } catch (e) {
+    return require('ws');
+  }
+}());
+
+/**
+ * Abstracts a WebSocket connection with decoding/encoding for the discord gateway
+ * @private
+ */
+class WebSocketConnection extends WebSocket {
+  /**
+   * @param {string} gateway Websocket gateway to connect to
+   */
+  constructor(gateway) {
+    super(gateway);
+    this.e = new EventEmitter();
+    if (browser) this.binaryType = 'arraybuffer';
+    this.onmessage = this.eventMessage.bind(this);
+    this.onopen = this.e.emit.bind(this.e, 'open');
+    this.onclose = this.e.emit.bind(this.e, 'close');
+    this.onerror = this.e.emit.bind(this.e, 'error');
+  }
+
+  /**
+   * Called when the websocket gets a message
+   * @param {Object} event Close event object
+   * @returns {Promise<boolean>}
+   */
+  eventMessage(event) {
+    try {
+      const data = this.unpack(event.data);
+      this.e.emit('packet', data);
+      return true;
+    } catch (err) {
+      if (this.e.listenerCount('decodeError')) this.e.emit('decodeError', err);
+      return false;
+    }
+  }
+
+  /**
+   * Send data over the websocket
+   * @param {string|Buffer} data Data to send
+   */
+  send(data) {
+    super.send(this.pack(data));
+  }
+
+  /**
+   * Pack data using JSON or Erlpack
+   * @param {*} data Data to pack
+   * @returns {string|Buffer}
+   */
+  pack(data) {
+    return erlpack ? erlpack.pack(data) : JSON.stringify(data);
+  }
+
+  /**
+   * Unpack data using JSON or Erlpack
+   * @param {string|ArrayBuffer|Buffer} data Data to unpack
+   * @returns {string|Object}
+   */
+  unpack(data) {
+    if (erlpack && typeof data !== 'string') {
+      if (data instanceof ArrayBuffer) data = Buffer.from(new Uint8Array(data));
+      return erlpack.unpack(data);
+    } else {
+      if (data instanceof ArrayBuffer || data instanceof Buffer) data = this.inflate(data);
+      return JSON.parse(data);
+    }
+  }
+
+  /**
+   * Zlib inflate data
+   * @param {string|Buffer} data Data to inflate
+   * @returns {string|Buffer}
+   */
+  inflate(data) {
+    return erlpack ? data : zlib.inflateSync(data).toString();
+  }
+}
+
+/**
+ * Encoding the WebSocket connections will use
+ * @type {string}
+ */
+WebSocketConnection.ENCODING = erlpack ? 'etf' : 'json';
+
+module.exports = WebSocketConnection;