Use the new Delta HMR implementation from the internal React Native CLI

Reviewed By: jeanlauliac

Differential Revision: D5765025

fbshipit-source-id: fbf516c26382773c623bd3e0c2ba8b668bfd8b31

Author: rafeca

local-cli/server/util/attachWebsocketServer.js

@@ -0,0 +1,72 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @format
+ * @flow
+ */
+
+'use strict';
+
+import type {Server as HTTPServer} from 'http';
+import type {Server as HTTPSServer} from 'https';
+
+type WebsocketServiceInterface<T> = {
+  +onClientConnect: (
+    url: string,
+    sendFn: (data: string) => mixed,
+  ) => Promise<T>,
+  +onClientDisconnect?: (client: T) => mixed,
+  +onClientError?: (client: T, e: Error) => mixed,
+  +onClientMessage?: (client: T, message: string) => mixed,
+};
+
+type HMROptions<TClient> = {
+  httpServer: HTTPServer | HTTPSServer,
+  websocketServer: WebsocketServiceInterface<TClient>,
+  path: string,
+};
+
+/**
+ * Attaches a WebSocket based connection to the Packager to expose
+ * Hot Module Replacement updates to the simulator.
+ */
+function attachWebsocketServer<TClient: Object>({
+  httpServer,
+  websocketServer,
+  path,
+}: HMROptions<TClient>) {
+  const WebSocketServer = require('ws').Server;
+  const wss = new WebSocketServer({
+    server: httpServer,
+    path: path,
+  });
+
+  wss.on('connection', async ws => {
+    const url = ws.upgradeReq.url;
+
+    const sendFn = ws.send.bind(ws);
+
+    const client = await websocketServer.onClientConnect(url, sendFn);
+
+    ws.on('error', e => {
+      websocketServer.onClientError && websocketServer.onClientError(client, e);
+    });
+
+    ws.on('close', () => {
+      websocketServer.onClientDisconnect &&
+        websocketServer.onClientDisconnect(client);
+    });
+
+    ws.on('message', message => {
+      websocketServer.onClientMessage &&
+        websocketServer.onClientMessage(client, message);
+    });
+  });
+}
+
+module.exports = attachWebsocketServer;