Optionally forward status updates from bridge to extension

IMPLEMENTATION.md

@@ -46,7 +46,7 @@ Cast SDK API calls are translated into Chromecast protocol messages and sent via
 | No. | Subject                                       | Origin     | Destination | Description |
 | --: | --------------------------------------------- | ---------- | ----------- | ----------- |
 |  1  | `shim:/initialized`                           | background | shim        | Sent once bridge has been created. |
-|  2  | `bridge:/startDiscovery`                      | shim       | bridge      | Starts network discovery. |
+|  2  | `bridge:/initialize`                          | shim       | bridge      | Starts network discovery. |
 |  3  | `shim:/serviceUp`                             | bridge     | shim        | Sent once a receiver device has been found. |
 |  4  | `shim:/serviceDown`                           | bridge     | shim        | Sent once a receiver device has been lost. |
 |  5  | `main:/openPopup`                             | shim       | background  | Opens the receiver selection popup. |

app/src/main.ts

@@ -10,12 +10,19 @@ import Media from "./Media";
 import Session from "./Session";
 import * as transforms from "./transforms";
 
+import { Channel, Client } from "castv2";
+
 import { Message } from "./types";
 
 import { __applicationName
        , __applicationVersion } from "../package.json";
 
 
+const NS_CONNECTION = "urn:x-cast:com.google.cast.tp.connection";
+const NS_HEARTBEAT = "urn:x-cast:com.google.cast.tp.heartbeat";
+const NS_RECEIVER = "urn:x-cast:com.google.cast.receiver";
+
+
 // Increase listener limit
 events.EventEmitter.defaultMaxListeners = 50;
 
@@ -50,6 +57,10 @@ function sendMessage (message: object) {
 }
 
 
+interface InitializeOptions {
+    shouldWatchStatus?: boolean;
+}
+
 // Existing counterpart Media/Session objects
 const existingSessions: Map<string, Session> = new Map();
 const existingMedia: Map<string, Media> = new Map();
@@ -111,11 +122,14 @@ async function handleMessage (message: Message) {
             return __applicationVersion;
         }
 
-        case "bridge:/startDiscovery": {
-            browser.start();
+        case "bridge:/initialize": {
+            const options: InitializeOptions = message.data;
+            initialize(options);
+
             break;
         }
 
+
         case "bridge:/startHttpServer": {
             const { filePath, port } = message.data;
 
@@ -173,25 +187,128 @@ async function handleMessage (message: Message) {
     }
 }
 
+function initialize (options: InitializeOptions) {
+    browser.on("serviceUp", (service: dnssd.Service) => {
+        const address = service.addresses[0];
+        const port = service.port;
+        const id = service.txt.id;
 
-browser.on("serviceUp", (service: dnssd.Service) => {
-    transforms.encode.write({
-        subject: "shim:/serviceUp"
-      , data: {
-            address: service.addresses[0]
-          , port: service.port
-          , id: service.txt.id
-          , friendlyName: service.txt.fn
-          , currentApp: service.txt.rs
+        if (options.shouldWatchStatus) {
+            registerStatusListener(address, port, id);
         }
-    });
-});
 
-browser.on("serviceDown", (service: dnssd.Service) => {
-    transforms.encode.write({
-        subject: "shim:/serviceDown"
-      , data: {
-            id: service.txt.id
-        }
+        transforms.encode.write({
+            subject: "shim:/serviceUp"
+          , data: {
+                address, port, id
+              , friendlyName: service.txt.fn
+              , currentApp: service.txt.rs
+            }
+        });
     });
-});
+
+    browser.on("serviceDown", (service: dnssd.Service) => {
+        const id = service.txt.id;
+
+        if (options.shouldWatchStatus) {
+            deregisterStatusListener(id);
+        }
+
+        transforms.encode.write({
+            subject: "shim:/serviceDown"
+          , data: { id }
+        });
+    });
+
+    browser.start();
+}
+
+
+interface StatusListener {
+    client: Client;
+    clientReceiver: Channel;
+}
+
+// Map of client connections
+const statusListeners = new Map<string, StatusListener>();
+
+/**
+ * Creates a connection to a receiver device and forwards
+ * RECEIVER_STATUS updates to the extension.
+ */
+function registerStatusListener (
+        host: string
+      , port: number
+      , id: string) {
+
+    const client = new Client();
+
+    const sourceId = "sender-0";
+    const destinationId = "receiver-0";
+
+    let heartbeatIntervalId: number;
+
+    client.connect({ host, port }, () => {
+        const clientConnection = client.createChannel(
+                sourceId, destinationId, NS_CONNECTION, "JSON");
+        const clientHeartbeat = client.createChannel(
+                sourceId, destinationId, NS_HEARTBEAT, "JSON");
+        const clientReceiver = client.createChannel(
+                sourceId, destinationId, NS_RECEIVER, "JSON");
+
+
+        clientReceiver.on("message", data => {
+            switch (data.type) {
+                case "CLOSE": {
+                    client.close();
+                    break;
+                }
+
+                case "RECEIVER_STATUS": {
+                    // Send update message
+                    transforms.encode.write({
+                        subject: "main:/receiverStatusUpdate"
+                      , data: {
+                            id
+                          , status: data.status
+                        }
+                    });
+
+                    break;
+                }
+            }
+        });
+
+        clientConnection.send({ type: "CONNECT" });
+        clientHeartbeat.send({ type: "PING" });
+        clientReceiver.send({ type: "GET_STATUS", requestId: 1 });
+
+        heartbeatIntervalId = setInterval(() => {
+            clientHeartbeat.send({ type: "PING" });
+        });
+
+        statusListeners.set(id, {
+            client
+          , clientReceiver
+        });
+    });
+
+    client.on("close", () => {
+        clearInterval(heartbeatIntervalId);
+    });
+}
+
+/**
+ * Closes status listener connection for a given receiver
+ * device.
+ */
+function deregisterStatusListener (id: string) {
+    const { client, clientReceiver } = statusListeners.get(id);
+
+    // Cleanup
+    clientReceiver.send({ type: "CLOSE" });
+    client.close();
+
+    // Remove from map
+    statusListeners.delete(id);
+}

ext/src/main.ts

@@ -539,6 +539,28 @@ browser.runtime.onConnect.addListener(port => {
 });
 
 
+const statusBridge = browser.runtime.connectNative(APPLICATION_NAME);
+const receiverStatusMap = new Map<string, any>();
+
+statusBridge.onMessage.addListener((message: Message)  => {
+    switch (message.subject) {
+        case "main:/receiverStatusUpdate": {
+            const { id, status } = message.data;
+            receiverStatusMap.set(id, status);
+
+            break;
+        }
+    }
+});
+
+statusBridge.postMessage({
+    subject: "bridge:/initialize"
+  , data: {
+        shouldWatchStatus: true
+    }
+});
+
+
 messageRouter.register("mirrorCast", message => {
     browser.tabs.sendMessage(mirrorCastTabId, message
           , { frameId: mirrorCastFrameId });