Improve cast client module receiver messages handling

app/src/bridge/components/cast/Session.ts

@@ -5,9 +5,9 @@ import { Channel } from "castv2";
 import { sendMessage } from "../../lib/nativeMessaging";
 
 import { ReceiverDevice } from "../../types";
-import { ReceiverApplication, ReceiverMessage, SenderMessage } from "./types";
+import { ReceiverMessage } from "./types";
 
-import CastClient, { NS_CONNECTION, NS_HEARTBEAT, NS_RECEIVER } from "./client";
+import CastClient, { NS_CONNECTION, NS_HEARTBEAT } from "./client";
 
 type OnSessionCreatedCallback = (sessionId: string) => void;
 
@@ -15,10 +15,6 @@ export default class Session extends CastClient {
     // Assigned by the receiver once the session is established
     public sessionId?: string;
 
-    // Platform messaging
-    private receiverChannel?: Channel;
-    private receiverRequestId = 0;
-
     // Receiver app messaging
     private transportId?: string;
     private transportConnection?: Channel;
@@ -64,7 +60,7 @@ export default class Session extends CastClient {
                  * request response.
                  */
                 if (!this.sessionId) {
-                    // Launch message response only
+                    // Match request ID on the response to the launch request ID.
                     if (message.requestId !== this.launchRequestId) {
                         break;
                     }
@@ -159,18 +155,6 @@ export default class Session extends CastClient {
         channel.send(message);
     }
 
-    sendReceiverMessage(message: DistributiveOmit<SenderMessage, "requestId">) {
-        if (!this.receiverChannel) {
-            this.receiverChannel = this.createChannel(NS_RECEIVER);
-            this.receiverChannel.on("message", this.onReceiverMessage);
-        }
-
-        const requestId = this.receiverRequestId++;
-        this.receiverChannel?.send({ ...message, requestId });
-
-        return requestId;
-    }
-
     constructor(
         private appId: string,
         private receiverDevice: ReceiverDevice,
@@ -178,6 +162,25 @@ export default class Session extends CastClient {
     ) {
         super();
 
+        super.connect(receiverDevice.host, {
+            onHeartbeat: () => {
+                // Include transport heartbeat with platform heartbeat
+                if (this.transportHeartbeat) {
+                    this.transportHeartbeat.send({ type: "PING" });
+                }
+            },
+            onReceiverMessage: message => {
+                this.onReceiverMessage(message);
+            }
+        }).then(() => {
+            // Send a launch request and store the request ID for reference
+            this.launchRequestId = this.sendReceiverMessage({
+                type: "LAUNCH",
+                appId: this.appId
+            });
+        });
+
+        // Handle client connection closed
         this.client.on("close", () => {
             if (this.sessionId) {
                 sendMessage({
@@ -186,19 +189,5 @@ export default class Session extends CastClient {
                 });
             }
         });
-
-        super.connect(receiverDevice.host, {
-            onHeartbeat: () => {
-                // Include transport heartbeat with platform heartbeat
-                if (this.transportHeartbeat) {
-                    this.transportHeartbeat.send({ type: "PING" });
-                }
-            }
-        }).then(() => {
-            this.launchRequestId = this.sendReceiverMessage({
-                type: "LAUNCH",
-                appId: this.appId
-            });
-        });
     }
 }

app/src/bridge/components/cast/client.ts

@@ -2,6 +2,8 @@
 
 import { Channel, Client } from "castv2";
 
+import { ReceiverMessage, SenderMessage } from "./types";
+
 export const NS_CONNECTION = "urn:x-cast:com.google.cast.tp.connection";
 export const NS_HEARTBEAT = "urn:x-cast:com.google.cast.tp.heartbeat";
 export const NS_RECEIVER = "urn:x-cast:com.google.cast.receiver";
@@ -11,6 +13,7 @@ const HEARTBEAT_INTERVAL_MS = 5000;
 
 interface CastClientConnectOptions {
     port?: number;
+    onReceiverMessage?: (message: ReceiverMessage) => void;
     onHeartbeat?: () => void;
 }
 
@@ -21,6 +24,10 @@ export default class CastClient {
     protected heartbeatChannel?: Channel;
     protected heartbeatIntervalId?: NodeJS.Timeout;
 
+    // Platform messaging
+    private receiverChannel?: Channel;
+    private receiverRequestId = 0;
+
     constructor(
         protected sourceId = "sender-0",
         protected destinationId = "receiver-0"
@@ -43,6 +50,18 @@ export default class CastClient {
         );
     }
 
+    /**
+     * Sends a message on the receiver channel with the correct
+     * request ID.
+     */
+    sendReceiverMessage(message: DistributiveOmit<SenderMessage, "requestId">) {
+        if (!this.receiverChannel) return;
+
+        const requestId = this.receiverRequestId++;
+        this.receiverChannel.send({ ...message, requestId });
+        return requestId;
+    }
+
     /**
      * Connects to a cast receiver at a given host, returning a
      * promise that resolves once the client is connected.
@@ -57,25 +76,33 @@ export default class CastClient {
                 }
             });
 
-            const connectOpts = {
+            this.client.connect(
-                host,
+                {
-                port: options?.port ?? DEFAULT_PORT
+                    host,
-            };
+                    port: options?.port ?? DEFAULT_PORT
+                },
+                // On connection callback
+                () => {
+                    this.connectionChannel = this.createChannel(NS_CONNECTION);
+                    this.heartbeatChannel = this.createChannel(NS_HEARTBEAT);
 
-            this.client.connect(connectOpts, () => {
+                    // Handle receiver messages
-                this.connectionChannel = this.createChannel(NS_CONNECTION);
+                    this.receiverChannel = this.createChannel(NS_RECEIVER);
-                this.heartbeatChannel = this.createChannel(NS_HEARTBEAT);
+                    this.receiverChannel.on("message", message => {
+                        options?.onReceiverMessage?.(message);
+                    });
 
-                this.connectionChannel.send({ type: "CONNECT" });
+                    this.connectionChannel.send({ type: "CONNECT" });
-                this.heartbeatChannel.send({ type: "PING" });
+                    this.heartbeatChannel.send({ type: "PING" });
 
-                this.heartbeatIntervalId = setInterval(() => {
+                    this.heartbeatIntervalId = setInterval(() => {
-                    this.heartbeatChannel?.send({ type: "PING" });
+                        this.heartbeatChannel?.send({ type: "PING" });
-                    options?.onHeartbeat?.();
+                        options?.onHeartbeat?.();
-                }, HEARTBEAT_INTERVAL_MS);
+                    }, HEARTBEAT_INTERVAL_MS);
 
-                resolve();
+                    resolve();
-            });
+                }
+            );
         });
     }
 

app/src/bridge/components/cast/remote.ts

@@ -1,6 +1,6 @@
 "use strict";
 
-import CastClient, { NS_RECEIVER } from "./client";
+import CastClient from "./client";
 
 import {
     MediaStatus,
@@ -27,13 +27,12 @@ export default class Remote extends CastClient {
 
     constructor(private host: string, private options?: CastRemoteOptions) {
         super();
-        this.connect(host).then(() => {
+        super.connect(host, {
-            // Request receiver status
+            onReceiverMessage: message => {
-            const receiverChannel = this.createChannel(NS_RECEIVER);
-            receiverChannel.on("message", message => {
                 this.onReceiverMessage(message);
-            });
+            }
-            receiverChannel.send({ type: "GET_STATUS", requestId: 1 });
+        }).then(() => {
+            this.sendReceiverMessage({ type: "GET_STATUS" });
         });
     }
 
@@ -47,7 +46,7 @@ export default class Remote extends CastClient {
      * On initial connection, a `GET_STATUS` message is sent that
      * results in a `RECEIVER_STATUS` response. If an application
      * is running, get the transport ID and make a connection to
-     * fetch media status updates.
+     * receive media status updates.
      */
     private onReceiverMessage(message: ReceiverMessage) {
         if (message.type !== "RECEIVER_STATUS") {
@@ -62,7 +61,7 @@ export default class Remote extends CastClient {
                 this.options?.onApplicationClose?.();
             }
         }
-        
+
         // Update status before possible transport init
         this.options?.onReceiverStatusUpdate?.(message.status);