Misc fixes/improvements from WIP branches

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

@@ -0,0 +1,90 @@
+"use strict";
+
+import { Channel, Client } from "castv2";
+
+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";
+
+const DEFAULT_PORT = 8009;
+const HEARTBEAT_INTERVAL_MS = 5000;
+
+interface CastClientConnectOptions {
+    port?: number;
+    onHeartbeat?: () => void;
+}
+
+export default class CastClient {
+    protected client = new Client();
+
+    protected connectionChannel?: Channel;
+    protected heartbeatChannel?: Channel;
+    protected heartbeatIntervalId?: NodeJS.Timeout;
+
+    constructor(
+        protected sourceId = "sender-0",
+        protected destinationId = "receiver-0"
+    ) {}
+
+    /**
+     * Create a channel on the client connection with a given
+     * namespace.
+     */
+    protected createChannel(
+        namespace: string,
+        sourceId = this.sourceId,
+        destinationId = this.destinationId
+    ) {
+        return this.client.createChannel(
+            sourceId,
+            destinationId,
+            namespace,
+            "JSON"
+        );
+    }
+
+    /**
+     * Connects to a cast receiver at a given host, returning a
+     * promise that resolves once the client is connected.
+     */
+    connect(host: string, options?: CastClientConnectOptions) {
+        return new Promise<void>((resolve, reject) => {
+            // Handle errors
+            this.client.on("error", reject);
+            this.client.on("close", () => {
+                if (this.heartbeatChannel && this.heartbeatIntervalId) {
+                    clearInterval(this.heartbeatIntervalId);
+                }
+            });
+
+            const connectOpts = {
+                host,
+                port: options?.port ?? DEFAULT_PORT
+            };
+
+            this.client.connect(connectOpts, () => {
+                this.connectionChannel = this.createChannel(NS_CONNECTION);
+                this.heartbeatChannel = this.createChannel(NS_HEARTBEAT);
+
+                this.connectionChannel.send({ type: "CONNECT" });
+                this.heartbeatChannel.send({ type: "PING" });
+
+                this.heartbeatIntervalId = setInterval(() => {
+                    this.heartbeatChannel?.send({ type: "PING" });
+                    options?.onHeartbeat?.();
+                }, HEARTBEAT_INTERVAL_MS);
+
+                resolve();
+            });
+        });
+    }
+
+    disconnect() {
+        if (this.heartbeatIntervalId) {
+            clearInterval(this.heartbeatIntervalId);
+        }
+
+        this.connectionChannel?.send({ type: "CLOSE" });
+        this.client.close();
+    }
+}