Add @mediabunny/ac3 extension package

packages/ac3/src/worker-client.ts

@@ -0,0 +1,69 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import { assert, type WorkerCommand, type WorkerResponse, type WorkerResponseData } from './shared';
+// @ts-expect-error An esbuild plugin handles this, TypeScript doesn't need to understand
+import createWorker from './codec.worker';
+
+let workerPromise: Promise<Worker> | null;
+let nextMessageId = 0;
+const pendingMessages = new Map<number, {
+	resolve: (value: WorkerResponseData) => void;
+	reject: (reason?: unknown) => void;
+}>();
+
+export const sendCommand = async <T extends string>(
+	command: WorkerCommand & { type: T },
+	transferables?: Transferable[],
+) => {
+	const worker = await ensureWorker();
+
+	return new Promise<WorkerResponseData & { type: T }>((resolve, reject) => {
+		const id = nextMessageId++;
+		pendingMessages.set(id, {
+			resolve: resolve as (value: WorkerResponseData) => void,
+			reject,
+		});
+
+		if (transferables) {
+			worker.postMessage({ id, command }, transferables);
+		} else {
+			worker.postMessage({ id, command });
+		}
+	});
+};
+
+const ensureWorker = () => {
+	return workerPromise ??= (async () => {
+		// eslint-disable-next-line @typescript-eslint/no-unsafe-call
+		const worker = (await createWorker()) as Worker;
+
+		const onMessage = (data: WorkerResponse) => {
+			const pending = pendingMessages.get(data.id);
+			assert(pending !== undefined);
+
+			pendingMessages.delete(data.id);
+			if (data.success) {
+				pending.resolve(data.data);
+			} else {
+				pending.reject(data.error);
+			}
+		};
+
+		if (worker.addEventListener) {
+			worker.addEventListener('message', event => onMessage(event.data as WorkerResponse));
+		} else {
+			const nodeWorker = worker as unknown as {
+				on: (event: string, listener: (data: never) => void) => void;
+			};
+			nodeWorker.on('message', onMessage);
+		}
+
+		return worker;
+	})();
+};