init

packages/server/src/utils/utils.event-emitter.ts

@@ -0,0 +1,64 @@
+type EventListener<T extends unknown[]> = (...args: T) => void | Promise<void>;
+
+type OnOptions = {
+  abortSignal?: AbortSignal;
+};
+
+class EventEmitter<T extends Record<string, (...args: ExplicitAny[]) => void | Promise<void>>> {
+  #listeners = new Map<keyof T, Set<EventListener<ExplicitAny>>>();
+
+  on = <K extends keyof T>(event: K, callback: EventListener<Parameters<T[K]>>, options: OnOptions = {}) => {
+    const { abortSignal } = options;
+    if (!this.#listeners.has(event)) {
+      this.#listeners.set(event, new Set());
+    }
+    const callbackClone = (...args: Parameters<T[K]>) => callback(...args);
+    const abortController = new AbortController();
+    const listeners = this.#listeners.get(event);
+    if (!listeners) {
+      throw new Error('Event registration failed');
+    }
+    abortSignal?.addEventListener('abort', abortController.abort);
+    listeners.add(callbackClone);
+    abortController.signal.addEventListener('abort', () => {
+      this.#listeners.set(event, listeners?.difference(new Set([callbackClone])));
+    });
+    return abortController.abort;
+  };
+
+  once = <K extends keyof T>(event: K, callback: EventListener<Parameters<T[K]>>, options: OnOptions = {}) => {
+    const abortController = new AbortController();
+    options.abortSignal?.addEventListener('abort', abortController.abort);
+    return this.on(
+      event,
+      async (...args) => {
+        abortController.abort();
+        await callback(...args);
+      },
+      {
+        ...options,
+        abortSignal: abortController.signal,
+      },
+    );
+  };
+
+  emit = <K extends keyof T>(event: K, ...args: Parameters<T[K]>) => {
+    const listeners = this.#listeners.get(event);
+    if (!listeners) {
+      return;
+    }
+    for (const listener of listeners) {
+      listener(...args);
+    }
+  };
+
+  emitAsync = async <K extends keyof T>(event: K, ...args: Parameters<T[K]>) => {
+    const listeners = this.#listeners.get(event);
+    if (!listeners) {
+      return;
+    }
+    await Promise.all(listeners.values().map((listener) => listener(...args)));
+  };
+}
+
+export { EventEmitter };