type EventCallback = (...args: unknown[]) => void;
type AnyEventCallback = (event: string, ...args: unknown[]) => void;

export interface RuntimeEventMap {
  "runtime:ready": { startedAt: number };
  "scene:changed": { current: string; previous?: string };
  "game:rendered": undefined;
  "game:frame-rendered": undefined;
}

export class RuntimeEvents {
  private events = new Map<string, Set<EventCallback>>();
  private anyEventCallbacks = new Set<AnyEventCallback>();

  on(event: string, callback: EventCallback): () => void {
    if (!this.events.has(event)) {
      this.events.set(event, new Set());
    }

    this.events.get(event)!.add(callback);
    return () => this.off(event, callback);
  }

  off(event: string, callback: EventCallback): void {
    const callbacks = this.events.get(event);
    if (!callbacks) {
      return;
    }

    callbacks.delete(callback);
    if (callbacks.size === 0) {
      this.events.delete(event);
    }
  }

  once(event: string, callback: EventCallback): () => void {
    const wrapped: EventCallback = (...args) => {
      try {
        callback(...args);
      } finally {
        this.off(event, wrapped);
      }
    };
    return this.on(event, wrapped);
  }

  emit(event: string, ...args: unknown[]): void {
    this.anyEventCallbacks.forEach((cb) => {
      try {
        cb(event, ...args);
      } catch (error) {
        console.error(`RuntimeEvents: tap listener failed for "${event}"`, error);
      }
    });

    const callbacks = this.events.get(event);
    if (!callbacks) {
      return;
    }

    callbacks.forEach((cb) => {
      try {
        cb(...args);
      } catch (error) {
        console.error(`RuntimeEvents: listener failed for "${event}"`, error);
      }
    });
  }

  clear(): void {
    this.events.clear();
    this.anyEventCallbacks.clear();
  }

  getEventCount(): number {
    return this.events.size;
  }

  onAny(callback: AnyEventCallback): () => void {
    this.anyEventCallbacks.add(callback);
    return () => {
      this.anyEventCallbacks.delete(callback);
    };
  }
}