import EventRecord from "./EventRecord.js";

export default class EventContainer<E extends EventRecord = {}> {
  private events: { [K in keyof E]?: E[K][] } = {};

  public on<K extends keyof E>(eventName: K, eventHandler: E[K]): this {
    if (!this.events[eventName]) this.events[eventName] = [];
    this.events[eventName]!.push(eventHandler);
    return this;
  }

  public off<K extends keyof E>(eventName: K, eventHandler?: E[K]): this {
    const events = this.events[eventName];
    if (!events) return this;
    if (!eventHandler) {
      delete this.events[eventName];
    } else {
      const index = events.indexOf(eventHandler);
      if (index !== -1) events.splice(index, 1);
      if (events.length === 0) delete this.events[eventName];
    }
    return this;
  }

  protected hasEvent<K extends keyof E>(eventName: K): boolean {
    const events = this.events[eventName];
    if (!events) return false;
    return events.length > 0;
  }

  protected async emit<K extends keyof E>(
    eventName: K,
    ...args: Parameters<E[K]>
  ): Promise<ReturnType<E[K]>[]> {
    const events = this.events[eventName];
    if (!events) return [];

    const results: ReturnType<E[K]>[] = [];
    const promises: Promise<ReturnType<E[K]>>[] = [];

    for (const handler of events) {
      const result = handler(...args);
      if (result instanceof Promise) {
        promises.push(result);
      } else {
        results.push(result);
      }
    }

    return results.concat(await Promise.all(promises));
  }

  protected clearEvents(): void {
    delete (this as any).events;
  }
}