import { EventEmitter } from 'events';

/**
 * Asynchronous event emitter that adds
 * the function ```emitAsync()```.
 */
export class AsyncEventEmitter extends EventEmitter {
    public emitAsync(type: string | symbol, ...args: any[]): Promise<boolean> {
        return new Promise<boolean>((resolve, reject) => {
            const handlers: Function[] = this.listeners(type); // eslint-disable-line
            if (handlers.length === 0) {
                return resolve(false);
            }

            const promises: Array<Promise<void>> = [];
            handlers.forEach((handler) => {
                promises.push(handler(...args));
            });

            Promise.all(promises)
                .then(() => {
                    resolve(true);
                })
                .catch(reject);
        });
    }
}