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/** The callback type. */type Callback = (...args: any[]) => any | Promise<any>;
/** A listener type. */type Listener = Callback & { __once__?: true; };
/** The name of an event. */type EventName = string | number;
type EventsType =	& { [key: string]: Callback; }	& { [key: number]: Callback; }	;
/** * The event emitter. */export class EventEmitter <E extends EventsType = { }>{		/**	 * This is where the events and listeners are stored.	 */	private _events_: Map<keyof E, Set<Listener>> = new Map();		/**	 * Listen for a typed event.	 * @param event The typed event name to listen for.	 * @param listener The typed listener function.	 */	public on <K extends keyof E> (event: K, listener: E[K]): this;		/**	 * Listen for an event.	 * @param event The event name to listen for.	 * @param listener The listener function.	 */	public on (event: EventName, listener: Callback): this	{		if (!this._events_.has(event)) this._events_.set(event, new Set());		this._events_.get(event)!.add(listener);		return this;	}		/**	 * Listen for a typed event once.	 * @param event The typed event name to listen for.	 * @param listener The typed listener function.	 */	public once <K extends keyof E> (event: K, listener: E[K]): this;		/**	 * Listen for an event once.	 * @param event The event name to listen for.	 * @param listener The listener function.	 */	public once (event: EventName, listener: Callback): this	{		const l: Listener = listener;		l.__once__ = true;		return this.on(event, l as any);	}		/**	 * Remove a specific listener in the event emitter on a specific	 * typed event.	 * @param event The typed event name.	 * @param listener The typed event listener function.	 */	public off <K extends keyof E> (event: K, listener: E[K]): this;		/**	 * Remove all listeners on a specific typed event.	 * @param event The typed event name.	 */	public off <K extends keyof E> (event: K): this;		/**	 * Remove all events from the event listener.	 */	public off (): this;		/**	 * Remove a specific listener on a specific event if both `event`	 * and `listener` is defined, or remove all listeners on a	 * specific event if only `event` is defined, or lastly remove	 * all listeners on every event if `event` is not defined.	 * @param event The event name.	 * @param listener The event listener function.	 */	public off (event?: EventName, listener?: Callback): this	{		if ((event === undefined || event === null) && listener)			throw new Error("Why is there a listener defined here?");		else if ((event === undefined || event === null) && !listener)			this._events_.clear();		else if (event && !listener)			this._events_.delete(event);		else if (event && listener && this._events_.has(event))		{			const _ = this._events_.get(event)!;			_.delete(listener);			if (_.size === 0) this._events_.delete(event);		} else;		return this;	}		/**	 * Emit a typed event without waiting for each listener to	 * return.	 * @param event The typed event name to emit.	 * @param args The arguments to pass to the typed listeners.	 */	public emitSync <K extends keyof E> (event: K, ...args: Parameters<E[K]>): this;		/**	 * Emit an event without waiting for each listener to return.	 * @param event The event name to emit.	 * @param args The arguments to pass to the listeners.	 */	public emitSync (event: EventName, ...args: Parameters<Callback>): this	{		if (!this._events_.has(event)) return this;		const _ = this._events_.get(event)!;		for (let [, listener ] of _.entries())		{			const r = listener(...args);			if (r instanceof Promise) r.catch(console.error);			if (listener.__once__)			{				delete listener.__once__;				_.delete(listener);			}		}		if (_.size === 0) this._events_.delete(event);		return this;	}		/**	 * Emit a typed event and wait for each typed listener to return.	 * @param event The typed event name to emit.	 * @param args The arguments to pass to the typed listeners.	 */	public async emit <K extends keyof E> (event: K, ...args: Parameters<E[K]>): Promise<this>;		/**	 * Emit an event and wait for each listener to return.	 * @param event The event name to emit.	 * @param args The arguments to pass to the listeners.	 */	public async emit (event: EventName, ...args: Parameters<Callback>): Promise<this>	{		if (!this._events_.has(event)) return this;		const _ = this._events_.get(event)!;		for (let [, listener ] of _.entries())		{			try			{				await listener(...args);				if (listener.__once__)				{					delete listener.__once__;					_.delete(listener);				}			} catch (error)			{				console.error(error);			}		}		if (_.size === 0) this._events_.delete(event);		return this;	}		/**	 * The same as emitSync, but wait for each typed listener to	 * return before calling the next typed listener.	 * @param event The typed event name.	 * @param args The arguments to pass to the typed listeners.	 */	public queue <K extends keyof E> (event: K, ...args: Parameters<E[K]>): this;		/**	 * The same as emitSync, but wait for each listener to return	 * before calling the next listener.	 * @param event The event name.	 * @param args The arguments to pass to the listeners.	 */	public queue (event: EventName, ...args: Parameters<Callback>): this	{		(async () => await this.emit(event, ...args as any))().catch(console.error);		return this;	}		/**	 * Wait for a typed event to be emitted and return the arguments.	 * @param event The typed event name to wait for.	 * @param timeout An optional amount of milliseconds to wait	 * before throwing.	 */	public pull <K extends keyof E> (event: K, timeout?: number): Promise<Parameters<E[K]>>;	/**	 * Wait for an event to be emitted and return the arguments.	 * @param event The event name to wait for.	 * @param timeout An optional amount of milliseconds to wait	 * before throwing.	 */	public pull (event: EventName, timeout?: number): Promise<Parameters<Callback>>	{		return new Promise(async (resolve, reject) => {			let timeoutId: number | null						let listener = (...args: any[]) => {				if (timeoutId !== null) clearTimeout(timeoutId);				resolve(args);			};						timeoutId = typeof timeout !== "number"				? null				: setTimeout(() => (this.off(event, listener as any), reject(					new Error("Timed out!")				)));						this.once(event, listener as any);		});	}		/**	 * Clone *this* event emitter.	 * @param cloneListeners Also copy listeners to the new emitter. (defaults to true)	 */	public clone (cloneListeners = true): EventEmitter<E> {		const emitter = new EventEmitter<any>();		if (cloneListeners) {			for (const [key, set] of this._events_) emitter._events_.set(key, new Set([...set]));		}		return emitter;	}	}
export default EventEmitter;