// See: https://github.com/facebook/metro/blob/v0.83.2/packages/metro-runtime/src/modules/vendor/eventemitter3.js

/**
 * `object` should be in either of the following forms:
 * ```
 * interface EventTypes {
 *   'event-with-parameters': any[]
 *   'event-with-example-handler': (...args: any[]) => void
 * }
 * ```
 */
export type ValidEventTypes = string | symbol | object;

export type EventNames<T extends ValidEventTypes> = T extends string | symbol ? T : keyof T;

export type ArgumentMap<T extends object> = {
  [K in keyof T]: T[K] extends (...args: any[]) => void ? Parameters<T[K]> : T[K] extends any[] ? T[K] : any[];
};

export type EventListener<T extends ValidEventTypes, K extends EventNames<T>> = T extends string | symbol
  ? (...args: any[]) => void
  : (...args: ArgumentMap<Exclude<T, string | symbol>>[Extract<K, keyof T>]) => void;

export type EventArgs<T extends ValidEventTypes, K extends EventNames<T>> = Parameters<EventListener<T, K>>;

export class EventEmitter<EventTypes extends ValidEventTypes = string | symbol, Context extends any = any> {
  static prefixed: string | boolean;

  /** Return an array listing the events for which the emitter has registered listeners. */
  eventNames(): Array<EventNames<EventTypes>>;

  /** Return the listeners registered for a given event. */
  listeners<T extends EventNames<EventTypes>>(event: T): Array<EventListener<EventTypes, T>>;

  /** Return the number of listeners listening to a given event. */
  listenerCount(event: EventNames<EventTypes>): number;

  /** Calls each of the listeners registered for a given event. */
  emit<T extends EventNames<EventTypes>>(event: T, ...args: EventArgs<EventTypes, T>): boolean;

  /** Add a listener for a given event. */
  on<T extends EventNames<EventTypes>>(event: T, fn: EventListener<EventTypes, T>, context?: Context): this;
  addListener<T extends EventNames<EventTypes>>(event: T, fn: EventListener<EventTypes, T>, context?: Context): this;

  /** Add a one-time listener for a given event. */
  once<T extends EventNames<EventTypes>>(event: T, fn: EventListener<EventTypes, T>, context?: Context): this;

  /** Remove the listeners of a given event. */
  removeListener<T extends EventNames<EventTypes>>(
    event: T,
    fn?: EventListener<EventTypes, T>,
    context?: Context,
    once?: boolean
  ): this;
  off<T extends EventNames<EventTypes>>(
    event: T,
    fn?: EventListener<EventTypes, T>,
    context?: Context,
    once?: boolean
  ): this;

  /** Remove all listeners, or those of the specified event. */
  removeAllListeners(event?: EventNames<EventTypes>): this;
}

export default EventEmitter;