export type AsyncHandler<T> = {
  resolve: (t: T | PromiseLike<T>) => void;
  reject: (err: any) => void;
};

type ExtractResult<Args extends any[]> = Args extends [AsyncHandler<infer T>, ...any[]] ? T : never;

type ExtractArgs<Args extends any[]> = Args extends [AsyncHandler<any>, ...infer Rest] ? Rest : never;

export function useAsyncEmits<Emits extends Record<string, any[]>>(emits: (evt: any, ...args: any[]) => void) {
  const emitsAsync = <Evt extends keyof Emits>(evt: Evt, ...args: ExtractArgs<Emits[Evt]>) =>
    new Promise<ExtractResult<Emits[Evt]>>((resolve, reject) => {
      emits(evt, { resolve, reject }, ...args);
    });

  return emitsAsync;
}

export function handleAsync<T, Args extends any[]>(handler: (...args: Args) => Promise<T>) {
  return ({ resolve, reject }: AsyncHandler<T>, ...args: Args) => handler(...args).then(resolve, reject);
}