import { Readable, Subscriber } from './public.js';

/** Cleanup logic callback. */
export type Invalidator<T> = (value?: T) => void;

/** Pair of subscriber and invalidator. */
export type SubscribeInvalidateTuple<T> = [Subscriber<T>, Invalidator<T>];

/** One or more `Readable`s. */
export type Stores =
  | Readable<any>
  | [Readable<any>, ...Array<Readable<any>>]
  | Array<Readable<any>>;

/** One or more values from `Readable` stores. */
export type StoresValues<T> = T extends Readable<infer U>
  ? U
  : { [K in keyof T]: T[K] extends Readable<infer U> ? U : never };