import { MaybeAsyncFunction } from "../types.js";

export type ElementPredicate<T = any> = (index: number, obj: T) => boolean;
export type ElementWeight<T = any> = (index: number, obj: T) => number;
export type RandomGenerator = () => number;

export type RandomOptions<T = any> = {
  predicate?: ElementPredicate<T>;
  weight?: ElementWeight<T>;
  random?: RandomGenerator;
};

export type MaybeAsyncElementPredicate<T = any> = MaybeAsyncFunction<ElementPredicate<T>>;
export type MaybeAsyncElementWeight<T = any> = MaybeAsyncFunction<ElementWeight<T>>;

export type AsyncRandomOptions<T = any> = {
  predicate?: MaybeAsyncElementPredicate<T>;
  weight?: MaybeAsyncElementWeight<T>;
  random?: RandomGenerator;
};

type RandomElementFound<T> = {
  found: true;
  element: T;
  index: number;
};
type RandomElementNotFound = {
  found: false;
  element: undefined;
  index: -1;
};
export type RandomElement<T> = RandomElementFound<T> | RandomElementNotFound;