import type {
  Args,
  Call1W,
  Fn1,
  GenericFn,
  GenericResolver,
  GenericReturn1W,
  Param0,
  Return,
} from "../HKT";

/**
 * Apply a function to each value in an object.
 *
 * Sig: `<T, U>(f: (x: T => U), o: Record<PropertyKey, T>) => Record<PropertyKey, U>`
 */
export type MapValues<F extends Fn1, O extends object> = {
  [K in keyof O]: Call1W<F, O[K]>;
};

interface Resolver extends GenericResolver<[Fn1, object], object> {
  on1_: ([f]: Args<this>) => [
    [Record<PropertyKey, Param0<typeof f>>],
    Record<PropertyKey, Return<typeof f>>,
  ];
  on_1: ([, o]: Args<this>) => [[Fn1<(typeof o)[keyof typeof o]>], object];
  on11: ([f, o]: Args<this>) => [
    [],
    Record<keyof typeof o, GenericReturn1W<typeof f, (typeof o)[keyof typeof o]>>,
  ];
}

/**
 * [Fn] Apply a function to each value in an object.
 *
 * Sig: `<T, U>(f: (x: T => U), o: Record<PropertyKey, T>) => Record<PropertyKey, U>`
 */
export default interface MapValuesFn extends GenericFn<Resolver> {
  def: ([f, o]: Args<this>) => MapValues<typeof f, typeof o>;
}