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

/**
 * Apply a function to each element of a {@link List} (i.e., fixed-length tuple).
 *
 * Sig: `<T, U>(f: (x: T) => U, xs: List<T>) => List<U>`
 */
export type Map<F extends Fn1, TS extends List> = {
  [K in keyof TS]: Call1W<F, TS[K]>;
};

interface Resolver extends GenericResolver<[Fn1, List], List> {
  on1_: ([f]: Args<this>) => [[List<Param0<typeof f>>], List<Return<typeof f>>];
  on_1: ([, xs]: Args<this>) => [[Fn1<(typeof xs)[number]>], List];
  on11: ([f, xs]: Args<this>) => [[], List<GenericReturn1W<typeof f, (typeof xs)[number]>>];
  on__r: ([, , r]: Args<this>) => [Fn1<never, (typeof r)[number]>, List];
  on1_r: ([f, , r]: Args<this>) => [List<Param0<typeof f>>];
  on_1r: ([, xs, r]: Args<this>) => [Fn1<(typeof xs)[number], (typeof r)[number]>];
}

/**
 * [Fn] Apply a function to each element of a {@link List} (i.e., fixed-length tuple).
 *
 * Sig: `<T, U>(f: (x: T) => U, xs: List<T>) => List<U>`
 */
export default interface MapFn extends GenericFn<Resolver> {
  def: ([f, xs]: Args<this>) => Map<typeof f, typeof xs>;
}