// @ts-ignore - `Some` and `None` are only used in doc comments
import type { None, Option, Some } from ".";
import type { Map } from "./Map";
import type { GenericReturn1W } from "..";
import type { Args, Fn1, GenericFn, GenericResolver, Param0W, ReturnW } from "../HKT";
import type { Applicative, TypeClass$$Applicative } from "../typeclass";

declare module "../typeclass/Applicative" {
  interface ApplicativeImpl {
    Option: ImplApplicativeFor<Option, Option$$Applicative>;
  }
}

/**
 * Implementation of the {@link Applicative} type class for {@link Option}.
 */
export interface Option$$Applicative extends TypeClass$$Applicative<Option> {
  Ap: Option$$Applicative$ApFn;
  Of: Option$$Applicative$OfFn;
}

type ExtractOption<O extends Option<unknown>> = O extends Option<infer T> ? T : never;

interface ApResolver extends GenericResolver<[Option<Fn1>, Option<unknown>], Option<unknown>> {
  on1_: ([fab]: Args<this>) => [
    [Param0W<ExtractOption<typeof fab>>],
    ReturnW<ExtractOption<typeof fab>>,
  ];
  on_1: ([, f]: Args<this>) => [[Option<Fn1<ExtractOption<typeof f>, unknown>>], Option<unknown>];
  on11: ([fab, f]: Args<this>) => [
    [],
    Option<GenericReturn1W<ExtractOption<typeof fab>, ExtractOption<typeof f>>>,
  ];
}
/**
 * [Fn] Apply an {@link Option} of a function to an {@link Option} of a value if both are
 * {@link Some}, otherwise return {@link None}.
 */
interface Option$$Applicative$ApFn extends GenericFn<ApResolver> {
  def: ([fab, f]: Args<this>) => Option$$Applicative$Ap<typeof fab, typeof f>;
}
type Option$$Applicative$Ap<FAB extends Option<Fn1>, F extends Option> =
  FAB extends Some<infer G extends Fn1<ExtractOption<F>, unknown>> ? Map<G, F> : None;

interface OfResolver extends GenericResolver<[unknown], Option<unknown>> {
  on1: ([x]: Args<this>) => [[], Option<typeof x>];
}
/**
 * [Fn] Build an {@link Option} from a value (wrapping it in a {@link Some}).
 */
interface Option$$Applicative$OfFn extends GenericFn<OfResolver> {
  def: ([x]: Args<this>) => Option$$Applicative$Of<typeof x>;
}
type Option$$Applicative$Of<T> = Some<T>;