// @ts-ignore - Only used in doc comments
import type { Pick } from "./Pick";
// @ts-ignore - Only used in doc comments
import type PickFn from "./Pick";
import type { Args, GenericFn, GenericResolver } from "../HKT";
import type { Eq, IsPropertyKeyLiteral } from "../helpers";

/**
 * Less strict version of {@link Pick}.The **W** suffix (short for **W**idening) means that the key
 * type is widened to `PropertyKey`.
 *
 * Sig: `(k: PropertyKey, o: object) => object`
 */
// We do not use the built-in `Pick` type because it does not keep the readonly modifier.
export type PickW<K extends PropertyKey, O> = {
  [P in keyof O as P extends K ? P : never]: O[P];
};

interface Resolver extends GenericResolver<[PropertyKey, object], object> {
  on1_: ([k]: Args<this>) => [[object], object];
  on_1: ([, o]: Args<this>) => [[PropertyKey], object];
  on11: ([k, o]: Args<this>) => [
    [],
    IsPropertyKeyLiteral<typeof k> extends true ?
      { [P in keyof typeof o as P extends typeof k ? P : never]: (typeof o)[P] } extends infer R ?
        Eq<R, typeof o> extends true ?
          typeof o
        : R
      : never
    : { readonly [P in typeof k]: (typeof o)[keyof typeof o] } extends infer R ?
      Eq<R, typeof o> extends true ?
        typeof o
      : R
    : never,
  ];
}

/**
 * [Fn] Less strict version of {@link Omit}.The **W** suffix (short for **W**idening) means that the
 * key type is widened to `PropertyKey`.
 *
 * Sig: `(k: PropertyKey, o: object) => object`
 */
export default interface PickWFn extends GenericFn<Resolver> {
  def: ([k, o]: Args<this>) => {
    [P in keyof typeof o as P extends typeof k ? P : never]: (typeof o)[P];
  };
}