import type { Args, GenericFn, GenericResolver } from "../HKT";
import type { List, Pair } from "../List";

/**
 * Convert a {@link List} (i.e., fixed-length tuple) of key-value pairs into an object.
 *
 * Sig: `<K extends PropertyKey, V>(entries: List<readonly [K, V]>) => Record<K, V>`
 */
export type FromEntries<Entries extends List<Pair<PropertyKey, unknown>>> =
  { [K in Entries[number] as K[0]]: K[1] } extends infer R ? { [K in keyof R]: R[K] } : never;

interface Resolver extends GenericResolver<[List<Pair<PropertyKey, unknown>>], object> {
  on1: ([entries]: Args<this>) => [
    [],
    Record<(typeof entries)[number][0], (typeof entries)[number][1]>,
  ];
}

/**
 * [Fn] Convert a {@link List} (i.e., fixed-length tuple) of key-value pairs into an object.
 *
 * Sig: `<K extends PropertyKey, V>(entries: List<readonly [K, V]>) => Record<K, V>`
 */
export default interface FromEntriesFn extends GenericFn<Resolver> {
  def: ([entries]: Args<this>) => FromEntries<typeof entries>;
}