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

/**
 * Determine if every element in a {@link List} (i.e., fixed-length tuple) satisfies a predicate.
 *
 * Sig: `<T>(pred: (x: T) => boolean, xs: List<T>) => boolean`
 */
export type Every<Pred extends Fn1<never, boolean>, TS extends List> =
  number extends TS["length"] ? boolean
  : TS extends readonly [infer Head, ...infer Tail] ?
    Call1W<Pred, Head> extends true ?
      Every<Pred, Tail>
    : false
  : true;

interface Resolver extends GenericResolver<[Fn1<never, boolean>, List], boolean> {
  on1_: ([pred]: Args<this>) => [[List<Param0<typeof pred>>], boolean];
  on_1: ([, xs]: Args<this>) => [[Fn1<(typeof xs)[number], boolean>], boolean];
  on11: ([pred, xs]: Args<this>) => [[], boolean];
}

/**
 * [Fn] Determine if every element in a {@link List} (i.e., fixed-length tuple) satisfies a
 * predicate.
 *
 * Sig: `<T>(pred: (x: T) => boolean, xs: List<T>) => boolean`
 */
export default interface EveryFn extends GenericFn<Resolver> {
  def: ([pred, xs]: Args<this>) => Every<typeof pred, typeof xs>;
}