import type { Semigroup, Semigroup$GetConstruct, Semigroup$GetTypeClass } from ".";
import type { Args, Call2W, Cons, Fn } from "../../HKT";
import type { IsAny } from "../../helpers";

/**
 * Concat two {@link Semigroup} instances.
 *
 * Sig: `(s1: Semigroup, s2: Semigroup) => Semigroup`
 *
 * Type safety is **not guaranteed** if `S1` and `S2` are not of the same construct.
 */
export type Concat<S1 extends Semigroup, S2 extends Semigroup> =
  [IsAny<S1>, IsAny<S2>] extends [true, true] ? Semigroup
  : IsAny<S1> extends true ? Semigroup$GetConstruct<S2>
  : IsAny<S2> extends true ? Semigroup$GetConstruct<S1>
  : Call2W<Semigroup$GetTypeClass<S1>["Concat"], S1, S2>;

/**
 * [Fn] Concat two {@link Semigroup} instances.
 *
 * Sig: `<S extends Cons<Semigroup>>(s1: S, s2: S) => S`
 */
export default interface ConcatFn<S extends Cons<Semigroup>> extends Fn<[S, S], S> {
  def: ([s1, s2]: Args<this>) => Concat<typeof s1, typeof s2>;
}