export type Result<T, E = Error> = { ok: true; value: T } | { ok: false; error: E };

export const ok = <T>(value: T): Result<T, never> => ({ ok: true, value });
export const err = <E>(error: E): Result<never, E> => ({ ok: false, error });

export function isOk<T, E>(r: Result<T, E>): r is { ok: true; value: T } {
  return r.ok;
}

export function isErr<T, E>(r: Result<T, E>): r is { ok: false; error: E } {
  return !r.ok;
}

export function unwrap<T, E>(r: Result<T, E>): T {
  if (r.ok) return r.value;
  throw r.error instanceof Error ? r.error : new Error(String(r.error));
}

export function map<T, U, E>(r: Result<T, E>, fn: (v: T) => U): Result<U, E> {
  return r.ok ? ok(fn(r.value)) : r;
}

export async function tryAsync<T>(fn: () => Promise<T>): Promise<Result<T, Error>> {
  try {
    return ok(await fn());
  } catch (e) {
    return err(e instanceof Error ? e : new Error(String(e)));
  }
}