/**
 * Shallow structural equality over own enumerable keys.
 *
 * Intended as the `equality` argument of `useSelector` when the selector
 * builds a fresh object/array on every call (e.g. `(s) => ({ a: s.a })`).
 */
export const shallowEqual = (a: unknown, b: unknown): boolean => {
  if (Object.is(a, b)) {
    return true;
  }
  if (
    typeof a !== "object" ||
    a === null ||
    typeof b !== "object" ||
    b === null
  ) {
    return false;
  }
  const keysA = Object.keys(a);
  const keysB = Object.keys(b);
  if (keysA.length !== keysB.length) {
    return false;
  }
  for (const key of keysA) {
    if (
      !Object.hasOwn(b, key) ||
      !Object.is(
        (a as Record<string, unknown>)[key],
        (b as Record<string, unknown>)[key],
      )
    ) {
      return false;
    }
  }
  return true;
};