// credit: https://github.com/facebook/fbjs/blob/main/packages/fbjs/src/core/shallowEqual.js
export function shallowEqual(objA: any, objB: any) {
  if (Object.is(objA, objB)) {
    return true;
  }

  if (
    typeof objA !== 'object' ||
    objA === null ||
    typeof objB !== 'object' ||
    objB === null
  ) {
    return false;
  }

  const keysA = Object.keys(objA);
  const keysB = Object.keys(objB);

  if (keysA.length !== keysB.length) {
    return false;
  }

  // Test for A's keys different from B.
  for (const key of keysA) {
    if (
      !Object.prototype.hasOwnProperty.call(objB, key) ||
      !Object.is(objA[key], objB[key])
    ) {
      return false;
    }
  }

  return true;
}

export const shallowUpdater =
  <T>(newState: T) =>
  (state: T | null): T => {
    if (state && shallowEqual(state, newState)) {
      return state;
    }
    return newState;
  };