import { useMemo } from 'react';
import { useLocalStorage } from '@/hooks/useLocalStorage';
import {
  DEFAULT_NOTIFICATION_PREFS,
  NOTIFICATION_PREFS_KEY,
  type NotificationPrefs,
} from '@/lib/notificationPrefs';

/**
 * Read/write the device-local notification preferences.
 *
 * Returns a memoized object (stable identity until the stored value changes) so
 * callers can safely put it in effect dependency arrays — an object literal that
 * is fresh every render would otherwise re-run those effects on every render.
 * Missing keys fall back to the defaults, so adding a new category later does
 * not leave existing users with `undefined`.
 */
export function useNotificationPrefs() {
  const [stored, setPrefs] = useLocalStorage<NotificationPrefs>(
    NOTIFICATION_PREFS_KEY,
    DEFAULT_NOTIFICATION_PREFS,
  );

  const prefs = useMemo<NotificationPrefs>(
    () => ({ ...DEFAULT_NOTIFICATION_PREFS, ...(stored ?? {}) }),
    [stored],
  );

  return [prefs, setPrefs] as const;
}