export type NotificationScope = 'photos' | 'guests' | 'gallery' | 'events' | 'package' | 'general';

export type ScopedNotification = {
  scope: NotificationScope;
  is_read?: boolean;
};

export type NotificationGroup<T extends ScopedNotification> = {
  scope: NotificationScope;
  items: T[];
  unread: number;
};

const SCOPE_ORDER: NotificationScope[] = [
  'photos',
  'guests',
  'gallery',
  'events',
  'package',
  'general',
];

export function groupNotificationsByScope<T extends ScopedNotification>(items: T[]): NotificationGroup<T>[] {
  const groups = new Map<NotificationScope, NotificationGroup<T>>();

  items.forEach((item) => {
    const scope = item.scope ?? 'general';
    const existing = groups.get(scope);
    if (existing) {
      existing.items.push(item);
      if (!item.is_read) {
        existing.unread += 1;
      }
      return;
    }

    groups.set(scope, {
      scope,
      items: [item],
      unread: item.is_read ? 0 : 1,
    });
  });

  return Array.from(groups.values()).sort((a, b) => {
    const aIndex = SCOPE_ORDER.indexOf(a.scope);
    const bIndex = SCOPE_ORDER.indexOf(b.scope);
    return aIndex - bIndex;
  });
}