import {
  useInfiniteQuery,
  useMutation,
  useQuery,
  useQueryClient,
} from "@tanstack/react-query";

import { notificationsApi } from "./notificationsApi";

export const NOTIFICATIONS_KEY = ["notifications"] as const;
export const UNREAD_KEY = ["notifications", "unread"] as const;

const PAGE_SIZE = 20;

/**
 * Paginated (infinite) notifications for one read-state. Drives a drawer
 * section; call `fetchNextPage` as the user scrolls. Each page carries the
 * server `count` so we know when to stop.
 */
export function useInfiniteNotifications(isRead: boolean, enabled = true) {
  return useInfiniteQuery({
    queryKey: [...NOTIFICATIONS_KEY, "list", { isRead }],
    queryFn: ({ pageParam }) =>
      notificationsApi.list({ page: pageParam, limit: PAGE_SIZE, isRead }),
    initialPageParam: 1,
    getNextPageParam: (lastPage, allPages) => {
      const loaded = allPages.reduce((sum, p) => sum + p.items.length, 0);
      return loaded < lastPage.count ? allPages.length + 1 : undefined;
    },
    enabled,
  });
}

export function useUnreadCount(enabled = true) {
  return useQuery({
    queryKey: UNREAD_KEY,
    queryFn: () => notificationsApi.unreadCount(),
    enabled,
    // WebSocket keeps this fresh; poll as a fallback if the socket drops.
    refetchInterval: 60_000,
  });
}

export function useMarkRead() {
  const qc = useQueryClient();
  return useMutation({
    mutationFn: (id: string) => notificationsApi.markRead(id),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: NOTIFICATIONS_KEY });
      qc.invalidateQueries({ queryKey: UNREAD_KEY });
    },
  });
}

export function useMarkAllRead() {
  const qc = useQueryClient();
  return useMutation({
    mutationFn: () => notificationsApi.markAllRead(),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: NOTIFICATIONS_KEY });
      qc.invalidateQueries({ queryKey: UNREAD_KEY });
    },
  });
}