import { QueryCache, QueryClient } from "@tanstack/react-query";

/**
 * Global query-error notifier. AlertContext registers its `error()` toast
 * here on mount; until then failures fall back to console.error.
 */
let queryErrorNotifier: ((msg: string) => void) | null = null;

export function registerQueryErrorNotifier(fn: (msg: string) => void) {
  queryErrorNotifier = fn;
}

/** Rate limit: at most one query-error toast per window (a page can have many failing queries). */
const ERROR_TOAST_WINDOW_MS = 4000;
let lastErrorToastAt = 0;

export const queryClient = new QueryClient({
  queryCache: new QueryCache({
    onError: (error, query) => {
      // Pages with bespoke error handling (detail pages that toast + navigate,
      // purely-local queries like QR generation) opt out via query meta.
      if (query.meta?.suppressGlobalErrorToast) return;
      // Background refetch failure with stale data still on screen — stay silent.
      if (query.state.data !== undefined) return;
      // 401s are handled by apiFetch/AuthContext (token refresh / logout).
      if (error instanceof Error && error.message === "Unauthorized") return;
      const now = Date.now();
      if (now - lastErrorToastAt < ERROR_TOAST_WINDOW_MS) return;
      lastErrorToastAt = now;
      if (queryErrorNotifier) {
        queryErrorNotifier("Nepodařilo se načíst data ze serveru");
      } else {
        console.error("Query failed before alert notifier registered:", error);
      }
    },
  }),
  defaultOptions: {
    queries: {
      staleTime: 30_000,
      gcTime: 5 * 60_000,
      refetchOnWindowFocus: true,
      retry: 1,
      refetchOnReconnect: true,
    },
  },
});