import { listPacks } from "@/lib/apiaries/offline-pack";
import type { StoredPack } from "./db";
import { isNetworkError } from "@/lib/http/fetch-with-timeout";

/**
 * The server's answer - or, only when the network failed, what the user's
 * offline packs say. A server refusal (ApiError: 403, 404, 400 ...) is never
 * covered up with pack data: the server knows better than an old pack.
 * When the packs have nothing (`fromPacks` returns null) or cannot be read,
 * the network error is passed on, so the caller shows "not loaded".
 *
 * Queries built on this read local storage when offline: give them
 * `networkMode: "always"`, or a paused retry would hide the fallback.
 */
export async function withPackFallback<T>(
  fetcher: () => Promise<T>,
  fromPacks: (packs: StoredPack[]) => T | null,
  ownerUserId: string,
): Promise<T> {
  try {
    return await fetcher();
  } catch (error) {
    if (!isNetworkError(error)) {
      throw error;
    }
    const fallback = await listPacks(ownerUserId).then(fromPacks, () => null);
    if (fallback === null) {
      throw error;
    }
    return fallback;
  }
}