import { createSharedStore, type SharedStore } from "@hivegrid/shared-store";

/**
 * Singleton SharedStore for the web process. Tenant-scoped caches,
 * cross-replica rate limits, and MFA challenge state migrated as part
 * of task #38 all use this instance so a single Redis connection is
 * reused across the web lifetime.
 */
let cachedStore: SharedStore | null = null;
let crossAppCacheStore: SharedStore | null = null;
let factory: () => SharedStore = () => createSharedStore({ namespace: "web", redisUrl: process.env.REDIS_URL });

export function getSharedStore(): SharedStore {
  if (cachedStore === null) {
    cachedStore = factory();
  }
  return cachedStore;
}

/** Shared cache-invalidation namespace used by both the API and web apps. */
export function getCrossAppCacheStore(): SharedStore {
  if (crossAppCacheStore === null) {
    crossAppCacheStore = createSharedStore({ namespace: "cross-app-cache", adapter: getSharedStore().adapter });
  }
  return crossAppCacheStore;
}

/** Close the singleton adapter for short-lived processes such as DB seeding. */
export async function closeSharedStores(): Promise<void> {
  const stores = [cachedStore, crossAppCacheStore].filter((store): store is SharedStore => store !== null);
  cachedStore = null;
  crossAppCacheStore = null;

  const seenAdapters = new Set<SharedStore["adapter"]>();
  await Promise.all(
    stores.map(async (store) => {
      if (seenAdapters.has(store.adapter)) return;
      seenAdapters.add(store.adapter);
      await store.close();
    }),
  );
}

export function __setSharedStoreFactoryForTests(next: () => SharedStore): void {
  factory = next;
  cachedStore = null;
  crossAppCacheStore = null;
}

export function __resetSharedStoreForTests(): void {
  factory = () => createSharedStore({ namespace: "web", redisUrl: process.env.REDIS_URL });
  cachedStore = null;
  crossAppCacheStore = null;
}