import "server-only";

import { logger } from "@/lib/logger";
import { redis } from "@/lib/redis";

const DEFAULT_CACHE_TTL = 60;

function isRedisAvailable(): boolean {
	return !!redis && redis.status !== "end";
}

export async function cachedQuery<T>(
	cacheKey: string,
	queryFn: () => Promise<T>,
	ttl: number = DEFAULT_CACHE_TTL,
): Promise<T> {
	if (!isRedisAvailable()) {
		return queryFn();
	}

	try {
		const cached = await redis?.get(cacheKey);
		if (cached !== null && cached !== undefined) {
			return JSON.parse(cached) as T;
		}
	} catch (err) {
		logger.warn("[cache] read failed, falling back to DB", {
			key: cacheKey,
			error: String(err),
		});
	}

	const result = await queryFn();

	try {
		await redis?.setex(cacheKey, ttl, JSON.stringify(result));
	} catch (err) {
		logger.warn("[cache] write failed, continuing without cache", {
			key: cacheKey,
			error: String(err),
		});
	}

	return result;
}

/** Invalidate cache keys matching a glob pattern. */
export async function invalidateCache(pattern: string): Promise<number> {
	if (!isRedisAvailable()) return 0;
	const r = redis;
	if (!r) return 0;
	const keys = await r.keys(pattern);
	return keys.length > 0 ? r.del(...keys) : 0;
}

/** Invalidate a single cache key immediately. */
export async function invalidateKey(key: string): Promise<number> {
	if (!isRedisAvailable()) return 0;
	if (!redis) return 0;
	return redis.del(key);
}