/**
 * Redis client singleton for SentryAgent.ai AgentIdP.
 * Used for token revocation tracking, rate limiting, and monthly token counts.
 */

import { createClient, RedisClientType } from 'redis';

let redisClient: RedisClientType | null = null;

/**
 * Returns the singleton Redis client instance.
 * Initialises and connects the client on first call using REDIS_URL from env.
 *
 * @returns Promise resolving to the connected Redis client.
 * @throws Error if REDIS_URL is not set or connection fails.
 */
export async function getRedisClient(): Promise<RedisClientType> {
  if (!redisClient) {
    const url = process.env['REDIS_URL'];
    if (!url) {
      throw new Error('REDIS_URL environment variable is required');
    }

    redisClient = createClient({ url }) as RedisClientType;

    redisClient.on('error', (err: Error) => {
      // eslint-disable-next-line no-console
      console.error('Redis client error', err);
    });

    await redisClient.connect();
  }
  return redisClient;
}

/**
 * Disconnects the Redis client and resets the singleton.
 * Used for graceful shutdown and tests.
 *
 * @returns Promise that resolves when the client is disconnected.
 */
export async function closeRedisClient(): Promise<void> {
  if (redisClient) {
    await redisClient.quit();
    redisClient = null;
  }
}