import Redis from 'ioredis';
import logger from '@server/logger';

interface RedisConfig {
  host: string;
  port: number;
  password?: string;
  db?: number;
  retryDelayOnFailover?: number;
  maxRetriesPerRequest?: number;
}

class RedisManager {
  private static instance: RedisManager;
  private client: Redis | null = null;
  private subscriber: Redis | null = null;
  private publisher: Redis | null = null;
  private isEnabled: boolean = false;
  private subscribers: Map<string, Set<(channel: string, message: string) => void>> = new Map();

  private constructor() {
    this.isEnabled = !!process.env.REDIS;
    if (this.isEnabled) {
      this.initializeClients();
    }
  }

  public static getInstance(): RedisManager {
    if (!RedisManager.instance) {
      RedisManager.instance = new RedisManager();
    }
    return RedisManager.instance;
  }

  private getRedisConfig(): RedisConfig {
    return {
      host: process.env.REDIS_HOST || 'localhost',
      port: parseInt(process.env.REDIS_PORT || '6379'),
      password: process.env.REDIS_PASSWORD,
      db: parseInt(process.env.REDIS_DB || '0'),
      retryDelayOnFailover: 100,
      maxRetriesPerRequest: 3,
    };
  }

  private initializeClients(): void {
    const config = this.getRedisConfig();

    try {
      // Main client for general operations
      this.client = new Redis(config);
      
      // Dedicated publisher client
      this.publisher = new Redis(config);
      
      // Dedicated subscriber client
      this.subscriber = new Redis(config);

      // Set up error handlers
      this.client.on('error', (err) => {
        logger.error('Redis client error:', err);
      });

      this.publisher.on('error', (err) => {
        logger.error('Redis publisher error:', err);
      });

      this.subscriber.on('error', (err) => {
        logger.error('Redis subscriber error:', err);
      });

      // Set up connection handlers
      this.client.on('connect', () => {
        logger.info('Redis client connected');
      });

      this.publisher.on('connect', () => {
        logger.info('Redis publisher connected');
      });

      this.subscriber.on('connect', () => {
        logger.info('Redis subscriber connected');
      });

      // Set up message handler for subscriber
      this.subscriber.on('message', (channel: string, message: string) => {
        const channelSubscribers = this.subscribers.get(channel);
        if (channelSubscribers) {
          channelSubscribers.forEach(callback => {
            try {
              callback(channel, message);
            } catch (error) {
              logger.error(`Error in subscriber callback for channel ${channel}:`, error);
            }
          });
        }
      });

      logger.info('Redis clients initialized successfully');
    } catch (error) {
      logger.error('Failed to initialize Redis clients:', error);
      this.isEnabled = false;
    }
  }

  public isRedisEnabled(): boolean {
    return this.isEnabled && this.client !== null;
  }

  public getClient(): Redis | null {
    return this.client;
  }

  public async set(key: string, value: string, ttl?: number): Promise<boolean> {
    if (!this.isRedisEnabled() || !this.client) return false;
    
    try {
      if (ttl) {
        await this.client.setex(key, ttl, value);
      } else {
        await this.client.set(key, value);
      }
      return true;
    } catch (error) {
      logger.error('Redis SET error:', error);
      return false;
    }
  }

  public async get(key: string): Promise<string | null> {
    if (!this.isRedisEnabled() || !this.client) return null;
    
    try {
      return await this.client.get(key);
    } catch (error) {
      logger.error('Redis GET error:', error);
      return null;
    }
  }

  public async del(key: string): Promise<boolean> {
    if (!this.isRedisEnabled() || !this.client) return false;
    
    try {
      await this.client.del(key);
      return true;
    } catch (error) {
      logger.error('Redis DEL error:', error);
      return false;
    }
  }

  public async sadd(key: string, member: string): Promise<boolean> {
    if (!this.isRedisEnabled() || !this.client) return false;
    
    try {
      await this.client.sadd(key, member);
      return true;
    } catch (error) {
      logger.error('Redis SADD error:', error);
      return false;
    }
  }

  public async srem(key: string, member: string): Promise<boolean> {
    if (!this.isRedisEnabled() || !this.client) return false;
    
    try {
      await this.client.srem(key, member);
      return true;
    } catch (error) {
      logger.error('Redis SREM error:', error);
      return false;
    }
  }

  public async smembers(key: string): Promise<string[]> {
    if (!this.isRedisEnabled() || !this.client) return [];
    
    try {
      return await this.client.smembers(key);
    } catch (error) {
      logger.error('Redis SMEMBERS error:', error);
      return [];
    }
  }

  public async hset(key: string, field: string, value: string): Promise<boolean> {
    if (!this.isRedisEnabled() || !this.client) return false;
    
    try {
      await this.client.hset(key, field, value);
      return true;
    } catch (error) {
      logger.error('Redis HSET error:', error);
      return false;
    }
  }

  public async hget(key: string, field: string): Promise<string | null> {
    if (!this.isRedisEnabled() || !this.client) return null;
    
    try {
      return await this.client.hget(key, field);
    } catch (error) {
      logger.error('Redis HGET error:', error);
      return null;
    }
  }

  public async hdel(key: string, field: string): Promise<boolean> {
    if (!this.isRedisEnabled() || !this.client) return false;
    
    try {
      await this.client.hdel(key, field);
      return true;
    } catch (error) {
      logger.error('Redis HDEL error:', error);
      return false;
    }
  }

  public async hgetall(key: string): Promise<Record<string, string>> {
    if (!this.isRedisEnabled() || !this.client) return {};
    
    try {
      return await this.client.hgetall(key);
    } catch (error) {
      logger.error('Redis HGETALL error:', error);
      return {};
    }
  }

  public async publish(channel: string, message: string): Promise<boolean> {
    if (!this.isRedisEnabled() || !this.publisher) return false;
    
    try {
      await this.publisher.publish(channel, message);
      return true;
    } catch (error) {
      logger.error('Redis PUBLISH error:', error);
      return false;
    }
  }

  public async subscribe(channel: string, callback: (channel: string, message: string) => void): Promise<boolean> {
    if (!this.isRedisEnabled() || !this.subscriber) return false;
    
    try {
      // Add callback to subscribers map
      if (!this.subscribers.has(channel)) {
        this.subscribers.set(channel, new Set());
        // Only subscribe to the channel if it's the first subscriber
        await this.subscriber.subscribe(channel);
      }
      
      this.subscribers.get(channel)!.add(callback);
      return true;
    } catch (error) {
      logger.error('Redis SUBSCRIBE error:', error);
      return false;
    }
  }

  public async unsubscribe(channel: string, callback?: (channel: string, message: string) => void): Promise<boolean> {
    if (!this.isRedisEnabled() || !this.subscriber) return false;
    
    try {
      const channelSubscribers = this.subscribers.get(channel);
      if (!channelSubscribers) return true;

      if (callback) {
        // Remove specific callback
        channelSubscribers.delete(callback);
        if (channelSubscribers.size === 0) {
          this.subscribers.delete(channel);
          await this.subscriber.unsubscribe(channel);
        }
      } else {
        // Remove all callbacks for this channel
        this.subscribers.delete(channel);
        await this.subscriber.unsubscribe(channel);
      }
      
      return true;
    } catch (error) {
      logger.error('Redis UNSUBSCRIBE error:', error);
      return false;
    }
  }

  public async disconnect(): Promise<void> {
    try {
      if (this.client) {
        await this.client.quit();
        this.client = null;
      }
      if (this.publisher) {
        await this.publisher.quit();
        this.publisher = null;
      }
      if (this.subscriber) {
        await this.subscriber.quit();
        this.subscriber = null;
      }
      this.subscribers.clear();
      logger.info('Redis clients disconnected');
    } catch (error) {
      logger.error('Error disconnecting Redis clients:', error);
    }
  }
}

// Export singleton instance
export const redisManager = RedisManager.getInstance();
export default redisManager;