const Redis = require('ioredis');
const logger = require('../utils/logger');

class RedisClient {
  constructor() {
    this.client = null;
    this.subscriber = null;
  }

  async connect() {
    try {
      this.client = new Redis({
        host: process.env.REDIS_HOST || 'localhost',
        port: process.env.REDIS_PORT || 6379,
        password: process.env.REDIS_PASSWORD || undefined,
        retryDelayOnFailover: 100,
        maxRetriesPerRequest: 3,
        lazyConnect: true,
        keepAlive: 30000,
        family: 4,
        db: 0
      });

      this.subscriber = new Redis({
        host: process.env.REDIS_HOST || 'localhost',
        port: process.env.REDIS_PORT || 6379,
        password: process.env.REDIS_PASSWORD || undefined,
        retryDelayOnFailover: 100,
        maxRetriesPerRequest: 3,
        lazyConnect: true,
        keepAlive: 30000,
        family: 4,
        db: 0
      });

      // Test connection
      await this.client.ping();
      await this.subscriber.ping();
      
      logger.info('Redis connections established successfully');
    } catch (error) {
      logger.error('Redis connection failed:', error);
      throw error;
    }
  }

  async disconnect() {
    if (this.client) {
      await this.client.quit();
      logger.info('Redis client disconnected');
    }
    if (this.subscriber) {
      await this.subscriber.quit();
      logger.info('Redis subscriber disconnected');
    }
  }

  async set(key, value, ttl = null) {
    try {
      if (ttl) {
        await this.client.setex(key, ttl, JSON.stringify(value));
      } else {
        await this.client.set(key, JSON.stringify(value));
      }
    } catch (error) {
      logger.error('Redis set error:', error);
      throw error;
    }
  }

  async get(key) {
    try {
      const value = await this.client.get(key);
      return value ? JSON.parse(value) : null;
    } catch (error) {
      logger.error('Redis get error:', error);
      throw error;
    }
  }

  async del(key) {
    try {
      await this.client.del(key);
    } catch (error) {
      logger.error('Redis del error:', error);
      throw error;
    }
  }

  async exists(key) {
    try {
      return await this.client.exists(key);
    } catch (error) {
      logger.error('Redis exists error:', error);
      throw error;
    }
  }

  async expire(key, seconds) {
    try {
      await this.client.expire(key, seconds);
    } catch (error) {
      logger.error('Redis expire error:', error);
      throw error;
    }
  }

  async publish(channel, message) {
    try {
      await this.client.publish(channel, JSON.stringify(message));
    } catch (error) {
      logger.error('Redis publish error:', error);
      throw error;
    }
  }

  async subscribe(channel, callback) {
    try {
      await this.subscriber.subscribe(channel);
      this.subscriber.on('message', (chan, message) => {
        if (chan === channel) {
          callback(JSON.parse(message));
        }
      });
    } catch (error) {
      logger.error('Redis subscribe error:', error);
      throw error;
    }
  }

  async unsubscribe(channel) {
    try {
      await this.subscriber.unsubscribe(channel);
    } catch (error) {
      logger.error('Redis unsubscribe error:', error);
      throw error;
    }
  }

  async healthCheck() {
    try {
      await this.client.ping();
      return true;
    } catch (error) {
      logger.error('Redis health check failed:', error);
      return false;
    }
  }

  // Device data caching methods
  async cacheDeviceData(deviceId, data, ttl = 300) {
    const key = `device:${deviceId}:data`;
    await this.set(key, data, ttl);
  }

  async getDeviceData(deviceId) {
    const key = `device:${deviceId}:data`;
    return await this.get(key);
  }

  // Alert caching methods
  async cacheAlert(alertId, alert, ttl = 3600) {
    const key = `alert:${alertId}`;
    await this.set(key, alert, ttl);
  }

  async getAlert(alertId) {
    const key = `alert:${alertId}`;
    return await this.get(key);
  }

  // User session caching
  async cacheUserSession(userId, sessionData, ttl = 86400) {
    const key = `session:${userId}`;
    await this.set(key, sessionData, ttl);
  }

  async getUserSession(userId) {
    const key = `session:${userId}`;
    return await this.get(key);
  }

  async invalidateUserSession(userId) {
    const key = `session:${userId}`;
    await this.del(key);
  }
}

module.exports = new RedisClient();