redis.service.ts

import { Injectable, OnModuleInit, OnModuleDestroy, Logger } from '@nestjs/common';
import { createClient, RedisClientType } from 'redis';

@Injectable()
export class RedisService implements OnModuleInit, OnModuleDestroy {
  private client: RedisClientType;
  private readonly logger = new Logger(RedisService.name);

  async onModuleInit() {
    try {
      this.client = createClient({
        url: process.env.REDIS_URL || 'redis://localhost:6379',
        socket: {
          reconnectStrategy: (retries) => Math.min(retries * 50, 1000),
        },
      });

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

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

      await this.client.connect();
    } catch (error) {
      this.logger.error('Failed to connect to Redis:', error);
    }
  }

  async onModuleDestroy() {
    if (this.client) {
      await this.client.quit();
      this.logger.log('Redis client disconnected');
    }
  }

  /**
   * Get value from cache
   */
  async get(key: string): Promise<string | null> {
    try {
      return await this.client.get(key);
    } catch (error) {
      this.logger.error(`Failed to get cache key ${key}:`, error);
      return null;
    }
  }

  /**
   * Set value in cache with TTL
   */
  async set(key: string, value: string, ttlSeconds: number): Promise<boolean> {
    try {
      await this.client.setEx(key, ttlSeconds, value);
      return true;
    } catch (error) {
      this.logger.error(`Failed to set cache key ${key}:`, error);
      return false;
    }
  }

  /**
   * Delete value from cache
   */
  async delete(key: string): Promise<boolean> {
    try {
      await this.client.del(key);
      return true;
    } catch (error) {
      this.logger.error(`Failed to delete cache key ${key}:`, error);
      return false;
    }
  }

  /**
   * Delete multiple keys
   */
  async deletePattern(pattern: string): Promise<number> {
    try {
      let count = 0;
      let cursor = 0;
      do {
        const reply = await this.client.scan(cursor, {
          MATCH: pattern,
          COUNT: 100,
        });
        cursor = reply.cursor;
        if (reply.keys.length > 0) {
          await this.client.del(reply.keys);
          count += reply.keys.length;
        }
      } while (cursor !== 0);
      return count;
    } catch (error) {
      this.logger.error(`Failed to delete pattern ${pattern}:`, error);
      return 0;
    }
  }

  /**
   * Get Redis client for advanced operations
   */
  getClient(): RedisClientType {
    return this.client;
  }
}