import Redis from 'ioredis';
import { logger } from '../utils/logger.js';

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

    static getInstance() {
        if (!RedisClient.instance) {
            RedisClient.instance = new RedisClient();
        }
        return RedisClient.instance;
    }

    async connect() {
        const config = {
            host: process.env.REDIS_HOST || 'localhost',
            port: process.env.REDIS_PORT || 6379,
            password: process.env.REDIS_PASSWORD || undefined,
            db: parseInt(process.env.REDIS_DB) || 2, // Different DB for safety guard
            retryStrategy: (times) => {
                const delay = Math.min(times * 50, 2000);
                return delay;
            },
            enableOfflineQueue: false
        };

        try {
            this.client = new Redis(config);

            this.client.on('connect', () => {
                logger.info('Redis connection established');
            });

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

            this.client.on('close', () => {
                logger.warn('Redis connection closed');
            });

            // Wait for connection
            await this.client.ping();
            
            return this.client;
        } catch (error) {
            logger.error('Failed to connect to Redis:', error);
            throw error;
        }
    }

    async checkHealth() {
        try {
            const result = await this.client.ping();
            return result === 'PONG';
        } catch (error) {
            logger.error('Redis health check failed:', error);
            return false;
        }
    }

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

    // Cache methods with JSON serialization
    async setWithExpiry(key, value, ttl) {
        return await this.client.setex(key, ttl, JSON.stringify(value));
    }

    async get(key) {
        const value = await this.client.get(key);
        return value ? JSON.parse(value) : null;
    }

    async del(key) {
        return await this.client.del(key);
    }

    async exists(key) {
        return await this.client.exists(key);
    }

    // Hash operations
    async hset(key, field, value) {
        return await this.client.hset(key, field, JSON.stringify(value));
    }

    async hget(key, field) {
        const value = await this.client.hget(key, field);
        return value ? JSON.parse(value) : null;
    }

    async hdel(key, field) {
        return await this.client.hdel(key, field);
    }

    async hgetall(key) {
        const data = await this.client.hgetall(key);
        const result = {};
        for (const [field, value] of Object.entries(data)) {
            result[field] = JSON.parse(value);
        }
        return result;
    }

    // List operations  
    async lpush(key, value) {
        return await this.client.lpush(key, JSON.stringify(value));
    }

    async rpush(key, value) {
        return await this.client.rpush(key, JSON.stringify(value));
    }

    async lrange(key, start, stop) {
        const items = await this.client.lrange(key, start, stop);
        return items.map(item => JSON.parse(item));
    }

    async ltrim(key, start, stop) {
        return await this.client.ltrim(key, start, stop);
    }

    // Set operations
    async sadd(key, member) {
        return await this.client.sadd(key, JSON.stringify(member));
    }

    async srem(key, member) {
        return await this.client.srem(key, JSON.stringify(member));
    }

    async smembers(key) {
        const members = await this.client.smembers(key);
        return members.map(member => JSON.parse(member));
    }

    async sismember(key, member) {
        return await this.client.sismember(key, JSON.stringify(member));
    }

    // Expiry operations
    async expire(key, seconds) {
        return await this.client.expire(key, seconds);
    }

    async ttl(key) {
        return await this.client.ttl(key);
    }
}