import redis from '../config/redis.js';
import { env } from '../config/env.js';
import { emitCacheEvent } from '../config/socket.js';
import logger from '../utils/logger.js';
import type { GetInfoResponse, CacheEntry } from '../types/index.js';

/**
 * Cache key prefix for Netflix content
 */
const CACHE_PREFIX = 'netflix:content:';

/**
 * Generate cache key from URL
 */
function getCacheKey(url: string): string {
  // Use URL hash or title ID as key
  const titleId = url.match(/\/title\/(\d+)/)?.[1] || url;
  return `${CACHE_PREFIX}${titleId}`;
}

/**
 * Cache Service for Redis operations
 * Handles caching with TTL support
 */
export class CacheService {
  /**
   * Get cached content by URL
   */
  static async get(url: string): Promise<GetInfoResponse | null> {
    const key = getCacheKey(url);

    try {
      const cached = await redis.get(key);

      if (!cached) {
        logger.debug('Cache miss', { url });
        return null;
      }

      logger.debug('Cache hit', { url });
      const entry: CacheEntry<GetInfoResponse> = JSON.parse(cached);
      return entry.data;
    } catch (error) {
      logger.error('Cache get error', {
        url,
        error: error instanceof Error ? error.message : 'Unknown error',
      });
      return null;
    }
  }

  /**
   * Set cache entry with TTL
   */
  static async set(url: string, data: GetInfoResponse): Promise<void> {
    const key = getCacheKey(url);
    const ttl = env.REDIS_TTL_SECONDS;

    const entry: CacheEntry<GetInfoResponse> = {
      data,
      cachedAt: Date.now(),
      ttl,
    };

    try {
      await redis.setex(key, ttl, JSON.stringify(entry));
      emitCacheEvent({
        action: 'written',
        key,
        ttlSeconds: ttl,
        occurredAt: new Date().toISOString(),
      });
      logger.debug('Cache set', { url, ttl });
    } catch (error) {
      logger.error('Cache set error', {
        url,
        error: error instanceof Error ? error.message : 'Unknown error',
      });
    }
  }

  /**
   * Delete cached content
   */
  static async delete(url: string): Promise<void> {
    const key = getCacheKey(url);

    try {
      await redis.del(key);
      emitCacheEvent({
        action: 'deleted',
        key,
        occurredAt: new Date().toISOString(),
      });
      logger.debug('Cache deleted', { url });
    } catch (error) {
      logger.error('Cache delete error', {
        url,
        error: error instanceof Error ? error.message : 'Unknown error',
      });
    }
  }

  /**
   * Check if cache exists
   */
  static async exists(url: string): Promise<boolean> {
    const key = getCacheKey(url);

    try {
      const result = await redis.exists(key);
      return result === 1;
    } catch (error) {
      logger.error('Cache exists check error', {
        url,
        error: error instanceof Error ? error.message : 'Unknown error',
      });
      return false;
    }
  }

  /**
   * Get cache TTL remaining
   */
  static async getTTL(url: string): Promise<number> {
    const key = getCacheKey(url);

    try {
      return await redis.ttl(key);
    } catch (error) {
      logger.error('Cache TTL check error', {
        url,
        error: error instanceof Error ? error.message : 'Unknown error',
      });
      return -1;
    }
  }

  /**
   * Clear all Netflix content cache
   */
  static async clearAll(): Promise<void> {
    try {
      const keys = await redis.keys(`${CACHE_PREFIX}*`);

      if (keys.length > 0) {
        await redis.del(...keys);
        emitCacheEvent({
          action: 'cleared',
          count: keys.length,
          occurredAt: new Date().toISOString(),
        });
        logger.info('Cache cleared', { count: keys.length });
      }
    } catch (error) {
      logger.error('Cache clear error', {
        error: error instanceof Error ? error.message : 'Unknown error',
      });
    }
  }
}

export default CacheService;