All files / src/lib/cache cache-service.ts

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import NodeCache from 'node-cache';

interface CacheOptions {
  /** Default TTL in seconds */
  ttl?: number;
  /** Check period for expired keys in seconds */
  checkperiod?: number;
}

interface CacheStats {
  hits: number;
  misses: number;
  keys: number;
  ksize: number;
  vsize: number;
  hitRate: number;
}

/**
 * In-memory cache service using node-cache
 * Provides caching for database queries and computed values
 */
class CacheService {
  private cache: NodeCache;
  private enabled: boolean;

  constructor(options: CacheOptions = {}) {
    this.cache = new NodeCache({
      stdTTL: options.ttl || 300, // 5 minutes default
      checkperiod: options.checkperiod || 60,
      useClones: false, // Better performance, but be careful with mutations
    });

    // Can be disabled via environment variable
    this.enabled = process.env.DISABLE_CACHE !== 'true';
  }

  /**
   * Get a value from cache
   */
  get<T>(key: string): T | undefined {
    if (!this.enabled) return undefined;
    return this.cache.get<T>(key);
  }

  /**
   * Set a value in cache
   */
  set<T>(key: string, value: T, ttl?: number): boolean {
    if (!this.enabled) return false;
    if (ttl !== undefined) {
      return this.cache.set(key, value, ttl);
    }
    return this.cache.set(key, value);
  }

  /**
   * Get a value from cache, or set it using the fetcher function
   * This is the primary method for caching database queries
   */
  async getOrSet<T>(
    key: string,
    fetcher: () => Promise<T>,
    ttl?: number
  ): Promise<T> {
    if (!this.enabled) {
      return fetcher();
    }

    const cached = this.get<T>(key);
    if (cached !== undefined) {
      return cached;
    }

    const value = await fetcher();
    this.set(key, value, ttl);
    return value;
  }

  /**
   * Check if a key exists in cache
   */
  has(key: string): boolean {
    return this.cache.has(key);
  }

  /**
   * Delete a specific key from cache
   */
  delete(key: string): number {
    return this.cache.del(key);
  }

  /**
   * Delete multiple keys from cache
   */
  deleteMany(keys: string[]): number {
    return this.cache.del(keys);
  }

  /**
   * Delete all keys matching a pattern (regex)
   */
  deletePattern(pattern: string): number {
    const keys = this.cache.keys();
    const regex = new RegExp(pattern);
    const matchingKeys = keys.filter(key => regex.test(key));
    return this.cache.del(matchingKeys);
  }

  /**
   * Clear all cached data
   */
  flush(): void {
    this.cache.flushAll();
  }

  /**
   * Get all cached keys
   */
  keys(): string[] {
    return this.cache.keys();
  }

  /**
   * Get cache statistics
   */
  getStats(): CacheStats {
    const stats = this.cache.getStats();
    const total = stats.hits + stats.misses;
    return {
      hits: stats.hits,
      misses: stats.misses,
      keys: stats.keys,
      ksize: stats.ksize,
      vsize: stats.vsize,
      hitRate: total > 0 ? stats.hits / total : 0,
    };
  }

  /**
   * Get remaining TTL for a key in seconds
   */
  getTtl(key: string): number | undefined {
    return this.cache.getTtl(key);
  }

  /**
   * Enable or disable caching at runtime
   */
  setEnabled(enabled: boolean): void {
    this.enabled = enabled;
  }

  /**
   * Check if caching is enabled
   */
  isEnabled(): boolean {
    return this.enabled;
  }
}

// Singleton instance
const globalForCache = globalThis as unknown as { cacheService: CacheService };

export const cacheService = globalForCache.cacheService || new CacheService();

if (process.env.NODE_ENV !== 'production') {
  globalForCache.cacheService = cacheService;
}

export { CacheService };
export type { CacheOptions, CacheStats };