/**
 * API Response Caching Layer
 *
 * Implements HTTP caching for API responses
 */
interface CacheOptions {
    ttl?: number;
    staleWhileRevalidate?: number;
    tags?: string[];
    vary?: string[];
    private?: boolean;
    noStore?: boolean;
}
/**
 * Generate cache key from request
 */
export declare function generateCacheKey(request: Request): string;
/**
 * Get cached response
 */
export declare function getCachedResponse(request: Request): Promise<Response | null>;
/**
 * Set cached response
 */
export declare function setCachedResponse(request: Request, response: Response, options?: CacheOptions): Promise<void>;
/**
 * Invalidate cache by key
 */
export declare function invalidateCacheKey(key: string): void;
/**
 * Invalidate cache by pattern
 */
export declare function invalidateCachePattern(pattern: string): number;
/**
 * Invalidate cache by tags
 */
export declare function invalidateCacheTags(tags: string[]): number;
/**
 * Clear all cache
 */
export declare function clearCache(): void;
/**
 * Set Cache-Control headers
 */
export declare function setCacheHeaders(response: Response, options: CacheOptions): Response;
/**
 * Create caching middleware
 */
export declare function createCacheMiddleware(options?: CacheOptions): (request: Request, next: () => Promise<Response>) => Promise<Response>;
/**
 * Get cache statistics
 */
export declare function getCacheStats(): {
    totalEntries: number;
    validEntries: number;
    expiredEntries: number;
    totalSize: number;
    averageSize: number;
};
/**
 * Purge expired entries
 */
export declare function purgeExpiredCache(): number;
/**
 * Start cache cleanup interval
 */
export declare function startCacheCleanup(intervalMs?: number): NodeJS.Timeout;
/**
 * Cache response with ETag
 */
export declare function withETag(response: Response, content: string): Response;
/**
 * Check if request has matching ETag
 */
export declare function checkETag(request: Request, etag: string): boolean;
/**
 * Create 304 Not Modified response
 */
export declare function createNotModifiedResponse(): Response;
/**
 * Cache presets for common scenarios
 */
export declare const CACHE_PRESETS: {
    readonly noCache: {
        readonly noStore: true;
    };
    readonly short: {
        readonly ttl: 60;
        readonly staleWhileRevalidate: 30;
    };
    readonly medium: {
        readonly ttl: 300;
        readonly staleWhileRevalidate: 60;
    };
    readonly long: {
        readonly ttl: 3600;
        readonly staleWhileRevalidate: 300;
    };
    readonly veryLong: {
        readonly ttl: 86400;
        readonly staleWhileRevalidate: 3600;
    };
    readonly immutable: {
        readonly ttl: 31536000;
        readonly private: false;
    };
    readonly private: {
        readonly ttl: 300;
        readonly private: true;
    };
    readonly public: {
        readonly ttl: 3600;
        readonly private: false;
    };
};
/**
 * Cache API response
 */
export declare function cacheAPIResponse<T>(key: string, responseFn: () => Promise<T>, options?: CacheOptions): Promise<{
    data: T;
    cached: boolean;
}>;
export {};
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