/**
 * LRU Cache implementation with TTL support
 * Used for caching metadata extraction results
 *
 * @example
 * ```typescript
 * import { metadataCache, stopCacheCleanup, startCacheCleanup } from './cache';
 *
 * // For graceful server shutdown
 * process.on('SIGTERM', () => {
 *   stopCacheCleanup();
 *   // ... other cleanup
 * });
 *
 * // For testing environments
 * afterAll(() => {
 *   stopCacheCleanup();
 * });
 *
 * // Custom cleanup interval (5 minutes)
 * stopCacheCleanup();
 * startCacheCleanup(5 * 60 * 1000);
 * ```
 */
export declare class LRUCache<T> {
    private cache;
    private maxSize;
    private defaultTTL;
    constructor(maxSize?: number, defaultTTL?: number);
    set(key: string, value: T, ttl?: number): void;
    get(key: string): T | undefined;
    has(key: string): boolean;
    delete(key: string): boolean;
    clear(): void;
    size(): number;
    cleanup(): number;
    getStats(): {
        size: number;
        maxSize: number;
        defaultTTL: number;
    };
}
import { ExtractedMetadata, GeneratedPreview } from '../types';
export declare const metadataCache: LRUCache<ExtractedMetadata>;
export declare const previewCache: LRUCache<GeneratedPreview>;
/**
 * Starts automatic cache cleanup if not already running.
 * @param intervalMs - Cleanup interval in milliseconds (default: 10 minutes)
 */
export declare function startCacheCleanup(intervalMs?: number): void;
/**
 * Stops the automatic cache cleanup interval.
 * Useful for graceful shutdown in applications and testing environments.
 */
export declare function stopCacheCleanup(): void;
/**
 * Checks if automatic cache cleanup is currently running.
 * @returns true if cleanup interval is active
 */
export declare function isCacheCleanupRunning(): boolean;