import { CacheStrategy } from '../types';
/**
 * File-system-based cache implementation.
 *
 * Each entry is stored as a JSON file in the specified directory.
 * Expired entries are automatically deleted when accessed.
 *
 * @example
 * ```typescript
 * import { fetchTranscript, FsCache } from 'youtube-transcript-plus';
 * const transcript = await fetchTranscript('dQw4w9WgXcQ', {
 *   cache: new FsCache('./my-cache-dir', 86400000), // 1 day TTL
 * });
 * ```
 */
export declare class FsCache implements CacheStrategy {
    private cacheDir;
    private defaultTTL;
    private ready;
    /**
     * @param cacheDir - Directory to store cache files. Created automatically if it doesn't exist.
     * @param defaultTTL - Default time-to-live in milliseconds. Defaults to 1 hour.
     */
    constructor(cacheDir?: string, defaultTTL?: number);
    get(key: string): Promise<string | null>;
    set(key: string, value: string, ttl?: number): Promise<void>;
}