import type { Storage } from 'unstorage';
import type { Cache as CacheInterface } from '../cache';
export declare class UnstorageCache implements CacheInterface {
    /**
     * The underlying Unstorage storage instance.
     */
    storage: Storage;
    /**
     * Key prefix used for namespacing cache entries.
     */
    prefix: string;
    /**
     * Creates a new UnstorageCache instance.
     *
     * @param storage The Unstorage storage instance.
     * @param prefix Optional key prefix for namespacing. Defaults to an empty string.
     */
    constructor(storage: Storage, prefix?: string);
    /**
     * Retrieves a cached value by key.
     *
     * @param key The cache key.
     * @returns The cached value or null if not found.
     */
    get(key: string): Promise<any | null>;
    /**
     * Checks if a key exists in the cache.
     *
     * @param key The cache key.
     * @returns True if the key exists, false otherwise.
     */
    has(key: string): Promise<boolean>;
    /**
     * Purges cache entries associated with the given tags.
     *
     * @param tags An array of tags to purge.
     */
    purgeTags(tags: string[]): Promise<void>;
    /**
     * Purges cache entries associated with a specific tag.
     *
     * @param tag The tag to purge.
     */
    purgeTag(tag: string): Promise<void>;
    /**
     * Purges cache entries by their keys.
     *
     * @param keys An array of keys to purge.
     */
    purgeKeys(keys: string[]): Promise<void>;
    /**
     * Purges all cache entries.
     */
    purgeAll(): Promise<void>;
    /**
     * Sets a value in the cache.
     *
     * @param key The cache key.
     * @param value The value to cache.
     * @param ttl Time-to-live in milliseconds.
     * @param tags Optional tags to associate with the cache entry.
     */
    set(key: string, value: any, ttl: number, tags?: string[]): Promise<void>;
    /**
     * Adds a key to a tag's list of associated keys.
     *
     * @param tag The tag.
     * @param key The key to add.
     * @private
     */
    private addKeyToTag;
    /**
     * Generates a namespaced key.
     *
     * @param key The key to namespace.
     * @returns The namespaced key.
     * @private
     */
    private getKey;
}