import { ILogger } from './types';
/**
 * Options for configuring the InMemoryCache instance.
 */
export interface CacheOptions {
    /**
     * Logger instance for warnings. If not provided, no warnings will be logged.
     */
    logger?: ILogger;
}
/**
 * In-memory cache with TTL expiration and automatic cleanup.
 *
 * Uses a wrapper object `{ hit: true, value: T }` pattern internally
 * to correctly handle falsy values (false, 0, '', null).
 */
export declare class InMemoryCache {
    private readonly store;
    private readonly ttlMs;
    private readonly logger?;
    private cleanupTimer;
    constructor(ttlMs?: number, options?: CacheOptions);
    /**
     * Get a cached value. Returns `{ hit: true, value }` if found and not expired,
     * or `{ hit: false }` otherwise. This avoids ambiguity with falsy values.
     */
    get<T>(key: string): {
        hit: true;
        value: T;
    } | {
        hit: false;
    };
    /**
     * Check if a key exists AND is not expired.
     */
    has(key: string): boolean;
    set<T>(key: string, value: T): void;
    delete(key: string): boolean;
    clear(): void;
    getStats(): {
        size: number;
        keys: string[];
        enabled: boolean;
    };
    /**
     * Release the cleanup timer. Call this when the client is being disposed
     * to prevent memory leaks and dangling timers.
     * Idempotent: safe to call multiple times.
     */
    destroy(): void;
    private cleanup;
}