/**
 * TTL Validation Utilities
 *
 * Helper functions for validating and normalizing TTL values.
 */
/**
 * Maximum TTL in seconds (roughly 100 years).
 * Prevents integer overflow issues.
 */
export declare const MAX_TTL_SECONDS = 3153600000;
/**
 * Validate a TTL value.
 *
 * @param ttlSeconds - TTL in seconds
 * @throws StorageTTLError if TTL is invalid
 */
export declare function validateTTL(ttlSeconds: number): void;
/**
 * Validate TTL if provided (optional TTL).
 *
 * @param ttlSeconds - Optional TTL in seconds
 * @throws StorageTTLError if TTL is provided but invalid
 */
export declare function validateOptionalTTL(ttlSeconds: number | undefined): void;
/**
 * Calculate expiration timestamp from TTL.
 *
 * @param ttlSeconds - TTL in seconds
 * @returns Expiration timestamp (Date.now() + ttlSeconds * 1000)
 */
export declare function ttlToExpiresAt(ttlSeconds: number): number;
/**
 * Calculate remaining TTL from expiration timestamp.
 *
 * @param expiresAt - Expiration timestamp
 * @returns Remaining seconds, or 0 if expired
 */
export declare function expiresAtToTTL(expiresAt: number): number;
/**
 * Check if an expiration timestamp has passed.
 *
 * @param expiresAt - Expiration timestamp
 * @returns true if expired (current time >= expiresAt)
 */
export declare function isExpired(expiresAt: number | undefined): boolean;
/**
 * Normalize TTL to seconds if provided in milliseconds.
 * Useful for adapting from APIs that use milliseconds.
 *
 * @param ttl - TTL value
 * @param unit - 'seconds' or 'milliseconds'
 * @returns TTL in seconds
 */
export declare function normalizeTTL(ttl: number, unit: 'seconds' | 'milliseconds'): number;