/**
 * Time Utilities
 *
 * Utility functions for time-related operations.
 */
/**
 * Check if current time is within quiet hours.
 *
 * @param quietHoursStart - Start time in HH:MM format
 * @param quietHoursEnd - End time in HH:MM format
 * @param timezone - Timezone string (default: 'UTC')
 * @returns true if currently in quiet hours
 *
 * @example
 * ```typescript
 * // Check if 22:00 - 08:00 quiet hours are active
 * const inQuietHours = isInQuietHours('22:00', '08:00', 'America/New_York');
 * ```
 */
export declare function isInQuietHours(quietHoursStart: string | null | undefined, quietHoursEnd: string | null | undefined, timezone?: string): boolean;
/**
 * Check if a campaign is expired based on start date and duration
 */
export declare function isCampaignExpired(startDate: Date | undefined, duration: number | undefined): boolean;
/**
 * Calculate remaining days for a campaign
 */
export declare function getCampaignDaysRemaining(startDate: Date | undefined, duration: number | undefined): number;
/** Time utilities namespace */
export declare const TimeUtils: {
    readonly isInQuietHours: typeof isInQuietHours;
    readonly isCampaignExpired: typeof isCampaignExpired;
    readonly getCampaignDaysRemaining: typeof getCampaignDaysRemaining;
};
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