import { Dayjs } from 'dayjs';
/**
 * Get all days to display in a calendar month grid (including padding days from prev/next months)
 * @param month - The month to display
 * @param locale - Optional locale for week start day (e.g., 'en', 'nb', 'de')
 */
export declare function getCalendarDays(month: Dayjs, locale?: string): Dayjs[];
/**
 * Check if a date is within a given range (inclusive)
 * Uses dayjs isBetween plugin with '[]' for inclusive start and end
 * @see https://day.js.org/docs/en/plugin/is-between
 */
export declare function isDateInRange(date: Dayjs, startDate: Dayjs | null, endDate: Dayjs | null): boolean;
/**
 * Check if a date is outside the current display month
 */
export declare function isOutsideMonth(date: Dayjs, displayMonth: Dayjs): boolean;
/**
 * Check if a date is today
 * Note: Uses local timezone. Both the input date and current time are compared
 * using the user's local timezone, which is the expected behavior for calendar UIs.
 * @param date - The date to check
 * @param now - Optional current date for testing (defaults to dayjs())
 */
export declare function isToday(date: Dayjs, now?: Dayjs): boolean;
/**
 * Get an array of weekday names (short form)
 * @param locale - Optional locale for localized weekday names (e.g., 'en', 'nb', 'de')
 * @param baseDate - Optional base date for testing (defaults to dayjs())
 */
export declare function getWeekdayNames(locale?: string, baseDate?: Dayjs): string[];
/**
 * Get the week number for a given date
 */
export declare function getWeekNumber(date: Dayjs): number;
/**
 * Get all week numbers for days in a calendar month grid
 */
export declare function getWeekNumbers(days: Dayjs[]): number[];
/**
 * Check if two dates are the same day
 */
export declare function isSameDay(date1: Dayjs | null, date2: Dayjs | null): boolean;
/**
 * Format a date range for display
 * When one date is missing, shows the format placeholder for the missing date
 */
export declare function formatDateRange(startDate: Dayjs | null, endDate: Dayjs | null, format: string): string;