/**
 * Parses the value from a DateField change event (YYYY-MM-DD string) to a Date at local midnight.
 * Use this when you need a Date from event.target.value to avoid timezone shifts that occur
 * with `new Date(value)` (which interprets the string as UTC).
 *
 * @param value - The string from event.target.value (e.g. "2025-03-07" or "")
 * @returns {Date | null} - Date at local midnight for the given day, or null if value is empty or invalid
 */
export declare function parseDateFieldValue(value: string): Date | null;
/**
 * Normalises a locale tag for use with `Intl.DateTimeFormat`.
 *
 * Filters out tags that are not real Intl locales (the empty string and i18next's `cimode`
 * key-debug pseudo-language, surfaced as "Developer" in `LanguageSelection`) and replaces them
 * with the browser locale. Region-qualified and bare-language Intl tags are returned unchanged
 * so that the caller (`useDateFieldLocale`, callers passing a manual `locale` prop, etc.) keeps
 * full control of the policy decision.
 *
 * Note: prior versions of this function additionally rewrote bare `"en"` to the browser locale
 * so that UK browsers would not see US-style dates when the Manager UI language was English.
 * That policy now lives in `useDateFieldLocale` (browser-first), so this function no longer
 * special-cases `"en"`.
 */
export declare function resolveDateFieldLocale(locale: string | undefined): string;
/**
 * Returns the locale-aligned placeholder shown in the DateField. Result is memoized per locale —
 * see `datePlaceholderByLocale` above.
 */
export declare function getDateFieldPlaceholder(locale: string): string;
/**
 * Formats a Date for display in the DateField while keeping event payloads canonical.
 */
export declare function formatDateFieldValueForLocale(value: Date, locale: string): string;
/**
 * Parses localized or quick-typed DateField input into a Date.
 * Supports canonical YYYY-MM-DD, locale-ordered quick typing (e.g. DDMMYYYY), and YYYYMMDD.
 */
export declare function parseDateFieldDisplayValue(value: string, locale: string): Date | null;
/**
 * Converts a YYYY-MM-DD string (e.g. from DateField) to an ISO string at UTC midnight for that calendar day.
 * Use this when storing or sending date-only values so that the calendar day is preserved regardless of
 * user timezone (unlike calling .toISOString() on a local-midnight Date, which shifts the day for UTC+).
 *
 * @param value - The string from event.target.value (e.g. "2025-03-07" or "")
 * @returns {string | null} - "YYYY-MM-DDT00:00:00.000Z" or null if value is empty or invalid
 */
export declare function toISODateStringUTC(value: string): string | null;
/**
 * Converts a Date (e.g. at local midnight) to an ISO string at UTC midnight for the same calendar day.
 * Use when sending a date-only value to an API that expects UTC midnight (e.g. booking date).
 *
 * @param date - A Date instance (typically local midnight from a date picker)
 * @returns {string} "YYYY-MM-DDT00:00:00.000Z" for that calendar day
 */
export declare function dateToISODateUTC(date: Date): string;