export type SelectionMode = 'none' | 'default' | 'one' | 'zeroOrOne' | 'oneExtended' | 'many' | 'zeroOrMany' | 'oneOrMany' | 'week' | 'range';
export type SelectionModifiers = {
    ctrl?: boolean;
    shift?: boolean;
};
export type SelectionState = {
    /** Selected days (deduped, sorted ascending), always local-midnight. */
    dates: Date[];
    /** Anchor for shift-extend (oneExtended). */
    anchor: Date | null;
    /** Pending range start (range mode, between first and second click). */
    rangeStart: Date | null;
};
export declare const emptySelection: () => SelectionState;
/** True when `day` is in `dates` (by calendar day). */
export declare function isSelected(dates: ReadonlyArray<Date>, day: Date): boolean;
/** Inclusive ordered list of day-midnight dates from a..b (either order). */
export declare function rangeDays(a: Date, b: Date): Date[];
/**
 * Apply a click on `clicked` to `state` under `mode`. `firstDayOfWeek` only
 * matters for `week` mode. Returns a fresh state (never mutates the input).
 */
export declare function selectDate(state: SelectionState, clicked: Date, mode: SelectionMode, modifiers?: SelectionModifiers, firstDayOfWeek?: number): SelectionState;
/** Whether a mode ever holds more than one date (drives multi-select UI hints). */
export declare function isMultiSelectMode(mode: SelectionMode): boolean;