export type SegmentType = "year" | "month" | "day" | "hour" | "minute" | "dayPeriod";
/** Keys match {@link SegmentType}. */
export interface SegmentLabels {
    year: string;
    month: string;
    day: string;
    hour: string;
    minute: string;
    dayPeriod: string;
}
/** What an empty segment prompts: the letters of the digits it takes, in every language, as a date
 *  reads `dd/MM/yyyy` in every language. */
export declare const SEGMENT_PLACEHOLDERS: SegmentLabels;
export type LayoutSegment = {
    kind: "field";
    type: SegmentType;
} | {
    kind: "literal";
    value: string;
};
export interface DateLayout {
    /** Locale display order. */
    segments: LayoutSegment[];
    hour12: boolean;
    /** Only meaningful when hour12. */
    amText: string;
    pmText: string;
}
/** `hour` is canonical 0–23 regardless of display. */
export interface SegmentBuffer {
    year: number | null;
    month: number | null;
    day: number | null;
    hour: number | null;
    minute: number | null;
}
export declare function emptyBuffer(): SegmentBuffer;
/** Exported so the segments and `time_options` agree on 12/24-hour. */
export declare const TIME_FORMAT_OPTIONS: Intl.DateTimeFormatOptions;
export declare function getDateLayout(locale: string, hasTime: boolean): DateLayout;
export declare function getTimeLayout(locale: string): DateLayout;
/** Literals dropped. */
export declare function fieldOrder(layout: DateLayout): SegmentType[];
export declare function to12h(hour24: number): {
    h12: number;
    pm: boolean;
};
export declare function from12h(h12: number, pm: boolean): number;
export interface DigitResult {
    text: string;
    /** Display domain: 1–12 for `hour` in 12h mode. */
    value: number;
    /** Full: focus advances. */
    complete: boolean;
}
export declare function typeDigit(type: SegmentType, currentText: string, digit: string, hour12: boolean): DigitResult;
/**
 * A lone "1" might be "12", so a typed separator is the explicit advance; a leading one is a no-op,
 * as in native date inputs.
 */
export declare function separatorAdvances(key: string, segmentHasContent: boolean): boolean;
/** Wrapping within range. */
export declare function incrementSegment(type: SegmentType, current: number | null, delta: number, hour12: boolean): number;
export declare function setHourField(buffer: SegmentBuffer, typed: number, hour12: boolean): number;
/** Preserving the displayed 12-hour value. */
export declare function withDayPeriod(buffer: SegmentBuffer, pm: boolean): number;
/** Null when unset. */
export declare function displayValue(type: SegmentType, buffer: SegmentBuffer, layout: DateLayout): string | null;
export declare function valueToSegments(iso: string, hasTime: boolean): SegmentBuffer;
export declare function isBufferEmpty(buffer: SegmentBuffer, hasTime: boolean): boolean;
/** Null when incomplete or invalid. */
export declare function segmentsToValue(buffer: SegmentBuffer, hasTime: boolean): string | null;
export interface SegmentsConfig {
    layout: DateLayout;
    toBuffer: (value: string) => SegmentBuffer;
    toValue: (buffer: SegmentBuffer) => string | null;
    isEmpty: (buffer: SegmentBuffer) => boolean;
    /** Null when unparseable. */
    parse: (text: string) => string | null;
}
export declare function dateSegmentsConfig(locale: string, hasTime: boolean): SegmentsConfig;
/** Unparseable or out of range reads as empty. */
export declare function timeToSegments(time: string): SegmentBuffer;
/** Null while either half is missing. */
export declare function segmentsToTime(buffer: SegmentBuffer): string | null;
export declare function timeSegmentsConfig(locale: string): SegmentsConfig;