import type { Temporal } from "@js-temporal/polyfill";
import type { CalendarSystem } from "../types/index.js";
import { type CalendarDateStringParts } from "./calendarDateString.js";
/**
 * Split a Temporal.PlainDate into GMT's calendar-annotated string halves (`{ date, annotation }`)
 * in a known target CalendarSystem — the shared primitive behind both `formatDateInCalendar`
 * (`plain/`) and `internal/calendarZonedString.ts`'s `formatZonedInCalendar` (`zoned/`).
 *
 * The two namespaces need the halves joined differently — `plain/` concatenates them directly,
 * while GMT's zoned grammar splices `T<time><offset>` between them and appends `[<timeZone>]`
 * (see `regex/calendar-zoned-date-time.ts` for why `[u-ca=...]` precedes `[timeZone]`). Sharing
 * the split rather than string-slicing `formatDateInCalendar`'s output on `"["` keeps the era,
 * Ethiopic-family and zero-padding logic in exactly one place per calendar family.
 *
 * The calendar must always be known up front and passed in explicitly, never re-derived from
 * `date.calendarId` alone: the Ethiopic family ("ethiopic" / "ethiopic-amete-alem" / "coptic")
 * is backed by Temporal's single, ambiguous "ethioaa" id, which cannot tell the three variants
 * apart from the PlainDate object alone (see `ethiopicFamilyCalendar.ts`).
 *
 * @param date Temporal.PlainDate to split, already calendared as `calendar` expects
 *   (`"ethioaa"` for any Ethiopic-family member, its own Temporal calendar id otherwise)
 * @param calendar the CalendarSystem `date` is known to represent
 * @returns `{ date, annotation }` — `annotation` is `""` for the "gregorian"/iso8601 case
 */
export declare function calendarDateStringParts(date: Temporal.PlainDate, calendar: CalendarSystem): CalendarDateStringParts;
/**
 * Format a Temporal.PlainDate as a GMT calendar-annotated (or bare ISO) string in a known
 * target CalendarSystem — companion to `calendarSystemOfDateValue`.
 *
 * The calendar must always be known up front and passed in explicitly, never re-derived from
 * `date.calendarId` alone: the Ethiopic family ("ethiopic" / "ethiopic-amete-alem" / "coptic")
 * is backed by Temporal's single, ambiguous "ethioaa" id, which cannot tell the three variants
 * apart from the PlainDate object alone (see `ethiopicFamilyCalendar.ts`).
 *
 * Within a known target calendar, though, the *fields* (year, era, month, day) are always
 * re-derived from the actual resulting `date`, never copied from an input string's tag —
 * `calendarDateParts`/`ethiopicFamilyDateParts` both already do this per-call, which is
 * required because calendar-unit arithmetic can cross a leap-month or era boundary (Hebrew
 * Adar I -> Adar, Japanese Heisei -> Reiwa): a copied tag would describe a date that no longer
 * exists (E5 decision of record D7).
 *
 * @param date Temporal.PlainDate to format, already calendared as `calendar` expects
 *   (`"ethioaa"` for any Ethiopic-family member, its own Temporal calendar id otherwise)
 * @param calendar the CalendarSystem `date` is known to represent
 * @returns GMT's calendar-annotated (or bare ISO, for "gregorian") PlainDate string
 */
export declare function formatDateInCalendar(date: Temporal.PlainDate, calendar: CalendarSystem): string;