/**
 * Astronomy utilities — moon phase, moonrise/moonset, and extended twilight.
 *
 * All computation is local via `astronomy-engine` (±1 arcminute accuracy,
 * zero transitive dependencies) — pure, deterministic, no I/O, no caching.
 * Times are returned as Luxon DateTimes in the zone of the input date, so
 * callers pass the forecast's IANA timezone once and formatting stays simple.
 */
import { DateTime } from 'luxon';
import type { UnitPreferences } from '../config/units.js';
/**
 * Astronomy facts for one calendar day at one location.
 *
 * All ten time fields are nullable: a null means the event does not occur
 * during that calendar day. For the moon this happens routinely (the moon
 * rises ~50 minutes later each day, so about once a month a day has no
 * moonrise or no moonset); for twilight it happens in polar conditions.
 */
export interface DayAstronomy {
    /** One of the 8 standard phase names (New Moon, Waxing Crescent, ...). */
    phaseName: string;
    /** Illuminated fraction of the moon's disc, 0-100. */
    illuminationPct: number;
    moonrise: DateTime | null;
    moonset: DateTime | null;
    civilDawn: DateTime | null;
    civilDusk: DateTime | null;
    nauticalDawn: DateTime | null;
    nauticalDusk: DateTime | null;
    astroDawn: DateTime | null;
    astroDusk: DateTime | null;
    /**
     * Sun altitude (degrees) at local solar noon (approximated as clock noon).
     * Used by the formatter to distinguish "polar day" (sun never descends to
     * a twilight threshold) from "polar night" (sun never ascends to it) when
     * a twilight event is missing.
     */
    sunNoonAltitude: number;
}
/** The next full and new moon instants after a given time. */
export interface NextMoonQuarters {
    nextFull: DateTime;
    nextNew: DateTime;
}
/**
 * Bucket a moon phase angle (0-360°, 0 = new, 180 = full) into one of the 8
 * standard phase names. Buckets are centered on the principal phases, so the
 * date USNO labels "New Moon" reports "New Moon" here (e.g. 350° and 10° are
 * both New Moon; boundaries fall at 22.5°, 67.5°, ..., 337.5°).
 */
export declare function moonPhaseName(phaseAngle: number): string;
/**
 * Compute moon phase, moonrise/moonset, and civil/nautical/astronomical
 * dawn+dusk for the calendar day containing `date` (in `date`'s zone) at the
 * given coordinates.
 *
 * Phase and illumination are evaluated at local noon — a representative
 * instant for "the" phase of a calendar day.
 */
export declare function computeDayAstronomy(latitude: number, longitude: number, date: DateTime): DayAstronomy;
/**
 * Find the next full moon and next new moon after `from`.
 * Iterates the lunar quarter sequence (new=0, first=1, full=2, third=3);
 * both are always found within one synodic month (4-5 iterations).
 */
export declare function nextMoonQuarters(from: DateTime): NextMoonQuarters;
/**
 * Format the per-day astronomy block — the two lines added to each daily
 * forecast entry when `include_astronomy` is set:
 *
 *   **Moon:** Waxing Gibbous (78% illuminated) · Rise 3:42 PM · Set 1:15 AM
 *   **Twilight:** Civil 5:29 AM / 9:02 PM · Nautical 4:47 AM / 9:44 PM · Astronomical 3:58 AM / 10:33 PM
 *
 * Every field always renders: missing moon rise/set shows "none" (a normal
 * monthly occurrence at any latitude), missing twilight shows the polar
 * wording. Ends with a trailing newline.
 */
export declare function formatAstronomyBlock(astro: DayAstronomy, prefs: UnitPreferences): string;
/**
 * Format the once-per-response next-quarters line:
 *
 *   **Next full moon:** Aug 27 · **Next new moon:** Sep 11
 *
 * Dates are rendered in the forecast's IANA timezone. Ends with a trailing
 * newline.
 */
export declare function formatNextQuarters(quarters: NextMoonQuarters, timezone: string): string;
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