import type { GeoPoint } from "./types.ts";
/**
 * WGS84 equatorial radius, metres (NIMA TR8350.2).
 *
 * @example
 * ```ts
 * import { WGS84_A_M } from "@johnmorrisdotca/chikyu-earth";
 *
 * console.log(WGS84_A_M);
 * ```
 */
export declare const WGS84_A_M = 6378137;
/**
 * WGS84 flattening (NIMA TR8350.2).
 *
 * @example
 * ```ts
 * import { WGS84_F } from "@johnmorrisdotca/chikyu-earth";
 *
 * console.log(WGS84_F.toFixed(12));
 * ```
 */
export declare const WGS84_F: number;
/**
 * Mean Earth radius, kilometres, the same sphere the city distances use.
 *
 * @example
 * ```ts
 * import { MEAN_RADIUS_KM } from "@johnmorrisdotca/chikyu-earth";
 *
 * console.log(MEAN_RADIUS_KM);
 * ```
 */
export declare const MEAN_RADIUS_KM = 6371.0088;
/**
 * The speed a flight-time estimate assumes, in kilometres an hour: a jet's cruise, with no wind, climb or holding.
 *
 * @example
 * ```ts
 * import { FLIGHT_SPEED_KM_H } from "@johnmorrisdotca/chikyu-earth";
 *
 * console.log(FLIGHT_SPEED_KM_H);
 * ```
 */
export declare const FLIGHT_SPEED_KM_H = 900;
/**
 * The distance and the bearings between two places.
 *
 * @example
 * ```ts
 * import type { RouteLeg } from "@johnmorrisdotca/chikyu-earth";
 *
 * const none: RouteLeg | null = null;
 * console.log(none);
 * ```
 */
export interface RouteLeg {
    /** Geodesic distance on WGS84, kilometres. The great-circle distance when the geodesic did not converge. */
    kilometres: number;
    /** Great-circle distance on a sphere of {@link MEAN_RADIUS_KM}, kilometres. */
    greatCircleKm: number;
    /** Degrees clockwise from north, 0 to 360, at the start. */
    initialBearing: number;
    /** Degrees clockwise from north, 0 to 360, at the end. */
    finalBearing: number;
    /** Hours at {@link FLIGHT_SPEED_KM_H}. */
    flightHours: number;
    /** The point halfway along the geodesic (or the great circle, when the geodesic did not converge). */
    midpoint: GeoPoint;
    /** False when Vincenty's formula did not converge (nearly antipodal): the distance is then the great circle. */
    exact: boolean;
}
/**
 * The great-circle distance, kilometres, on a sphere of {@link MEAN_RADIUS_KM}. The same angle `trackSteps` uses between two unit vectors.
 *
 * @param from - The start, degrees.
 * @param to - The end, degrees.
 * @returns The distance, or null when a place is not on the Earth.
 *
 * @example
 * ```ts
 * import { greatCircleKm } from "@johnmorrisdotca/chikyu-earth";
 *
 * console.log(greatCircleKm({ lon: 0, lat: 0 }, { lon: 0, lat: 0 }));
 * ```
 */
export declare function greatCircleKm(from: GeoPoint, to: GeoPoint): number | null;
/**
 * Distance, bearings, midpoint and a flight-time estimate between two places. The distance quoted is the WGS84 geodesic.
 * The flight time is that distance at {@link FLIGHT_SPEED_KM_H}, an estimate with no wind.
 *
 * @param from - The start, degrees.
 * @param to - The end, degrees.
 * @returns The leg, or null when a place is not on the Earth.
 *
 * @example
 * ```ts
 * import { routeLeg } from "@johnmorrisdotca/chikyu-earth";
 *
 * const leg = routeLeg({ lon: 0, lat: 0 }, { lon: 1, lat: 0 });
 * console.log(leg?.kilometres.toFixed(3), leg?.initialBearing);
 * ```
 */
export declare function routeLeg(from: GeoPoint, to: GeoPoint): RouteLeg | null;
/**
 * Points along the geodesic from `from` to `to`, including both ends. `count` is how many (2 when they are the same place, 64 when left out).
 * When the geodesic does not converge, the points are the great circle (`trackSteps`).
 *
 * @param from - The start.
 * @param to - The end.
 * @param count - How many points, at least 2.
 * @returns The points, or an empty list when a place is not on the Earth.
 *
 * @example
 * ```ts
 * import { routePoints } from "@johnmorrisdotca/chikyu-earth";
 *
 * console.log(routePoints({ lon: 0, lat: 0 }, { lon: 1, lat: 0 }, 3).length);
 * ```
 */
export declare function routePoints(from: GeoPoint, to: GeoPoint, count?: number): GeoPoint[];
/**
 * The runs of a route after it is split at the date line, so a flat map draws two pieces instead of a line across the world.
 * A run that does not cross is one piece. Uses `splitDateLine`.
 *
 * @param points - Points in order along the route, including the ends.
 * @returns One list of points per piece.
 *
 * @example
 * ```ts
 * import { routeRuns } from "@johnmorrisdotca/chikyu-earth";
 *
 * console.log(routeRuns([{ lon: 179, lat: 0 }, { lon: -179, lat: 0 }]).length);
 * ```
 */
export declare function routeRuns(points: readonly GeoPoint[]): GeoPoint[][];
/**
 * Read the `route` attribute: `lon,lat,lon,lat`. Anything else is no route.
 *
 * @param value - The attribute's text, or null.
 * @returns The two places, or null.
 *
 * @example
 * ```ts
 * import { readRoute } from "@johnmorrisdotca/chikyu-earth";
 *
 * console.log(readRoute("139.69,35.69,-0.13,51.51")?.from.lat);
 * console.log(readRoute("no"));
 * ```
 */
export declare function readRoute(value: string | null | undefined): {
    from: GeoPoint;
    to: GeoPoint;
} | null;
/**
 * The `route` attribute for two places, four decimals.
 *
 * @param route - The two places.
 * @returns `lon,lat,lon,lat`.
 *
 * @example
 * ```ts
 * import { routeText } from "@johnmorrisdotca/chikyu-earth";
 *
 * console.log(routeText({ from: { lon: 1, lat: 2 }, to: { lon: 3, lat: 4 } }));
 * ```
 */
export declare function routeText(route: {
    from: GeoPoint;
    to: GeoPoint;
}): string;