import { FeatureCollection, Point, Feature, Polygon, MultiPolygon } from 'geojson';
import { Units } from '@turf/helpers';

/**
 * Takes a set of {@link Point|points} and returns a concave hull Polygon or MultiPolygon.
 * Internally, this uses [turf-tin](https://github.com/Turfjs/turf-tin) to generate geometries.
 *
 * @function
 * @param {FeatureCollection<Point>} points input points
 * @param {Object} [options={}] Optional parameters
 * @param {number} [options.maxEdge=Infinity] the length (in 'units') of an edge necessary for part of the
 * hull to become concave.
 * @param {string} [options.units='kilometers'] can be degrees, radians, miles, or kilometers
 * @returns {Feature<(Polygon|MultiPolygon)>|null} a concave hull (null value is returned if unable to compute hull)
 * @example
 * var points = turf.featureCollection([
 *   turf.point([-63.601226, 44.642643]),
 *   turf.point([-63.591442, 44.651436]),
 *   turf.point([-63.580799, 44.648749]),
 *   turf.point([-63.573589, 44.641788]),
 *   turf.point([-63.587665, 44.64533]),
 *   turf.point([-63.595218, 44.64765])
 * ]);
 * var options = {units: 'miles', maxEdge: 1};
 *
 * var hull = turf.concave(points, options);
 *
 * //addToMap
 * var addToMap = [points, hull]
 */
declare function concave(points: FeatureCollection<Point>, options?: {
    maxEdge?: number;
    units?: Units;
}): Feature<Polygon | MultiPolygon> | null;

export { concave, concave as default };