import { Feature, Polygon } from 'geojson';
import { Coord } from '@turf/helpers';

/**
 * Takes a triangular plane as a polygon and a point within that triangle, and
 * returns the z-value at that point.
 *
 * The Polygon should have properties `a`, `b`, and `c`
 * that define the values at its three corners. Alternatively, the z-values
 * of each triangle point can be provided by their respective 3rd coordinate
 * if their values are not provided as properties.
 *
 * @function
 * @param {Coord} point the Point for which a z-value will be calculated
 * @param {Feature<Polygon>} triangle a Polygon feature with three vertices
 * @returns {number} the z-value for `interpolatedPoint`
 * @example
 * const point = turf.point([-75.3221, 39.529]);
 * // "a", "b", and "c" values represent the values of the coordinates in order.
 * const triangle = turf.polygon([[
 *   [-75.1221, 39.57],
 *   [-75.58, 39.18],
 *   [-75.97, 39.86],
 *   [-75.1221, 39.57]
 * ]], {
 *   "a": 11,
 *   "b": 122,
 *   "c": 44
 * });
 *
 * const zValue = turf.planepoint(point, triangle);
 * point.properties.zValue = zValue;
 *
 * //addToMap
 * const addToMap = [triangle, point];
 */
declare function planepoint(point: Coord, triangle: Feature<Polygon> | Polygon): number;

export { planepoint as default, planepoint };