import proj4 from "proj4";
import type { Point } from "../karte/types";

const ETRS25832 =
  "+proj=utm +zone=32 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs +type=crs";

proj4.defs("EPSG:25832", ETRS25832);

export function toEtrs(lon: number, lat: number): Point {
  const projected = proj4("EPSG:4326", "EPSG:25832", [lon, lat]);
  return { easting: projected[0], northing: projected[1] };
}

export function watchStandort(
  onStandort: (standort: Point | "denied") => void,
): () => void {
  if (!navigator.geolocation) {
    onStandort("denied");
    return () => {};
  }

  const id = navigator.geolocation.watchPosition(
    (position) => {
      onStandort(toEtrs(position.coords.longitude, position.coords.latitude));
    },
    (error) => {
      if (error.code === error.PERMISSION_DENIED) onStandort("denied");
    },
    { enableHighAccuracy: true },
  );

  return () => navigator.geolocation.clearWatch(id);
}