class SphMercProjection {
  constructor() {
    this.EARTH = 40075016.68;
    this.HALF_EARTH = 20037508.34;
  }

  project(lon, lat) {
    return [this.lonToSphMerc(lon), this.latToSphMerc(lat)];
  }

  unproject(projected) {
    return [this.sphMercToLon(projected[0]), this.sphMercToLat(projected[1])];
  }

  lonToSphMerc(lon) {
    return (lon / 180) * this.HALF_EARTH;
  }

  latToSphMerc(lat) {
    var y = Math.log(Math.tan(((90 + lat) * Math.PI) / 360)) / (Math.PI / 180);
    return (y * this.HALF_EARTH) / 180.0;
  }

  sphMercToLon(x) {
    return (x / this.HALF_EARTH) * 180.0;
  }

  sphMercToLat(y) {
    var lat = (y / this.HALF_EARTH) * 180.0;
    lat =
      (180 / Math.PI) *
      (2 * Math.atan(Math.exp((lat * Math.PI) / 180)) - Math.PI / 2);
    return lat;
  }

  getID() {
    return "epsg:3857";
  }
}

export { SphMercProjection };