export interface Point {
  x: number;
  y: number;
}

export interface geoPoint {
  lon: number;
  lat: number;
}

// cf https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames#ECMAScript_(JavaScript/ActionScript,_etc.)
export const lon2tile = (lon: number, zoom: number) => {
  return ((Number(lon) + 180) / 360) * Math.pow(2, zoom);
};
export const lat2tile = (lat: number, zoom: number) => {
  return (
    ((1 -
      Math.log(
        Math.tan((Number(lat) * Math.PI) / 180) +
          1 / Math.cos((Number(lat) * Math.PI) / 180)
      ) /
        Math.PI) /
      2) *
    Math.pow(2, zoom)
  );
};

export function tile2long(x: number, z: number) {
  return (x / Math.pow(2, z)) * 360 - 180;
}

export function tile2lat(y: number, z: number) {
  var n = Math.PI - (2 * Math.PI * y) / Math.pow(2, z);
  return (180 / Math.PI) * Math.atan(0.5 * (Math.exp(n) - Math.exp(-n)));
}