export default class PolylineUtility {
  private static encodeNum(num: number): string {
    let pnum: number = num << 1;
    if (num < 0) pnum = ~pnum;

    if (pnum == 0) {
      return String.fromCharCode(63);
    } else {
      let result: string = '';
      while (pnum > 0x1f) {
        const c: number = ((pnum & 0x1f) | 0x20) + 63;
        result += String.fromCharCode(c);
        pnum = pnum >>> 5;
      }
      result += String.fromCharCode(63 + pnum);
      return result;
    }
  }

  public static decodeNums(str: string): { lon: number; lat: number; alt: number; radius: number } {
    const result: number[] = [];

    let current: number = 0;
    let pos: number = 0;
    for (const c of str) {
      const code: number = c.charCodeAt(0);
      const num: number = code - 63;
      current |= (num & 0x1f) << pos;
      pos += 5;
      if (num <= 0x1f) {
        let tmpres: number = current >>> 1;
        if ((current & 0x1) === 1) {
          tmpres = ~tmpres;
        }
        result.push(tmpres);
        current = 0;
        pos = 0;
      }
    }
    
    return { lon: result[0] / 1e5, lat: result[1] / 1e5, alt: result[2], radius: result[3] }

  }

  public static encodeCompetitionTurnpoint(lon: number, lat: number, alt: number, radius: number): string {
    const lonStr: string = PolylineUtility.encodeNum(Math.round(lon * 1e5));
    const latStr: string = PolylineUtility.encodeNum(Math.round(lat * 1e5));
    const altStr: string = PolylineUtility.encodeNum(alt);
    const radiusStr: string = PolylineUtility.encodeNum(radius);
    return lonStr + latStr + altStr + radiusStr;

    // For decoding just use decodeNums and assign numbers in correct order.
    // Do not forget divide coordinations by 1e5f
  }
}