import { MathHelpers } from '@igortrindade/lazyfy'

export const getDistanceAndBearing = (lat1: number, lon1: number, lat2: number, lon2: number) => {
  const R = 6371e3; // metres
  const φ1 = lat1 * Math.PI / 180; // φ, λ in radians
  const φ2 = lat2 * Math.PI / 180;
  const Δφ = (lat2-lat1) * Math.PI / 180;
  const Δλ = (lon2-lon1) * Math.PI / 180;

  const a = Math.sin(Δφ/2) * Math.sin(Δφ/2) +
    Math.cos(φ1) * Math.cos(φ2) *
    Math.sin(Δλ/2) * Math.sin(Δλ/2);
  const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));

  const distance = MathHelpers.round((R * c), 2); // in metres

  let bearing = Math.atan2(Math.sin(Δλ) * Math.cos(φ2), Math.cos(φ1) * Math.sin(φ2) - Math.sin(φ1) * Math.cos(φ2) * Math.cos(Δλ));
  bearing = MathHelpers.round(((bearing * 180 / Math.PI + 360) % 360), 0) // convert to degrees

  return { distance, bearing }

}