namespace Graph.Utils;

public static class NodeUtils
{
    public const int EarthRadius = 6371000;
    
    /*
     * Close enough
     */
    public static double DistanceBetween(float lat1, float lon1, float lat2, float lon2)
    {
        double radiansLat1 = DegreesToRadians(lat1);
        double radiansLat2 = DegreesToRadians(lat2);
        double deltaRadiansLon = DegreesToRadians(lon2 - lon1);
        
        double distance = Math.Acos(Math.Sin(radiansLat1) * Math.Sin(radiansLat2) + Math.Cos(radiansLat1) * Math.Cos(radiansLat2) * Math.Cos(deltaRadiansLon)) * EarthRadius;

        return distance;
    }

    public static double DistanceBetween(Node n1, Node n2) => DistanceBetween(n1.Lat, n1.Lon, n2.Lat, n2.Lon);
    public static double DistanceBetween(Node n1, float lat2, float lon2) => DistanceBetween(n1.Lat, n1.Lon, lat2, lon2);
    public static double DistanceBetween(float lat1, float lon1, Node n2) => DistanceBetween(n2, lat1, lon1);
    
    /*
     * From https://www.movable-type.co.uk/scripts/latlong.html
     */
    public static double DistanceBetweenHaversine(float lat1, float lon1, float lat2, float lon2)
    {
        double radiansLat1 = DegreesToRadians(lat1);
        double radiansLat2 = DegreesToRadians(lat2);
        double deltaRadiansLat = DegreesToRadians(lat2 - lat1);
        double deltaRadiansLon = DegreesToRadians(lon2 - lon1);
        double a = Math.Sin(deltaRadiansLat / 2) * Math.Sin(deltaRadiansLat / 2) + Math.Cos(radiansLat1) * Math.Cos(radiansLat2) * Math.Sin(deltaRadiansLon / 2) * Math.Sin(deltaRadiansLon / 2);
        double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
        double d = EarthRadius * c;
        return d;
    }
    
    public static double DegreesToRadians(float deg)
    {
        return deg * Math.PI /180;
    }

    public static double RadiansToDegrees(float rad)
    {
        return rad * 180 / Math.PI;
    }
}