package utils

import "math"

func Haversine(lat1, lon1, lat2, lon2 float64) float64 {
	// Radius of the Earth in kilometers
	R := 6371.0

	lat1 = lat1 * math.Pi / 180
	lon1 = lon1 * math.Pi / 180
	lat2 = lat2 * math.Pi / 180
	lon2 = lon2 * math.Pi / 180

	dlat := lat2 - lat1
	dlon := lon2 - lon1

	a := math.Sin(dlat/2)*math.Sin(dlat/2) + math.Cos(lat1)*math.Cos(lat2)*math.Sin(dlon/2)*math.Sin(dlon/2)
	c := 2 * math.Atan2(math.Sqrt(a), math.Sqrt(1-a))

	distance := R * c
	return distance
}