Upstream sync

shared/user_data.go

@@ -4,7 +4,28 @@
 
 package shared
 
+import "math"
+
 const (
 	RoleAdmin   string = "admin"
 	RoleProUser string = "pro-user"
 )
+
+func DistanceKm(lat1 float64, lng1 float64, lat2 float64, lng2 float64) float64 {
+	radlat1 := float64(math.Pi * lat1 / 180)
+	radlat2 := float64(math.Pi * lat2 / 180)
+
+	theta := float64(lng1 - lng2)
+	radtheta := float64(math.Pi * theta / 180)
+
+	dist := math.Sin(radlat1)*math.Sin(radlat2) + math.Cos(radlat1)*math.Cos(radlat2)*math.Cos(radtheta)
+	if dist > 1 {
+		dist = 1
+	}
+
+	dist = math.Acos(dist)
+	dist = dist * 180 / math.Pi
+	dist = dist * 60 * 1.1515
+
+	return dist * 1.609344
+}