first commit

lib/helper/distance.dart

@@ -0,0 +1,25 @@
+import 'dart:math';
+
+/// Calculate distance between two coordinates in km
+double calculateDistance(double lat1, double lon1, double lat2, double lon2) {
+  const double earthRadius = 6371; // km
+  final dLat = _degreesToRadians(lat2 - lat1);
+  final dLon = _degreesToRadians(lon2 - lon1);
+
+  final a = sin(dLat / 2) * sin(dLat / 2) +
+      cos(_degreesToRadians(lat1)) *
+          cos(_degreesToRadians(lat2)) *
+          sin(dLon / 2) *
+          sin(dLon / 2);
+
+  final c = 2 * atan2(sqrt(a), sqrt(1 - a));
+  final distance = earthRadius * c;
+
+  return distance;
+}
+
+double _degreesToRadians(double degrees) {
+  return degrees * pi / 180;
+}
+
+