initial codex commit

lib/components/calculator/calculator.dart

@@ -97,7 +97,10 @@ class _StationAutocompleteState extends State<StationAutocomplete> {
 }
 
 class RouteCalculator extends StatefulWidget {
-  const RouteCalculator({super.key});
+  const RouteCalculator({super.key, this.onDistanceComputed, this.onApplyRoute});
+
+  final ValueChanged<double>? onDistanceComputed;
+  final ValueChanged<RouteResult>? onApplyRoute;
 
   @override
   State<RouteCalculator> createState() => _RouteCalculatorState();
@@ -143,11 +146,11 @@ class _RouteCalculatorState extends State<RouteCalculator> {
       setState(() {
         _routeResult = RouteResult.fromJson(res);
       });
+      final distance = (_routeResult?.distance ?? 0);
+      widget.onDistanceComputed?.call(distance);
     } else {
       setState(() {
-        _errorMessage =
-            RouteError.fromJson(res["error_obj"][0]).msg ??
-            'Unknown error occurred';
+        _errorMessage = RouteError.fromJson(res["error_obj"][0]).msg;
       });
     }
   }
@@ -248,11 +251,21 @@ class _RouteCalculatorState extends State<RouteCalculator> {
               style: TextStyle(color: Theme.of(context).colorScheme.error),
             ),
           )
-        else if (_routeResult != null)
+        else if (_routeResult != null) ...[
           RouteSummaryWidget(
             distance: _routeResult!.distance,
             onDetailsPressed: () => setState(() => _showDetails = true),
-          )
+          ),
+          if (widget.onApplyRoute != null)
+            Padding(
+              padding: const EdgeInsets.symmetric(horizontal: 16.0),
+              child: ElevatedButton.icon(
+                onPressed: () => widget.onApplyRoute!(_routeResult!),
+                icon: const Icon(Icons.check),
+                label: const Text('Apply to entry'),
+              ),
+            ),
+        ]
         else
           SizedBox.shrink(),
         const SizedBox(height: 10),