Fixed bug - Loading Indicator now functions correctly

lib/services/flood_station_provider.dart

@@ -1,14 +1,22 @@
 import 'package:flutter/material.dart';
+import 'package:async/async.dart';
 
 import '../model/flood_station.dart';
 import 'api.dart';
 
 class FloodStationProvider extends ChangeNotifier {
   FloodStation? selectedStation;
+  bool filtered = false;
 
   List<FloodStation> _allStations = [];
+  List<FloodStation> _filteredStations = [];
 
   List<FloodStation> get allStations => _allStations;
+  List<FloodStation> get filteredStations => _filteredStations;
+
+  CancelableOperation? _filteredStationsFuture;
+
+  CancelableOperation? get filteredStationsFuture => _filteredStationsFuture;
 
   Future loadAllStationsInBatches({silent = false}) {
     int offset = 0;
@@ -37,4 +45,26 @@ class FloodStationProvider extends ChangeNotifier {
       },
     );
   }
+
+  Future loadFilteredStations(String filter, {silent = false}) {
+    if (_filteredStationsFuture != null) {
+      _filteredStationsFuture!.cancel();
+    }
+    final future = Api.fetchFilteredStations(filter);
+    _filteredStationsFuture = CancelableOperation.fromFuture(future).then(
+      (value) {
+        _filteredStations = value;
+        if (!silent) {
+          notifyListeners();
+        }
+      },
+    );
+    return future;
+  }
+
+  void cancelFilterLoading() {
+    if (_filteredStationsFuture != null) {
+      _filteredStationsFuture!.cancel();
+    }
+  }
 }