add data service and homepage data retrieval

lib/services/apiService.dart

@@ -1,6 +1,5 @@
 import 'dart:convert';
 import 'package:http/http.dart' as http;
-import 'package:mileograph_flutter/services/authservice.dart';
 
 typedef TokenProvider = String? Function();
 

lib/services/authservice.dart

@@ -1,4 +1,3 @@
-import 'package:provider/provider.dart';
 import 'package:flutter/foundation.dart';
 import 'package:mileograph_flutter/objects/objects.dart';
 import 'package:mileograph_flutter/services/apiService.dart';
@@ -65,4 +64,9 @@ class AuthService extends ChangeNotifier {
       email: userResponse['email'],
     );
   }
+
+  void logout() {
+    _user = null;
+    notifyListeners();
+  }
 }

lib/services/dataService.dart

@@ -0,0 +1,51 @@
+import 'package:flutter/foundation.dart';
+import 'package:mileograph_flutter/objects/objects.dart';
+import 'package:mileograph_flutter/services/apiService.dart'; // assumes you've moved HomepageStats + submodels to a separate file
+
+class DataService extends ChangeNotifier {
+  final ApiService api;
+
+  DataService({required this.api});
+
+  HomepageStats? _homepageStats;
+  HomepageStats? get homepageStats => _homepageStats;
+
+  bool _isHomepageLoading = false;
+  bool get isHomepageLoading => _isHomepageLoading;
+
+  Future<void> fetchHomepageStats() async {
+    _isHomepageLoading = true;
+    notifyListeners();
+
+    try {
+      final json = await api.get('/stats/homepage');
+      _homepageStats = HomepageStats.fromJson(json);
+    } catch (e) {
+      debugPrint('Failed to fetch homepage stats: $e');
+      _homepageStats = null;
+    } finally {
+      _isHomepageLoading = false;
+      notifyListeners();
+    }
+  }
+
+  void clear() {
+    _homepageStats = null;
+    notifyListeners();
+  }
+
+  double getMileageForCurrentYear() {
+    final currentYear = DateTime.now().year;
+    return getMileageForYear(currentYear) ?? 0;
+  }
+
+  double? getMileageForYear(int year) {
+    return _homepageStats?.yearlyMileage
+            .firstWhere(
+              (entry) => entry.year == year,
+              orElse: () => YearlyMileage(year: null, mileage: 0),
+            )
+            .mileage ??
+        0;
+  }
+}