Add fallback backends with respect to load + Backend rework

lib/common/layout/dialog.dart

@@ -31,11 +31,11 @@ void showInvalidShortcutSheet(context) {
       ),
     ),
     pageBuilder: (BuildContext dialogContext, Animation<double> animation, Animation<double> secondaryAnimation) {
-      final backend = getIt<Settings>().backend;
+      final city = getIt<Settings>().city;
       return DialogLayout(
         title: 'Ungültige Strecke',
         text:
-            "Die ausgewählte Strecke ist ungültig, da sie Wegpunkte enthält, die außerhalb des Stadtgebietes von ${backend.region} liegen.\nPrioBike wird aktuell nur innerhalb von ${backend.region} unterstützt.",
+            "Die ausgewählte Strecke ist ungültig, da sie Wegpunkte enthält, die außerhalb des Stadtgebietes von ${city.nameDE} liegen.\nPrioBike wird aktuell nur innerhalb von ${city.nameDE} unterstützt.",
         actions: [
           BigButtonPrimary(
             label: 'Schließen',

lib/common/map/image_cache.dart

@@ -9,6 +9,7 @@ import 'package:priobike/http.dart';
 import 'package:priobike/logging/logger.dart';
 import 'package:priobike/logging/toast.dart';
 import 'package:priobike/main.dart';
+import 'package:priobike/settings/models/backend.dart';
 import 'package:priobike/settings/services/auth.dart';
 import 'package:priobike/settings/services/settings.dart';
 import 'package:shared_preferences/shared_preferences.dart';
@@ -58,7 +59,7 @@ class MapboxTileImageCache {
     try {
       // See: https://docs.mapbox.com/api/maps/static-images/
       final settings = getIt<Settings>();
-      final auth = await Auth.load(settings.backend);
+      final auth = await Auth.load(settings.city.selectedBackend(true));
       final accessTokenHeader = "access_token=${auth.mapboxAccessToken}";
       String styleId = "";
       // remove prefix "mapbox://styles/" from the styles

lib/common/map/layers/poi_layers.dart

@@ -26,7 +26,7 @@ class ParkingStationsLayer {
   /// Install the source of the layer on the map controller.
   _installSource(mapbox.MapboxMap mapController) async {
     final settings = getIt<Settings>();
-    final baseUrl = settings.backend.path;
+    final baseUrl = settings.city.selectedBackend(true).path;
     await mapController.style.addSource(
       mapbox.GeoJsonSource(id: sourceId, data: "https://$baseUrl/map-data/bicycle_parking_v2.geojson"),
     );
@@ -129,7 +129,7 @@ class RentalStationsLayer {
   /// Install the source of the layer on the map controller.
   _installSource(mapbox.MapboxMap mapController) async {
     final settings = getIt<Settings>();
-    final baseUrl = settings.backend.path;
+    final baseUrl = settings.city.selectedBackend(true).path;
     await mapController.style.addSource(
       mapbox.GeoJsonSource(id: sourceId, data: "https://$baseUrl/map-data/bicycle_rental_v2.geojson"),
     );
@@ -308,7 +308,7 @@ class BikeShopLayer {
   /// Install the source of the layer on the map controller.
   _installSource(mapbox.MapboxMap mapController) async {
     final settings = getIt<Settings>();
-    final baseUrl = settings.backend.path;
+    final baseUrl = settings.city.selectedBackend(true).path;
     await mapController.style.addSource(
       mapbox.GeoJsonSource(id: sourceId, data: "https://$baseUrl/map-data/bicycle_shop_v2.geojson"),
     );
@@ -482,7 +482,7 @@ class BikeAirStationLayer {
   /// Install the source of the layer on the map controller.
   _installSource(mapbox.MapboxMap mapController) async {
     final settings = getIt<Settings>();
-    final baseUrl = settings.backend.path;
+    final baseUrl = settings.city.selectedBackend(true).path;
     await mapController.style.addSource(
       mapbox.GeoJsonSource(id: sourceId, data: "https://$baseUrl/map-data/bike_air_station_v2.geojson"),
     );

lib/common/map/layers/prio_layers.dart

@@ -26,7 +26,7 @@ class GreenWaveLayer {
   /// Install the source of the layer on the map controller.
   _installSource(mapbox.MapboxMap mapController) async {
     final settings = getIt<Settings>();
-    final baseUrl = settings.backend.path;
+    final baseUrl = settings.city.selectedBackend(true).path;
     await mapController.style.addSource(
       mapbox.GeoJsonSource(id: sourceId, data: "https://$baseUrl/map-data/static_green_waves_v2.geojson"),
     );
@@ -83,7 +83,7 @@ class VeloRoutesLayer {
   /// Install the source of the layer on the map controller.
   _installSource(mapbox.MapboxMap mapController) async {
     final settings = getIt<Settings>();
-    final baseUrl = settings.backend.path;
+    final baseUrl = settings.city.selectedBackend(true).path;
     await mapController.style.addSource(
       mapbox.GeoJsonSource(id: sourceId, data: "https://$baseUrl/map-data/velo_routes_v2.geojson", tolerance: 1),
     );
@@ -135,7 +135,7 @@ class IntersectionsLayer {
   _installSource(mapbox.MapboxMap mapController) async {
     try {
       final settings = getIt<Settings>();
-      final baseUrl = settings.backend.path;
+      final baseUrl = settings.city.selectedBackend(true).path;
 
       final url = "https://$baseUrl/sg-selector-nginx/intersections.json.gz";
       final endpoint = Uri.parse(url);

lib/common/map/view.dart

@@ -138,8 +138,8 @@ class AppMapState extends State<AppMap> {
       cameraOptions: mapbox.CameraOptions(
         center: mapbox.Point(
           coordinates: mapbox.Position(
-            settings.backend.center.longitude,
-            settings.backend.center.latitude,
+            settings.city.center.longitude,
+            settings.city.center.latitude,
           ),
         ),
         zoom: 12,

lib/feedback/services/feedback.dart

@@ -49,7 +49,7 @@ class Feedback with ChangeNotifier {
 
     // Send all of the answered questions to the backend.
     final settings = getIt<Settings>();
-    final baseUrl = settings.backend.path;
+    final baseUrl = settings.city.selectedBackend(true).path;
     final endpoint = Uri.parse('https://$baseUrl/tracking-service/answers/post/');
     for (final entry in pending.values.toList().asMap().entries) {
       final request = PostAnswerRequest(

lib/home/models/backend_status.dart

@@ -0,0 +1,24 @@
+class BackendStatus {
+  /// If another backend should be used.
+  final bool recommendOtherBackend;
+
+  /// If the backend has a load warning.
+  final bool warning;
+
+  /// The timestamp of the current load status data.
+  final DateTime timestamp;
+
+  BackendStatus({required this.recommendOtherBackend, required this.warning, required this.timestamp});
+
+  factory BackendStatus.fromJson(Map<String, dynamic> json) => BackendStatus(
+        recommendOtherBackend: json['recommendOtherBackend'],
+        warning: json['warning'],
+        timestamp: DateTime.fromMillisecondsSinceEpoch(json['timestamp'] * 1000),
+      );
+
+  Map<String, dynamic> toJson() => {
+        'recommendOtherBackend': recommendOtherBackend,
+        'warning': warning,
+        'timestamp': timestamp.millisecondsSinceEpoch,
+      };
+}

lib/home/services/link_shortener.dart

@@ -9,7 +9,7 @@ import 'package:priobike/settings/services/settings.dart';
 class LinkShortener {
   /// Shorten long link.
   static Future<String?> createShortLink(String longLink) async {
-    final backend = getIt<Settings>().backend;
+    final backend = getIt<Settings>().city.selectedBackend(false);
     String backendPath = backend.path;
     final linkShortenerUrl = 'https://$backendPath/link/rest/v3/short-urls';
     final linkShortenerEndpoint = Uri.parse(linkShortenerUrl);
@@ -40,7 +40,7 @@ class LinkShortener {
     // Shortcuts from production and release should be working with each others backend.
     // Therefore, try fetch from the current backend and (if failed) from the other backend.
     // Only staging is not compatible with the other backends.
-    final backend = getIt<Settings>().backend;
+    final backend = getIt<Settings>().city.selectedBackend(false);
     final String? result = await _fetch(backend, shortLink);
     if (result != null) return result;
     if (backend == Backend.staging) return null;

lib/home/services/load.dart

@@ -1,91 +1,75 @@
 import 'dart:convert';
 
 import 'package:flutter/material.dart';
+import 'package:priobike/home/models/backend_status.dart';
 import 'package:priobike/http.dart';
 import 'package:priobike/logging/logger.dart';
+import 'package:priobike/logging/toast.dart';
 import 'package:priobike/main.dart';
-import 'package:priobike/settings/models/backend.dart';
-import 'package:priobike/settings/services/settings.dart';
+import 'package:priobike/settings/services/features.dart';
 
 class LoadStatus with ChangeNotifier {
   /// If the service is currently loading the status history.
   bool isLoading = false;
 
-  /// The warning that should be displayed.
-  String? text;
-
   /// If there exists a warning.
   bool hasWarning = false;
 
+  /// If the fallback backend should be used.
+  bool useFallback = false;
+
   /// Logger for the status history.
   final log = Logger("Load");
 
   LoadStatus();
 
-  /// Fetches the status data from the priobike-load-service.
-  Future<void> fetch() async {
-    if (isLoading) return;
-    isLoading = true;
-
+  /// Fetches the status data and returns if the given backend is usable.
+  Future<void> checkLoad(String baseUrl) async {
     try {
-      final settings = getIt<Settings>();
-      final baseUrl = settings.backend.path;
-
-      final url = "https://$baseUrl/load-service/static/load_response.json";
+      final url = "https://$baseUrl/load-service/load.json";
       final endpoint = Uri.parse(url);
 
       final response = await Http.get(endpoint).timeout(const Duration(seconds: 4));
+
       if (response.statusCode != 200) {
-        isLoading = false;
-        notifyListeners();
         final err = "Error while fetching load status from $endpoint: ${response.statusCode}";
         throw Exception(err);
       }
 
       final json = jsonDecode(response.body);
+      final backendStatus = BackendStatus.fromJson(json);
 
-      if (json["warning"]) {
+      // Load status is updated every minute.
+      // If the timestamp of the status is older than 5 minutes, we assume the backend is not usable.
+      if (DateTime.now().difference(backendStatus.timestamp).inMinutes > 5) {
         hasWarning = true;
-        text = json["response_text"];
+        useFallback = true;
+        log.w("Load status is older than 5 minutes");
       } else {
-        hasWarning = false;
-        text = null;
+        hasWarning = backendStatus.warning;
+        useFallback = backendStatus.recommendOtherBackend;
       }
-
-      isLoading = false;
-      notifyListeners();
     } catch (e, stacktrace) {
-      isLoading = false;
-      notifyListeners();
       final hint = "Error while fetching load status: $e $stacktrace";
       log.e(hint);
     }
-  }
-
-  /// Sends an app start notification to the load service in the backend.
-  Future<void> sendAppStartNotification() async {
-    try {
-      final settings = getIt<Settings>();
-      final baseUrl = settings.backend.path;
 
-      final url = "https://$baseUrl/load-service/app/start";
-      final endpoint = Uri.parse(url);
-
-      final response = await Http.post(endpoint).timeout(const Duration(seconds: 4));
-      if (response.statusCode != 200) {
-        final err = "Error while sending app start to load service $endpoint: ${response.statusCode}";
-        throw Exception(err);
+    if (getIt<Feature>().canEnableInternalFeatures) {
+      // Don't switch the backend if the internal version is used. We want to keep the possibility
+      // to manually set the backend.
+      if (useFallback) {
+        ToastMessage.showError(
+            "Fallback müsste benutzt werden. Aufgrund der internen Version wird das Fallback jedoch nicht benutzt.");
       }
-    } catch (e, stacktrace) {
-      final hint = "Error while sending app start to load service: $e $stacktrace";
-      log.e(hint);
+      useFallback = false;
     }
+
+    notifyListeners();
   }
 
   /// Reset the status.
   Future<void> reset() async {
     hasWarning = false;
-    text = null;
     isLoading = false;
     notifyListeners();
   }

lib/home/services/poi.dart

@@ -146,7 +146,7 @@ class POI with ChangeNotifier {
   /// A method which is used to fetch the POI data from the backend.
   Future<dynamic> _fetchData(String relativeUrl) async {
     final settings = getIt<Settings>();
-    final baseUrl = settings.backend.path;
+    final baseUrl = settings.city.selectedBackend(true).path;
     final dataUrl = "https://$baseUrl$relativeUrl";
     final dataEndpoint = Uri.parse(dataUrl);
 

lib/home/services/shortcuts.dart

@@ -122,9 +122,9 @@ class Shortcuts with ChangeNotifier {
     if (shortcuts == null) return;
     final storage = await SharedPreferences.getInstance();
 
-    final backend = getIt<Settings>().backend;
+    final city = getIt<Settings>().city;
     final jsonStr = jsonEncode(shortcuts!.map((e) => e.toJson()).toList());
-    storage.setString("priobike.home.shortcuts.${backend.regionName}", jsonStr);
+    storage.setString("priobike.home.shortcuts.${city.nameDE}", jsonStr);
 
     // Activates the tutorial if more then 3 (+2 default shortcuts) shortcuts were stored.
     if (shortcuts!.length >= 5) {
@@ -137,11 +137,11 @@ class Shortcuts with ChangeNotifier {
     if (shortcuts != null) return;
     final storage = await SharedPreferences.getInstance();
 
-    final backend = getIt<Settings>().backend;
-    final jsonStr = storage.getString("priobike.home.shortcuts.${backend.regionName}");
+    final city = getIt<Settings>().city;
+    final jsonStr = storage.getString("priobike.home.shortcuts.${city.nameDE}");
 
     if (jsonStr == null) {
-      shortcuts = backend.defaultShortcuts;
+      shortcuts = city.defaultShortcuts;
       await storeShortcuts();
     } else {
       // Init shortcuts.

lib/home/views/load_status.dart

@@ -30,8 +30,8 @@ class LoadStatusViewState extends State<LoadStatusView> {
         context: context,
         builder: (BuildContext context) {
           return DialogLayout(
-            title: "Mehr Nutzende als normalerweise",
-            text: loadStatus.text ?? "",
+            title: "Starke Auslastung",
+            text: "Aktuell sind unsere Server außergewöhnlich stark ausgelastet.",
             actions: [
               BigButtonTertiary(
                 label: "Schließen",
@@ -58,7 +58,7 @@ class LoadStatusViewState extends State<LoadStatusView> {
           children: [
             Flexible(
               child: Content(
-                text: "Mehr Nutzende als normalerweise",
+                text: "Starke Auslastung",
                 context: context,
               ),
             ),

lib/home/views/main.dart

@@ -155,15 +155,13 @@ class HomeViewState extends State<HomeView> with WidgetsBindingObserver, RouteAw
   void didChangeAppLifecycleState(AppLifecycleState state) {
     if (state == AppLifecycleState.resumed) {
       predictionStatusSummary.fetch();
-      loadStatus.fetch();
       news.getArticles();
     }
   }
 
   @override
   void didPopNext() {
     predictionStatusSummary.fetch();
-    loadStatus.fetch();
     news.getArticles();
   }
 
@@ -272,7 +270,6 @@ class HomeViewState extends State<HomeView> with WidgetsBindingObserver, RouteAw
           onRefresh: () async {
             HapticFeedback.lightImpact();
             await predictionStatusSummary.fetch();
-            await loadStatus.fetch();
             await news.getArticles();
             await getIt<Weather>().fetch();
             // Wait for one more second, otherwise the user will get impatient.

lib/home/views/nav.dart

@@ -52,18 +52,18 @@ class NavBarView extends StatelessWidget {
                     context: context,
                   ),
                   Content(
-                    text: settings.backend == Backend.staging ? " DD" : " HH",
+                    text: settings.city == City.dresden ? " DD" : " HH",
                     color: Colors.white,
                     context: context,
                   ),
-                  Flexible(
-                    fit: FlexFit.tight,
-                    child: Small(
-                      text: settings.backend == Backend.production ? "  beta" : "",
-                      color: Colors.white,
-                      context: context,
-                    ),
-                  ),
+                  settings.city.selectedBackend(true) == Backend.production
+                      ? Content(
+                          text: ".",
+                          color: Colors.white,
+                          context: context,
+                        )
+                      : Container(),
+                  Expanded(child: Container()),
                   BoldContent(text: "Moin!", color: Colors.white, context: context),
                 ],
               ),