Added feature to show the battery level of the current obs device

lib/events.dart

@@ -36,6 +36,9 @@
 //
 // buttonData: task -> main
 // {"time": int}
+//
+// batteryLevel: task -> main
+// {"level": int}
 
 enum EventName {
   requestLocationState,
@@ -50,6 +53,7 @@ enum EventName {
   disconnected,
   distanceData,
   buttonData,
+  batteryLevel,
 }
 
 enum LocationState {
@@ -109,6 +113,8 @@ abstract class EventData {
         return DistanceDataEvent.fromJson(json);
       case EventName.buttonData:
         return ButtonDataEvent.fromJson(json);
+      case EventName.batteryLevel:
+        return BatteryLevelEvent.fromJson(json);
       default:
         throw ArgumentError('Switch fallthrough:Invalid event name');
     }
@@ -331,3 +337,26 @@ class ButtonDataEvent extends EventData {
     }
   }
 }
+
+class BatteryLevelEvent extends EventData {
+  BatteryLevelEvent({required this.level})
+      : super(event: EventName.batteryLevel);
+
+  final int level;
+
+  @override
+  Map<String, dynamic> toJson() => {
+        'event': event.toString().split('.').last,
+        'level': level,
+      };
+
+  factory BatteryLevelEvent.fromJson(Map<String, dynamic> json) {
+    if (json.containsKey('level')) {
+      return BatteryLevelEvent(
+        level: json['level'],
+      );
+    } else {
+      throw ArgumentError('Invalid JSON data for BatteryLevelEvent');
+    }
+  }
+}

lib/foreground_task/bluetooth.dart

@@ -5,6 +5,9 @@ import 'package:flutter_blue_plus/flutter_blue_plus.dart';
 import 'package:sentry_flutter/sentry_flutter.dart';
 
 // The services that should be exposed by the OpenBikeSensor
+Guid batteryServiceID = Guid("0000180F-0000-1000-8000-00805F9B34FB");
+Guid batteryCharacteristic = Guid("00002A19-0000-1000-8000-00805F9B34FB");
+
 Guid deviceServiceID = Guid("0000180A-0000-1000-8000-00805F9B34FB");
 Guid firmwareCharacteristic = Guid("00002a26-0000-1000-8000-00805f9b34fb");
 Guid nameCharacteristic = Guid("00002a29-0000-1000-8000-00805f9b34fb");
@@ -15,7 +18,7 @@ Guid buttonCharacteristic = Guid("1FE7FAF9-CE63-4236-0004-000000000003");
 Guid offsetCharacteristic = Guid("1FE7FAF9-CE63-4236-0004-000000000004");
 Guid trackidCharacteristic = Guid("1FE7FAF9-CE63-4236-0004-000000000005");
 
-enum BluetoothEvent { distance, button, offset, trackId, firmware }
+enum BluetoothEvent { distance, button, offset, trackId, firmware, battery }
 
 typedef BluetoothCallbackFunction = Function(BluetoothEvent, CallbackResults);
 typedef DiscoveredDeviceCallbackFunction = Function(List<BluetoothDevice>);
@@ -36,6 +39,7 @@ class CallbackResults {
   int distance1 = 0;
   int distance2 = 0;
   int clock = 0;
+  int batteryLevel = 0;
 }
 
 class Bluetooth {
@@ -48,6 +52,7 @@ class Bluetooth {
   // Subscription to the distance and button characteristics
   StreamSubscription<List<int>>? _distanceSubscription;
   StreamSubscription<List<int>>? _buttonSubscription;
+  StreamSubscription<List<int>>? _batterySubscription;
 
   StreamSubscription<OnDiscoveredServicesEvent>? _servicesSubscription;
 
@@ -67,6 +72,7 @@ class Bluetooth {
     _servicesSubscription?.cancel();
     _distanceSubscription?.cancel();
     _buttonSubscription?.cancel();
+    _batterySubscription?.cancel();
   }
 
   static Bluetooth? _instance;
@@ -276,6 +282,14 @@ class Bluetooth {
     _notifyCharacteristicCallbacks(BluetoothEvent.trackId, data);
   }
 
+  void _handleBatteryLevelCharacteristic(List<int> valueList) {
+    if (valueList.isEmpty) {
+      throw Exception("Invalid battery level characteristic");
+    }
+    final CallbackResults data = CallbackResults()..batteryLevel = valueList[0];
+    _notifyCharacteristicCallbacks(BluetoothEvent.battery, data);
+  }
+
   // Discover all services exposed by the device
   Future<void> subscribeToCharacteristics(
       BluetoothCallbackFunction callback) async {
@@ -296,6 +310,16 @@ class Bluetooth {
       firmware.lastValueStream.listen(handleFirmwareCharacteristic);
       await firmware.read();
 
+      // BatteryService
+      // https://www.bluetooth.com/wp-content/uploads/Files/Specification/HTML/BAS_v1.1/out/en/index-en.html#UUID-fb902c2f-32bc-833c-8eb6-245fc3a52b81
+      final batteryService = services
+          .firstWhere((element) => element.uuid == batteryServiceID)
+          .characteristics;
+      final battery = batteryService
+          .firstWhere((element) => element.uuid == batteryCharacteristic);
+      battery.setNotifyValue(true);
+      battery.lastValueStream.listen(_handleBatteryLevelCharacteristic);
+
       // Handle the obsService
       final obsCharacteristics = services
           .firstWhere((element) => element.uuid == obsServiceID)

lib/foreground_task/task_handler.dart

@@ -314,6 +314,11 @@ class ForegroundTaskHandler extends TaskHandler {
         break;
       case BluetoothEvent.trackId:
         break; // unused
+      case BluetoothEvent.battery:
+        _sendMessageToUI(BatteryLevelEvent(
+          level: data.batteryLevel,
+        ));
+
       default:
         throw Exception("Unknown event $event");
     }

lib/main.dart

@@ -3,6 +3,7 @@ import 'dart:io';
 
 import 'package:app/generated/i18n/app_localizations.dart';
 import 'package:app/manager/background_manger.dart';
+import 'package:app/providers/battery_provider.dart';
 import 'package:app/providers/bluetooth_provider.dart';
 import 'package:app/providers/button_provider.dart';
 import 'package:app/providers/location_provider.dart';
@@ -29,6 +30,7 @@ Future<void> main() async {
       ChangeNotifierProvider(create: (context) => ButtonProvider()),
       ChangeNotifierProvider(create: (context) => TripProvider()),
       ChangeNotifierProvider(create: (context) => LocationProvider()),
+      ChangeNotifierProvider(create: (context) => BatteryProvider()),
     ],
     child: const MyApp(),
   );

lib/manager/background_manger.dart

 import 'dart:convert';
 import 'package:app/foreground_task/bluetooth.dart';
 import 'package:app/foreground_task/task_handler.dart';
+import 'package:app/providers/battery_provider.dart';
 import 'package:app/providers/bluetooth_provider.dart';
 import 'package:app/providers/button_provider.dart';
 import 'package:app/providers/distance_provider.dart';
@@ -129,6 +130,8 @@ class BackgroundManager {
           Provider.of<ButtonProvider>(_context!, listen: false);
       final locationProvider =
           Provider.of<LocationProvider>(_context!, listen: false);
+      final batteryProvider =
+          Provider.of<BatteryProvider>(_context!, listen: false);
 
       final event = EventData.fromJson(jsonData);
 
@@ -185,6 +188,10 @@ class BackgroundManager {
         case EventName.buttonData:
           buttonProvider.setButton();
           break;
+        case EventName.batteryLevel:
+          final batteryLevel = (event as BatteryLevelEvent).level;
+          batteryProvider.setBatteryLevel(batteryLevel);
+          break;
         default:
           throw Exception("Unknown event ${event.event}");
       }

lib/providers/battery_provider.dart

+import 'package:flutter/material.dart';
+
+class BatteryProvider extends ChangeNotifier {
+  int batteryLevel = -1; // No information about the battery available
+
+  BatteryProvider();
+
+  void setBatteryLevel(int level) {
+    batteryLevel = level;
+    notifyListeners();
+  }
+}

lib/widgets/bluetooth_status.dart

 import 'package:app/foreground_task/bluetooth.dart';
+import 'package:app/providers/battery_provider.dart';
 import 'package:app/providers/bluetooth_provider.dart';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
@@ -19,7 +20,7 @@ class _BluetoothStatusState extends State<BluetoothStatus> {
   }
 
   // return a text widget based on the location status
-  Widget locationText(BleState state, ConnectionResult? device) {
+  Widget bluetoothStatusText(BleState state, ConnectionResult? device) {
     final localizations = AppLocalizations.of(context)!;
 
     switch (state) {
@@ -43,9 +44,36 @@ class _BluetoothStatusState extends State<BluetoothStatus> {
     }
   }
 
+  Widget batteryState(int batteryLevel) {
+    Icon batteryIcon = Icon(Icons.battery_unknown);
+    if (batteryLevel < 0) {
+      batteryIcon = Icon(Icons.battery_unknown);
+    } else if (batteryLevel < 10) {
+      batteryIcon = Icon(Icons.battery_0_bar);
+    } else if (batteryLevel < 20) {
+      batteryIcon = Icon(Icons.battery_2_bar);
+    } else if (batteryLevel < 40) {
+      batteryIcon = Icon(Icons.battery_3_bar);
+    } else if (batteryLevel < 60) {
+      batteryIcon = Icon(Icons.battery_4_bar);
+    } else if (batteryLevel < 80) {
+      batteryIcon = Icon(Icons.battery_5_bar);
+    } else if (batteryLevel < 100) {
+      batteryIcon = Icon(Icons.battery_6_bar);
+    } else if (batteryLevel == 100) {
+      batteryIcon = Icon(Icons.battery_full);
+    }
+
+    return Row(children: [
+      Icon(Icons.battery_5_bar),
+      Text(batteryLevel >= 0 ? '$batteryLevel%' : '')
+    ]);
+  }
+
   @override
   Widget build(BuildContext context) {
     final bluetoothProvider = context.watch<BluetoothProvider>();
+    final batteryProvider = context.watch<BatteryProvider>();
 
     return Card(
       child: ListTile(
@@ -56,8 +84,11 @@ class _BluetoothStatusState extends State<BluetoothStatus> {
         subtitle: Column(
           crossAxisAlignment: CrossAxisAlignment.start,
           children: [
-            locationText(bluetoothProvider.connectionState,
+            bluetoothStatusText(bluetoothProvider.connectionState,
                 bluetoothProvider.connectedDevice),
+            bluetoothProvider.connectionState == BleState.connected
+                ? batteryState(batteryProvider.batteryLevel)
+                : SizedBox.shrink()
           ],
         ),
       ),