Fix: BLE connection only allowed one update without app restart

Author: samruddhi-Rahegaonkar

lib/bademagic_module/bluetooth/connect_state.dart

@@ -12,7 +12,13 @@ class ConnectState extends RetryBleState {
   @override
   Future<BleState?> processState() async {
     bool connected = false;
-
+    try {
+      await scanResult.device.disconnect();
+      logger.d("Pre-emptive disconnect for clean state");
+      await Future.delayed(const Duration(seconds: 1));
+    } catch (_) {
+      // Ignore disconnect errors
+    }
     try {
       await scanResult.device.connect(autoConnect: false);
       BluetoothConnectionState connectionState =

lib/bademagic_module/bluetooth/scan_state.dart

@@ -2,11 +2,11 @@ import 'dart:async';
 import 'package:badgemagic/bademagic_module/bluetooth/connect_state.dart';
 import 'package:badgemagic/bademagic_module/bluetooth/datagenerator.dart';
 import 'package:flutter_blue_plus/flutter_blue_plus.dart';
-
 import 'base_ble_state.dart';
 
 class ScanState extends NormalBleState {
   final DataTransferManager manager;
+
   ScanState({required this.manager});
 
   @override
@@ -17,59 +17,72 @@ class ScanState extends NormalBleState {
     Completer<BleState?> nextStateCompleter = Completer();
     bool isCompleted = false;
 
-    ScanResult? foundDevice;
-
     try {
       subscription = FlutterBluePlus.scanResults.listen(
         (results) async {
-          if (!isCompleted) {
-            if (results.isNotEmpty) {
-              foundDevice = results.firstWhere(
+          if (!isCompleted && results.isNotEmpty) {
+            try {
+              final foundDevice = results.firstWhere(
                 (result) => result.advertisementData.serviceUuids
                     .contains(Guid("0000fee0-0000-1000-8000-00805f9b34fb")),
+                orElse: () => throw Exception("Matching device not found."),
               );
-              if (foundDevice != null) {
-                toast.showToast('Device found. Connecting...');
-                isCompleted = true;
-                nextStateCompleter.complete(ConnectState(
-                  scanResult: foundDevice!,
-                  manager: manager,
-                ));
-              }
+              toast.showToast('Device found. Connecting...');
+              isCompleted = true;
+              await FlutterBluePlus.stopScan();
+              nextStateCompleter.complete(ConnectState(
+                scanResult: foundDevice,
+                manager: manager,
+              ));
+
+              toast.showToast('Device found. Connecting...');
+              isCompleted = true;
+              FlutterBluePlus.stopScan();
+
+              nextStateCompleter.complete(ConnectState(
+                scanResult: foundDevice,
+                manager: manager,
+              ));
+            } catch (e) {
+              //ignore and keep scanning
             }
           }
         },
-        onError: (e) async {
+        onError: (e) {
           if (!isCompleted) {
             isCompleted = true;
+            FlutterBluePlus.stopScan();
             logger.e("Scan error: $e");
             toast.showErrorToast('Scan error occurred.');
-            nextStateCompleter.completeError(e);
+            nextStateCompleter
+                .completeError(Exception("Error during scanning: $e"));
           }
         },
       );
 
       await FlutterBluePlus.startScan(
         withServices: [Guid("0000fee0-0000-1000-8000-00805f9b34fb")],
-        removeIfGone: Duration(seconds: 5),
+        removeIfGone: const Duration(seconds: 5),
         continuousUpdates: true,
-        timeout: const Duration(seconds: 15), // Reduced scan timeout
+        timeout: const Duration(seconds: 15),
       );
 
       await Future.delayed(const Duration(seconds: 1));
 
-      // If no device is found after the scan timeout, complete with an error.
       if (!isCompleted) {
+        isCompleted = true;
+        FlutterBluePlus.stopScan();
         toast.showToast('Device not found.');
         nextStateCompleter.completeError(Exception('Device not found.'));
       }
 
       return await nextStateCompleter.future;
     } catch (e) {
       logger.e("Exception during scanning: $e");
-      throw Exception("please check the device is turned on and retry.");
+      throw Exception("Please check if the device is turned on and retry.");
     } finally {
       await subscription?.cancel();
+      await FlutterBluePlus.stopScan();
     }
   }
 }

lib/bademagic_module/bluetooth/write_state.dart

@@ -27,16 +27,19 @@ class WriteState extends NormalBleState {
               for (int attempt = 1; attempt <= 3; attempt++) {
                 try {
                   await characteristic.write(chunk, withoutResponse: false);
+                  logger.d("Chunk written successfully: $chunk");
                   success = true;
                   break;
                 } catch (e) {
-                  logger.e("Write failed, retrying ($attempt/3): $e");
+                  logger.e("Write failed (attempt $attempt/3): $e");
                 }
               }
               if (!success) {
                 throw Exception("Failed to transfer data. Please try again.");
               }
+              await Future.delayed(Duration(milliseconds: 50));
             }
+
             logger.d("Characteristic written successfully");
             return CompletedState(
                 isSuccess: true, message: "Data transferred successfully");