xiao_pet_tracker/lib/app/view/app.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_blue_plus_windows/flutter_blue_plus_windows.dart';
import 'package:shadcn_ui/shadcn_ui.dart';
import 'package:xiao_pet_tracker/home/view/home_page.dart';
import 'package:xiao_pet_tracker/l10n/l10n.dart';
import 'package:xiao_pet_tracker/screens/bluetooth_off_screen.dart';

class App extends StatefulWidget {
  const App({super.key});

  @override
  State<App> createState() => _AppState();
}

class _AppState extends State<App> {
  BluetoothAdapterState _adapterState = BluetoothAdapterState.unknown;

  late StreamSubscription<BluetoothAdapterState> _adapterStateStateSubscription;

  @override
  void initState() {
    super.initState();
    _adapterStateStateSubscription =
        FlutterBluePlus.adapterState.listen((state) {
      _adapterState = state;
      if (mounted) {
        setState(() {});
      }
    });
  }

  @override
  void dispose() {
    _adapterStateStateSubscription.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    Widget screen = _adapterState == BluetoothAdapterState.on
        ? const HomePage()
        : BluetoothOffScreen(
            adapterState: _adapterState,
          );

    return ShadApp.material(
      localizationsDelegates: AppLocalizations.localizationsDelegates,
      supportedLocales: AppLocalizations.supportedLocales,
      navigatorObservers: [BluetoothAdapterStateObserver()],
      home: screen,
    );
  }
}

// This observer listens for Bluetooth Off and dismisses the DeviceScreen
class BluetoothAdapterStateObserver extends NavigatorObserver {
  StreamSubscription<BluetoothAdapterState>? _adapterStateSubscription;

  @override
  void didPush(Route route, Route? previousRoute) {
    super.didPush(route, previousRoute);
    if (route.settings.name == '/DeviceScreen') {
      // Start listening to Bluetooth state changes when a new route is pushed
      _adapterStateSubscription ??=
          FlutterBluePlus.adapterState.listen((state) {
        if (state != BluetoothAdapterState.on) {
          // Pop the current route if Bluetooth is off
          navigator?.pop();
        }
      });
    }
  }

  @override
  void didPop(Route route, Route? previousRoute) {
    super.didPop(route, previousRoute);
    // Cancel the subscription when the route is popped
    _adapterStateSubscription?.cancel();
    _adapterStateSubscription = null;
  }
}