import 'package:flutter/material.dart';
import 'package:logger/logger.dart';
import 'package:camera/camera.dart';

var logger = Logger(
  printer: PrettyPrinter(),
);

late List<CameraDescription> _cameras;

Future<void> main() async {
  try {
    WidgetsFlutterBinding.ensureInitialized();
    _cameras = await availableCameras();
  } on CameraException catch (e) {
    logger.e('Error in fetching the cameras:', e);
  }

  _cameras = await availableCameras();
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Tensordex',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.lightBlue,
      ),
      home: const TensordexHome(title: 'Tensordex'),
    );
  }
}

class TensordexHome extends StatefulWidget {
  const TensordexHome({Key? key, required this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  State<TensordexHome> createState() => _TensordexHomeState();
}

class _TensordexHomeState extends State<TensordexHome> with WidgetsBindingObserver {
  int _counter = 0;
  late CameraController controller;
  bool _isCameraInitialized = false;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
      logger.d("Counter Incremented!");
      logger.w("Counter Incremented!");
      logger.e("Counter Incremented!");
    });
  }

  void onNewCameraSelected(CameraDescription cameraDescription) async {
    final previousCameraController = controller;
    // Instantiating the camera controller
    final CameraController cameraController = CameraController(
      cameraDescription,
      ResolutionPreset.high,
      imageFormatGroup: ImageFormatGroup.jpeg,
    );

    // Dispose the previous controller
    await previousCameraController.dispose();

    // Replace with the new controller
    if (mounted) {
      setState(() {
        controller = cameraController;
      });
    }

    // Update UI if controller updated
    cameraController.addListener(() {
      if (mounted) setState(() {});
    });

    // Initialize controller
    try {
      await cameraController.initialize();
    } on CameraException catch (e) {
      logger.e('Error initializing camera:', e);
    }

    // Update the Boolean
    if (mounted) {
      setState(() {
        _isCameraInitialized = controller.value.isInitialized;
      });
    }
  }


  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    final CameraController cameraController = controller;

    switch (state) {
      case AppLifecycleState.resumed:
      // --
        logger.i('Resumed');
        break;
      case AppLifecycleState.inactive:
      // --
        logger.i('Inactive');
        break;
      case AppLifecycleState.paused:
      // --
        logger.i('Paused');
        break;
      case AppLifecycleState.detached:
      // --
        logger.i('Detached');
        break;
    }
    // App state changed before we got the chance to initialize.
    if (!cameraController.value.isInitialized) {
      return;
    }

    if (state == AppLifecycleState.inactive) {
      // Free up memory when camera not active
      cameraController.dispose();
    } else if (state == AppLifecycleState.resumed) {
      // Reinitialize the camera with same properties
      onNewCameraSelected(cameraController.description);
    }
  }
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);


    controller = CameraController(_cameras[0], ResolutionPreset.max);
    controller.initialize().then((_) {
      if (!mounted) {
        return;
      }

      setState(() {onNewCameraSelected(_cameras[0]);});
    }).catchError((Object e) {
      if (e is CameraException) {
        switch (e.code) {
          case 'CameraAccessDenied':
            logger.w('User denied camera access.');
            controller.initialize().then((_) {
              if (!mounted) {
                return;
              }
              setState(() {});
            }).catchError((Object e) {
              if (e is CameraException) {
                switch (e.code) {
                  case 'CameraAccessDenied':
                    logger.i('User denied camera access.');
                    break;
                  default:
                    logger.i('Handle other errors.');
                    break;
                }
              }
            });
            break;
          default:
            logger.i('Handle other errors.');
            break;
        }
      }
    });
  }

  @override
  void dispose() {
    controller.dispose();
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.

    return Scaffold(
        appBar: AppBar(
          // Here we take the value from the MyHomePage object that was created by
          // the App.build method, and use it to set our appbar title.
          title: Text(widget.title),
        ),
        body: Center(
          // Center is a layout widget. It takes a single child and positions it
          // in the middle of the parent.
          child: Column(
            // Column is also a layout widget. It takes a list of children and
            // arranges them vertically. By default, it sizes itself to fit its
            // children horizontally, and tries to be as tall as its parent.
            //
            // Invoke "debug painting" (press "p" in the console, choose the
            // "Toggle Debug Paint" action from the Flutter Inspector in Android
            // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
            // to see the wireframe for each widget.
            //
            // Column has various properties to control how it sizes itself and
            // how it positions its children. Here we use mainAxisAlignment to
            // center the children vertically; the main axis here is the vertical
            // axis because Columns are vertical (the cross axis would be
            // horizontal).
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              const Text(
                'You have pushed the button this many times:',
              ),
              Text(
                '$_counter',
                style: Theme.of(context).textTheme.headline4,
              ),
              controller.value.isInitialized
                  ? CameraPreview(controller)
                  : const Text("Please enable the camera!"),
            ],
          ),
        ),
        floatingActionButton: GestureDetector(
          onLongPress: () {
            _incrementCounter();
          },
          child: FloatingActionButton(
            onPressed: _incrementCounter,
            tooltip: 'Increment',
            child: const Icon(Icons.photo_camera),
          ), // This trailing comma makes auto-formatting nicer for build methods.
        ));
  }
}