import 'dart:async';
import 'dart:io';

import 'package:camera/camera.dart';
import 'package:firebase_storage/firebase_storage.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:path/path.dart' as Path;

import 'package:video_player/video_player.dart';

class VideoRecorderExample extends StatefulWidget {
  @override
  _VideoRecorderExampleState createState() {
    return _VideoRecorderExampleState();
  }
}

class _VideoRecorderExampleState extends State<VideoRecorderExample> {
  CameraController controller;
  String videoPath;

  List<CameraDescription> cameras;
  int selectedCameraIdx;

  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();

  @override
  void initState() {
    super.initState();

    // Get the listonNewCameraSelected of available cameras.
    // Then set the first camera as selected.
    availableCameras().then((availableCameras) {
      cameras = availableCameras;

      if (cameras.length > 0) {
        setState(() {
          selectedCameraIdx = 0;
        });

        _onCameraSwitched(cameras[selectedCameraIdx]).then((void v) {});
      }
    }).catchError((err) {
      print('Error: $err.code\nError Message: $err.message');
    });
  }

  @override
  void dispose() {
    controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(
        title: const Text('Camera example'),
      ),
      body: Column(
        children: <Widget>[
          Expanded(
            child: Container(
              child: Padding(
                padding: const EdgeInsets.all(1.0),
                child: Center(
                  child: _cameraPreviewWidget(),
                ),
              ),
              decoration: BoxDecoration(
                color: Colors.black,
                border: Border.all(
                  color: controller != null && controller.value.isRecordingVideo
                      ? Colors.redAccent
                      : Colors.grey,
                  width: 3.0,
                ),
              ),
            ),
          ),
          Padding(
            padding: const EdgeInsets.all(5.0),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.start,
              children: <Widget>[
                _cameraTogglesRowWidget(),
                _captureControlRowWidget(),
                Expanded(
                  child: SizedBox(),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  IconData _getCameraLensIcon(CameraLensDirection direction) {
    switch (direction) {
      case CameraLensDirection.back:
        return Icons.camera_rear;
      case CameraLensDirection.front:
        return Icons.camera_front;
      case CameraLensDirection.external:
        return Icons.camera;
      default:
        return Icons.device_unknown;
    }
  }

  // Display 'Loading' text when the camera is still loading.
  Widget _cameraPreviewWidget() {
    if (controller == null || !controller.value.isInitialized) {
      return const Text(
        'Loading',
        style: TextStyle(
          color: Colors.white,
          fontSize: 20.0,
          fontWeight: FontWeight.w900,
        ),
      );
    }

    return AspectRatio(
      aspectRatio: controller.value.aspectRatio,
      child: CameraPreview(controller),
    );
  }

  /// Display a row of toggle to select the camera (or a message if no camera is available).
  Widget _cameraTogglesRowWidget() {
    if (cameras == null) {
      return Row();
    }

    CameraDescription selectedCamera = cameras[selectedCameraIdx];
    CameraLensDirection lensDirection = selectedCamera.lensDirection;

    return Expanded(
      child: Align(
        alignment: Alignment.centerLeft,
        child: FlatButton.icon(
            onPressed: _onSwitchCamera,
            icon: Icon(_getCameraLensIcon(lensDirection)),
            label: Text(
                "${lensDirection.toString().substring(lensDirection.toString().indexOf('.') + 1)}")),
      ),
    );
  }

  /// Display the control bar with buttons to record videos.
  Widget _captureControlRowWidget() {
    return Expanded(
      child: Align(
        alignment: Alignment.center,
        child: Row(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          mainAxisSize: MainAxisSize.max,
          children: <Widget>[
            IconButton(
              icon: const Icon(Icons.videocam),
              color: Colors.blue,
              onPressed: controller != null &&
                      controller.value.isInitialized &&
                      !controller.value.isRecordingVideo
                  ? _onRecordButtonPressed
                  : null,
            ),
            IconButton(
              icon: const Icon(Icons.stop),
              color: Colors.red,
              onPressed: controller != null &&
                      controller.value.isInitialized &&
                      controller.value.isRecordingVideo
                  ? _onStopButtonPressed
                  : null,
            )
          ],
        ),
      ),
    );
  }

  String timestamp() => DateTime.now().millisecondsSinceEpoch.toString();

  Future<void> _onCameraSwitched(CameraDescription cameraDescription) async {
    if (controller != null) {
      await controller.dispose();
    }

    controller = CameraController(cameraDescription, ResolutionPreset.high);

    // If the controller is updated then update the UI.
    controller.addListener(() {
      if (mounted) {
        setState(() {});
      }

      if (controller.value.hasError) {
        print(controller.value.errorDescription);
      }
    });

    try {
      await controller.initialize();
    } on CameraException catch (e) {
      _showCameraException(e);
    }

    if (mounted) {
      setState(() {});
    }
  }

  void _onSwitchCamera() {
    selectedCameraIdx =
        selectedCameraIdx < cameras.length - 1 ? selectedCameraIdx + 1 : 0;
    CameraDescription selectedCamera = cameras[selectedCameraIdx];

    _onCameraSwitched(selectedCamera);

    setState(() {
      selectedCameraIdx = selectedCameraIdx;
    });
  }

  void _onRecordButtonPressed() {
    _startVideoRecording().then((String filePath) {
      if (filePath != null) {
        print('recoding start');
      }
    });
  }

  void _onStopButtonPressed() {
    _stopVideoRecording().then((_) async {
      if (mounted) setState(() {});
      print('video path $videoPath');
      File _video = File(videoPath);
      StorageReference storageReference = FirebaseStorage.instance.ref().child(
          'videos/${Path.basename(DateTime.now().toIso8601String())}}'); //use basename(_image.path) if dont want duplicate
      StorageUploadTask uploadTask = storageReference.putFile(_video);
      await uploadTask.onComplete;
      print('File Uploaded');
      storageReference.getDownloadURL().then((fileURL) {
        print('the downloading url is $fileURL');
      });
    });
  }

  Future<String> _startVideoRecording() async {
    if (!controller.value.isInitialized) {
      print('please wait');
      return null;
    }

    // Do nothing if a recording is on progress
    if (controller.value.isRecordingVideo) {
      return null;
    }

    final Directory appDirectory = await getExternalStorageDirectory();
    final String videoDirectory = '${appDirectory.path}/Videos';
    await Directory(videoDirectory).create(recursive: true);
    final String currentTime = DateTime.now().millisecondsSinceEpoch.toString();
    final String filePath = '$videoDirectory/$currentTime.mp4';

    try {
      await controller.startVideoRecording(filePath);
      videoPath = filePath;
    } on CameraException catch (e) {
      _showCameraException(e);
      return null;
    }

    return filePath;
  }

  Future<void> _stopVideoRecording() async {
    if (!controller.value.isRecordingVideo) {
      return null;
    }

    try {
      await controller.stopVideoRecording();
    } on CameraException catch (e) {
      _showCameraException(e);
      return null;
    }
  }

  void _showCameraException(CameraException e) {
    String errorText = 'Error: ${e.code}\nError Message: ${e.description}';
    print(errorText);
  }
}

Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, v1.9.1+hotfix.4, on Microsoft Windows [Version 10.0.18362.356], locale en-IN)
 
[√] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
[√] Android Studio (version 3.2)
[!] IntelliJ IDEA Ultimate Edition (version 2018.3)
    X Flutter plugin not installed; this adds Flutter specific functionality.
    X Dart plugin not installed; this adds Dart specific functionality.
[√] Connected device (1 available)

! Doctor found issues in 1 category.

dependencies:
  flutter:
    sdk: flutter
  provider: ^3.1.0
  firebase_storage: ^3.0.6
  image_picker: ^0.6.1+4
  camera: ^0.5.5+1
  video_player: ^0.10.2+3
  path_provider: ^1.3.0