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

import 'package:flutter/material.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:photo_gallery/photo_gallery.dart';
import 'package:transparent_image/transparent_image.dart';
import 'package:video_player/video_player.dart';

void main() {
  runApp(MyApp());
}

/// The main widget of example app
class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  List<Album>? _albums;
  bool _loading = false;

  @override
  void initState() {
    super.initState();
    _loading = true;
    initAsync();
  }

  Future<void> initAsync() async {
    if (await _promptPermissionSetting()) {
      List<Album> albums = await PhotoGallery.listAlbums();
      setState(() {
        _albums = albums;
        _loading = false;
      });
    }
    setState(() {
      _loading = false;
    });
  }

  Future<bool> _promptPermissionSetting() async {
    if (Platform.isIOS) {
      if (await Permission.photos.request().isGranted || await Permission.storage.request().isGranted) {
        return true;
      }
    }
    if (Platform.isAndroid) {
      if (await Permission.storage.request().isGranted ||
          await Permission.photos.request().isGranted &&
              await Permission.videos.request().isGranted) {
        return true;
      }
    }
    return false;
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Photo gallery example'),
        ),
        body: _loading
            ? Center(
                child: CircularProgressIndicator(),
              )
            : LayoutBuilder(
                builder: (context, constraints) {
                  double gridWidth = (constraints.maxWidth - 20) / 3;
                  double gridHeight = gridWidth + 33;
                  double ratio = gridWidth / gridHeight;
                  return Container(
                    padding: EdgeInsets.all(5),
                    child: GridView.count(
                      childAspectRatio: ratio,
                      crossAxisCount: 3,
                      mainAxisSpacing: 5.0,
                      crossAxisSpacing: 5.0,
                      children: <Widget>[
                        ...?_albums?.map(
                          (album) => GestureDetector(
                            onTap: () => Navigator.of(context).push(
                              MaterialPageRoute(builder: (context) => AlbumPage(album)),
                            ),
                            child: Column(
                              children: <Widget>[
                                ClipRRect(
                                  borderRadius: BorderRadius.circular(5.0),
                                  child: Container(
                                    color: Colors.grey[300],
                                    height: gridWidth,
                                    width: gridWidth,
                                    child: FadeInImage(
                                      fit: BoxFit.cover,
                                      placeholder: MemoryImage(kTransparentImage),
                                      image: AlbumThumbnailProvider(
                                        album: album,
                                        highQuality: true,
                                      ),
                                    ),
                                  ),
                                ),
                                Container(
                                  alignment: Alignment.topLeft,
                                  padding: EdgeInsets.only(left: 2.0),
                                  child: Text(
                                    album.name ?? "Unnamed Album",
                                    maxLines: 1,
                                    textAlign: TextAlign.start,
                                    style: TextStyle(
                                      height: 1.2,
                                      fontSize: 16,
                                    ),
                                  ),
                                ),
                                Container(
                                  alignment: Alignment.topLeft,
                                  padding: EdgeInsets.only(left: 2.0),
                                  child: Text(
                                    album.count.toString(),
                                    textAlign: TextAlign.start,
                                    style: TextStyle(
                                      height: 1.2,
                                      fontSize: 12,
                                    ),
                                  ),
                                ),
                              ],
                            ),
                          ),
                        ),
                      ],
                    ),
                  );
                },
              ),
      ),
    );
  }
}

/// The album page widget
class AlbumPage extends StatefulWidget {
  /// Album object to show in the page
  final Album album;

  /// The constructor of AlbumPage
  AlbumPage(Album album) : album = album;

  @override
  State<StatefulWidget> createState() => _AlbumPageState();
}

class _AlbumPageState extends State<AlbumPage> {
  List<Medium>? _media;

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

  void initAsync() async {
    MediaPage mediaPage = await widget.album.listMedia();
    setState(() {
      _media = mediaPage.items;
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          leading: IconButton(
            icon: Icon(Icons.arrow_back_ios),
            onPressed: () => Navigator.of(context).pop(),
          ),
          title: Text(widget.album.name ?? "Unnamed Album"),
        ),
        body: GridView.count(
          crossAxisCount: 3,
          mainAxisSpacing: 1.0,
          crossAxisSpacing: 1.0,
          children: <Widget>[
            ...?_media?.map(
              (medium) => GestureDetector(
                onTap: () => Navigator.of(context).push(
                  MaterialPageRoute(builder: (context) => ViewerPage(medium)),
                ),
                child: Container(
                  color: Colors.grey[300],
                  child: FadeInImage(
                    fit: BoxFit.cover,
                    placeholder: MemoryImage(kTransparentImage),
                    image: ThumbnailProvider(
                      mediumId: medium.id,
                      mediumType: medium.mediumType,
                      highQuality: true,
                    ),
                  ),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

/// The viewer page widget
class ViewerPage extends StatelessWidget {
  /// The medium object to show in the page
  final Medium medium;

  /// The constructor of ViewerPage
  ViewerPage(Medium medium) : medium = medium;

  @override
  Widget build(BuildContext context) {
    DateTime? date = medium.creationDate ?? medium.modifiedDate;
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          leading: IconButton(
            onPressed: () => Navigator.of(context).pop(),
            icon: Icon(Icons.arrow_back_ios),
          ),
          title: date != null ? Text(date.toLocal().toString()) : null,
        ),
        body: Container(
          alignment: Alignment.center,
          child: medium.mediumType == MediumType.image
              ? GestureDetector(
                  onTap: () async {
                    PhotoGallery.deleteMedium(mediumId: medium.id);
                  },
                  child: FadeInImage(
                    fit: BoxFit.cover,
                    placeholder: MemoryImage(kTransparentImage),
                    image: PhotoProvider(mediumId: medium.id),
                  ),
                )
              : VideoProvider(
                  mediumId: medium.id,
                ),
        ),
      ),
    );
  }
}

/// The video provider widget
class VideoProvider extends StatefulWidget {
  /// The identifier of medium
  final String mediumId;

  /// The constructor of VideoProvider
  const VideoProvider({
    required this.mediumId,
  });

  @override
  _VideoProviderState createState() => _VideoProviderState();
}

class _VideoProviderState extends State<VideoProvider> {
  VideoPlayerController? _controller;
  File? _file;

  @override
  void initState() {
    WidgetsBinding.instance.addPostFrameCallback((_) {
      initAsync();
    });
    super.initState();
  }

  Future<void> initAsync() async {
    try {
      _file = await PhotoGallery.getFile(mediumId: widget.mediumId);
      _controller = VideoPlayerController.file(_file!);
      _controller?.initialize().then((_) {
        // Ensure the first frame is shown after the video is initialized, even before the play button has been pressed.
        setState(() {});
      });
    } catch (e) {
      print("Failed : $e");
    }
  }

  @override
  Widget build(BuildContext context) {
    return _controller == null || !_controller!.value.isInitialized
        ? Container()
        : Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              AspectRatio(
                aspectRatio: _controller!.value.aspectRatio,
                child: VideoPlayer(_controller!),
              ),
              TextButton(
                onPressed: () {
                  setState(() {
                    _controller!.value.isPlaying ? _controller!.pause() : _controller!.play();
                  });
                },
                child: Icon(
                  _controller!.value.isPlaying ? Icons.pause : Icons.play_arrow,
                ),
              ),
            ],
          );
  }
}