Client/lib/widget/file_viewer.dart

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

import 'package:file_picker/file_picker.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:open_filex/open_filex.dart';
import 'package:photo_view/photo_view.dart';
import 'package:share_plus/share_plus.dart';
import 'package:syncfusion_flutter_pdfviewer/pdfviewer.dart';

import '../routing/app_routes.dart';
import '../state/app/modules/settings/bloc/settings_cubit.dart';
import 'info_dialog.dart';
import 'placeholder_view.dart';
import 'share_position_origin.dart';

class FileViewer extends StatefulWidget {
  final String path;
  final bool openExternal;
  const FileViewer({super.key, required this.path, this.openExternal = false});

  @override
  State<FileViewer> createState() => _FileViewerState();
}

enum FileViewingActions {
  openExternal,
  share,
  save
}

/// Workaround for a Syncfusion PDF viewer race: SfPdfViewer's internal
/// LayoutBuilder calls `localToGlobal` during build, which asserts when an
/// ancestor RenderTransform (from the page-push animation) is still mid-layout.
/// We wait for the route's enter animation to complete before mounting it.
class _DeferredPdfViewer extends StatefulWidget {
  const _DeferredPdfViewer({required this.path});
  final String path;

  @override
  State<_DeferredPdfViewer> createState() => _DeferredPdfViewerState();
}

class _DeferredPdfViewerState extends State<_DeferredPdfViewer> {
  bool _ready = false;
  Animation<double>? _routeAnimation;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    if (_ready || _routeAnimation != null) return;
    final animation = ModalRoute.of(context)?.animation;
    if (animation == null || animation.isCompleted) {
      _ready = true;
      return;
    }
    _routeAnimation = animation..addStatusListener(_onAnimationStatus);
  }

  void _onAnimationStatus(AnimationStatus status) {
    if (status == AnimationStatus.completed && mounted) {
      setState(() => _ready = true);
    }
  }

  @override
  void dispose() {
    _routeAnimation?.removeStatusListener(_onAnimationStatus);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    if (!_ready) {
      return const Center(child: CircularProgressIndicator());
    }
    return SfPdfViewer.file(File(widget.path));
  }
}

class _FileViewerState extends State<FileViewer> {
  PhotoViewController photoViewController = PhotoViewController();

  late SettingsCubit settings = context.read<SettingsCubit>();
  late bool openExternal;

  @override
  void initState() {
    openExternal = settings.val().fileViewSettings.alwaysOpenExternally || widget.openExternal;
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    AppBar appbar({List<Widget> actions = const []}) => AppBar(
        title: Text(widget.path.split('/').last),
        actions: [
          ...actions,
          PopupMenuButton<FileViewingActions>(
            onSelected: (value) async {
              switch(value) {
                case FileViewingActions.openExternal:
                  AppRoutes.openFileViewer(context, widget.path, openExternal: true);
                  break;
                case FileViewingActions.share:
                  unawaited(SharePlus.instance.share(
                    ShareParams(
                      files: [XFile(widget.path)],
                      sharePositionOrigin: SharePositionOrigin.get(context),
                    ),
                  ));
                  break;
                case FileViewingActions.save:
                  try {
                    final bytes = await File(widget.path).readAsBytes();
                    final saved = await FilePicker.saveFile(
                      fileName: widget.path.split('/').last,
                      bytes: bytes,
                    );
                    if (!context.mounted) return;
                    if (saved != null) InfoDialog.show(context, 'Datei gespeichert.');
                  } on Object catch (e) {
                    if (!context.mounted) return;
                    InfoDialog.show(context, 'Speichern fehlgeschlagen: $e', copyable: true, title: 'Fehler');
                  }
                  break;
              }
            },
            itemBuilder: (context) => <PopupMenuEntry<FileViewingActions>>[
              const PopupMenuItem(
                value: FileViewingActions.openExternal,
                child: ListTile(
                  leading: Icon(Icons.open_in_new),
                  title: Text('Extern öffnen'),
                  dense: true,
                ),
              ),
              const PopupMenuItem(
                value: FileViewingActions.share,
                child: ListTile(
                  leading: Icon(Icons.share_outlined),
                  title: Text('Teilen'),
                  dense: true,
                ),
              ),
              const PopupMenuItem(
                value: FileViewingActions.save,
                child: ListTile(
                  leading: Icon(Icons.save_alt_outlined),
                  title: Text('Speichern'),
                  dense: true,
                ),
              ),
            ],
          ),
        ],
      );

    switch(openExternal ? '' : widget.path.split('.').last.toLowerCase()) {
      case 'png':
      case 'jpg':
      case 'jpeg':
      case 'webp':
      case 'gif':
        return Scaffold(
            appBar: appbar(
                actions: [
                  IconButton(onPressed: () {
                    setState(() {
                      photoViewController.rotation += pi/2;
                    });
                  }, icon: const Icon(Icons.rotate_right)),
                ]
            ),
            backgroundColor: Colors.white,
            body: PhotoView(
              controller: photoViewController,
              maxScale: 3.0,
              minScale: 0.1,
              imageProvider: Image.file(File(widget.path)).image,
              backgroundDecoration: BoxDecoration(color: Theme.of(context).colorScheme.surface),
            )
        );


      case 'pdf':
        return Scaffold(
          appBar: appbar(),
          body: _DeferredPdfViewer(path: widget.path),
        );

      default:
        OpenFilex.open(widget.path).then((result) {
          if (!context.mounted) return;
          Navigator.of(context).pop();
          if(result.type != ResultType.done) {
            showDialog(context: context, builder: (context) => AlertDialog(
                content: Text(result.message),
              ));
          }
        });

        return PlaceholderView(
          text: 'Datei extern geöffnet',
          icon: Icons.open_in_new,
          button: TextButton(
            onPressed: () => Navigator.of(context).pop(),
            child: const Text('Zurück'),
          ),
        );
    }
  }
}