split file_viewer into focused sub-widgets

lib/widget/file_viewer.dart

@@ -3,8 +3,6 @@ import 'dart:convert';
 import 'dart:io';
 import 'dart:math';
 
-import 'package:cached_network_image/cached_network_image.dart';
-import 'package:chewie/chewie.dart';
 import 'package:file_picker/file_picker.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
@@ -12,34 +10,20 @@ import 'package:flutter_svg/flutter_svg.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 'package:video_player/video_player.dart';
 
-import '../model/account_data.dart';
-import '../model/endpoint_data.dart';
 import '../routing/app_routes.dart';
 import '../share_intent/remote_file_ref.dart';
 import '../state/app/modules/settings/bloc/settings_cubit.dart';
 import 'app_progress_indicator.dart';
 import 'centered_leading.dart';
+import 'file_viewer/code_line.dart';
+import 'file_viewer/deferred_pdf_viewer.dart';
+import 'file_viewer/file_kind.dart';
+import 'file_viewer/media_player.dart';
+import 'file_viewer/unknown_preview_block.dart';
 import 'info_dialog.dart';
 import 'share_position_origin.dart';
 
-/// Nextcloud's `/index.php/core/preview` endpoint — returns a rasterized
-/// thumbnail for any file the server has a preview provider for (images,
-/// PDFs with the right backend, Office in some setups). Falls back to an
-/// HTTP 404 when no preview is available, which lets [CachedNetworkImage]
-/// trigger its `errorWidget`. Prefers `fileId` because the path variant
-/// is unreliable on some server configurations.
-String _ncPreviewUrl(RemoteFileRef remote, {int width = 1024}) {
-  final host = EndpointData().nextcloud().full();
-  final id = remote.fileId;
-  final selector = id != null
-      ? 'fileId=$id'
-      : 'file=${Uri.encodeQueryComponent(remote.path)}';
-  return 'https://$host/index.php/core/preview?$selector&x=$width&y=-1&a=1';
-}
-
 class FileViewer extends StatefulWidget {
   final String path;
   final bool openExternal;
@@ -61,133 +45,12 @@ class FileViewer extends StatefulWidget {
 
 enum FileViewingActions { openExternal, share, save, sendToChat, saveToCloud }
 
-enum _FileKind { image, svg, pdf, text, video, audio, unknown }
-
-const Set<String> _imageExtensions = {
-  'png',
-  'jpg',
-  'jpeg',
-  'webp',
-  'gif',
-  'bmp',
-  'wbmp',
-};
-
-const Set<String> _videoExtensions = {
-  'mp4',
-  'm4v',
-  'mov',
-  'webm',
-  'mkv',
-  '3gp',
-};
-
-/// ogg/opus/flac are Android-only; iOS init errors fall through to the
-/// "format not supported" message.
-const Set<String> _audioExtensions = {
-  'mp3',
-  'm4a',
-  'aac',
-  'wav',
-  'flac',
-  'ogg',
-  'oga',
-  'opus',
-};
-
-/// Unknown extensions still get a content sniff via [_looksLikeText].
-const Set<String> _textExtensions = {
-  'txt', 'md', 'markdown', 'rst', 'log',
-  'json', 'json5', 'xml', 'yaml', 'yml', 'toml',
-  'csv', 'tsv', 'tab',
-  'ini', 'conf', 'cfg', 'env', 'properties',
-  'html', 'htm', 'xhtml',
-  'css', 'scss', 'sass', 'less',
-  'js', 'mjs', 'cjs', 'ts', 'jsx', 'tsx',
-  'dart', 'java', 'kt', 'kts', 'groovy', 'scala', 'swift',
-  'py', 'rb', 'pl', 'lua', 'r',
-  'go', 'rs', 'zig',
-  'c', 'cpp', 'cc', 'cxx', 'h', 'hpp', 'cs', 'm', 'mm',
-  'php', 'sh', 'bash', 'zsh', 'fish', 'ps1', 'bat', 'cmd',
-  'sql', 'graphql', 'gql',
-  'gitignore', 'gitattributes', 'editorconfig', 'dockerignore',
-  'dockerfile', 'makefile', 'cmake',
-  'tex', 'bib',
-  'srt', 'vtt',
-};
-
-/// 8 KB sniff: NUL bytes or non-UTF-8 sequences disqualify.
-Future<bool> _looksLikeText(String path) async {
-  final file = File(path);
-  RandomAccessFile? raf;
-  try {
-    final length = await file.length();
-    if (length == 0) return true;
-    raf = await file.open();
-    final sample = await raf.read(min(length, 8192));
-    if (sample.contains(0)) return false;
-    utf8.decode(sample);
-    return true;
-  } on Object {
-    return false;
-  } finally {
-    await raf?.close();
-  }
-}
-
-/// SfPdfViewer asserts on `localToGlobal` if mounted during the page-push
-/// animation. Defer until the route enter animation completes.
-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: AppProgressIndicator.large());
-    }
-    return SfPdfViewer.file(File(widget.path));
-  }
-}
-
 class _FileViewerState extends State<FileViewer> {
   final PhotoViewController photoViewController = PhotoViewController();
 
   late SettingsCubit settings = context.read<SettingsCubit>();
   late bool openExternal;
-  Future<_FileKind>? _fileKind;
+  Future<FileKind>? _fileKind;
 
   @override
   void initState() {
@@ -200,7 +63,7 @@ class _FileViewerState extends State<FileViewer> {
         (_) => _openExternallyAndPop(),
       );
     } else {
-      _fileKind = _detectKind();
+      _fileKind = detectFileKind(widget.path);
     }
   }
 
@@ -219,18 +82,6 @@ class _FileViewerState extends State<FileViewer> {
     super.dispose();
   }
 
-  Future<_FileKind> _detectKind() async {
-    final ext = widget.path.split('.').last.toLowerCase();
-    if (_imageExtensions.contains(ext)) return _FileKind.image;
-    if (ext == 'svg') return _FileKind.svg;
-    if (ext == 'pdf') return _FileKind.pdf;
-    if (_videoExtensions.contains(ext)) return _FileKind.video;
-    if (_audioExtensions.contains(ext)) return _FileKind.audio;
-    if (_textExtensions.contains(ext)) return _FileKind.text;
-    if (await _looksLikeText(widget.path)) return _FileKind.text;
-    return _FileKind.unknown;
-  }
-
   Future<void> _handleAction(FileViewingActions value) async {
     switch (value) {
       case FileViewingActions.openExternal:
@@ -360,7 +211,7 @@ class _FileViewerState extends State<FileViewer> {
         body: const Center(child: AppProgressIndicator.large()),
       );
     }
-    return FutureBuilder<_FileKind>(
+    return FutureBuilder<FileKind>(
       future: _fileKind,
       builder: (context, snapshot) {
         if (!snapshot.hasData) {
@@ -370,19 +221,19 @@ class _FileViewerState extends State<FileViewer> {
           );
         }
         switch (snapshot.data!) {
-          case _FileKind.image:
+          case FileKind.image:
             return _buildImageView();
-          case _FileKind.svg:
+          case FileKind.svg:
             return _buildSvgView();
-          case _FileKind.pdf:
+          case FileKind.pdf:
             return _buildPdfView();
-          case _FileKind.video:
+          case FileKind.video:
             return _buildVideoView();
-          case _FileKind.audio:
+          case FileKind.audio:
             return _buildAudioView();
-          case _FileKind.text:
+          case FileKind.text:
             return _buildTextView();
-          case _FileKind.unknown:
+          case FileKind.unknown:
             return _buildUnknownView();
         }
       },
@@ -431,17 +282,17 @@ class _FileViewerState extends State<FileViewer> {
   );
 
   Widget _buildPdfView() =>
-      Scaffold(appBar: _appbar(), body: _DeferredPdfViewer(path: widget.path));
+      Scaffold(appBar: _appbar(), body: DeferredPdfViewer(path: widget.path));
 
   Widget _buildVideoView() => Scaffold(
     appBar: _appbar(),
     backgroundColor: Colors.black,
-    body: _MediaPlayer(path: widget.path, isAudio: false),
+    body: MediaPlayer(path: widget.path, isAudio: false),
   );
 
   Widget _buildAudioView() => Scaffold(
     appBar: _appbar(),
-    body: _MediaPlayer(
+    body: MediaPlayer(
       path: widget.path,
       isAudio: true,
       filename: widget.path.split('/').last,
@@ -485,7 +336,7 @@ class _FileViewerState extends State<FileViewer> {
                   ),
                 SliverList.builder(
                   itemCount: lines.length,
-                  itemBuilder: (context, i) => _CodeLine(
+                  itemBuilder: (context, i) => CodeLine(
                     number: i + 1,
                     text: lines[i],
                     gutterWidth: gutterWidth,
@@ -515,7 +366,7 @@ class _FileViewerState extends State<FileViewer> {
           padding: const EdgeInsets.symmetric(horizontal: 24),
           child: Column(
             children: [
-              _UnknownPreviewBlock(remoteFile: widget.remoteFile),
+              UnknownPreviewBlock(remoteFile: widget.remoteFile),
               const SizedBox(height: 16),
               Text(
                 widget.path.split('/').last,
@@ -596,313 +447,3 @@ class _TextPayload {
   final bool truncated;
   const _TextPayload({required this.content, required this.truncated});
 }
-
-/// Header block for the "Vorschau nicht verfügbar" screen.
-///
-/// Two visual modes — kept layout-equivalent so the screen looks identical
-/// whether the server already said "no preview" or the probe failed late:
-///   * **No preview available** (server said no, no remoteFile, or probe
-///     errored): compact "file icon + 'Vorschau nicht verfügbar' text".
-///   * **Preview rendering / loaded**: mid-sized thumbnail without text.
-class _UnknownPreviewBlock extends StatefulWidget {
-  final RemoteFileRef? remoteFile;
-  const _UnknownPreviewBlock({required this.remoteFile});
-
-  @override
-  State<_UnknownPreviewBlock> createState() => _UnknownPreviewBlockState();
-}
-
-class _UnknownPreviewBlockState extends State<_UnknownPreviewBlock> {
-  static const double _previewSize = 180;
-  bool _failed = false;
-
-  Widget _compact(ThemeData theme) => Column(
-    mainAxisSize: MainAxisSize.min,
-    children: [
-      const Icon(Icons.insert_drive_file_outlined, size: 60),
-      const SizedBox(height: 16),
-      Text(
-        'Vorschau nicht verfügbar',
-        style: theme.textTheme.titleMedium,
-        textAlign: TextAlign.center,
-      ),
-    ],
-  );
-
-  @override
-  Widget build(BuildContext context) {
-    final theme = Theme.of(context);
-    final remote = widget.remoteFile;
-    final canProbe =
-        remote != null &&
-        remote.hasPreview != false &&
-        remote.fileId != null &&
-        !_failed;
-    if (!canProbe) return _compact(theme);
-    return SizedBox(
-      width: _previewSize,
-      height: _previewSize,
-      child: CachedNetworkImage(
-        httpHeaders: AccountData().authHeaders(),
-        imageUrl: _ncPreviewUrl(remote, width: 360),
-        fadeInDuration: Duration.zero,
-        fadeOutDuration: Duration.zero,
-        // Late probe failure: re-render into the compact layout so the
-        // screen doesn't keep a 180×180 box around a tiny icon. Deferred
-        // to the next frame because setState during build is illegal.
-        errorListener: (_) {
-          if (!mounted) return;
-          WidgetsBinding.instance.addPostFrameCallback((_) {
-            if (mounted) setState(() => _failed = true);
-          });
-        },
-        placeholder: (_, _) =>
-            const Center(child: AppProgressIndicator.large()),
-        // Briefly empty while the post-frame setState swaps layouts.
-        errorWidget: (_, _, _) => const SizedBox.shrink(),
-        imageBuilder: (_, imageProvider) => ClipRRect(
-          borderRadius: BorderRadius.circular(8),
-          child: Image(
-            image: imageProvider,
-            fit: BoxFit.contain,
-            width: _previewSize,
-            height: _previewSize,
-          ),
-        ),
-      ),
-    );
-  }
-}
-
-class _MediaPlayer extends StatefulWidget {
-  final String path;
-  final bool isAudio;
-  final String? filename;
-  const _MediaPlayer({
-    required this.path,
-    required this.isAudio,
-    this.filename,
-  });
-
-  @override
-  State<_MediaPlayer> createState() => _MediaPlayerState();
-}
-
-class _MediaPlayerState extends State<_MediaPlayer> {
-  VideoPlayerController? _video;
-  ChewieController? _chewie;
-  Object? _initError;
-
-  @override
-  void initState() {
-    super.initState();
-    _initialize();
-  }
-
-  Future<void> _initialize() async {
-    final controller = VideoPlayerController.file(File(widget.path));
-    try {
-      await controller.initialize();
-    } on Object catch (e) {
-      await controller.dispose();
-      if (!mounted) return;
-      setState(() => _initError = e);
-      return;
-    }
-    if (!mounted) {
-      await controller.dispose();
-      return;
-    }
-    if (widget.isAudio) {
-      controller.addListener(_onAudioTick);
-      setState(() => _video = controller);
-    } else {
-      setState(() {
-        _video = controller;
-        _chewie = ChewieController(
-          videoPlayerController: controller,
-          autoPlay: false,
-          looping: false,
-          allowFullScreen: true,
-          allowPlaybackSpeedChanging: true,
-        );
-      });
-    }
-  }
-
-  void _onAudioTick() {
-    if (mounted) setState(() {});
-  }
-
-  @override
-  void dispose() {
-    _video?.removeListener(_onAudioTick);
-    _chewie?.dispose();
-    _video?.dispose();
-    super.dispose();
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    if (_initError != null) {
-      return Center(
-        child: Padding(
-          padding: const EdgeInsets.all(24),
-          child: Column(
-            mainAxisAlignment: MainAxisAlignment.center,
-            children: [
-              const Icon(Icons.error_outline, size: 48),
-              const SizedBox(height: 12),
-              Text(
-                widget.isAudio
-                    ? 'Audio kann nicht abgespielt werden'
-                    : 'Video kann nicht abgespielt werden',
-                style: Theme.of(context).textTheme.titleMedium,
-                textAlign: TextAlign.center,
-              ),
-              const SizedBox(height: 8),
-              Text(
-                'Format wird auf diesem Gerät nicht unterstützt. Über das Menü kannst du die Datei in einer anderen App öffnen.',
-                style: Theme.of(context).textTheme.bodySmall,
-                textAlign: TextAlign.center,
-              ),
-            ],
-          ),
-        ),
-      );
-    }
-    if (_video == null) {
-      return const Center(child: AppProgressIndicator.large());
-    }
-    if (widget.isAudio) {
-      return _AudioControls(
-        controller: _video!,
-        filename: widget.filename ?? '',
-      );
-    }
-    return Chewie(controller: _chewie!);
-  }
-}
-
-class _AudioControls extends StatelessWidget {
-  final VideoPlayerController controller;
-  final String filename;
-  const _AudioControls({required this.controller, required this.filename});
-
-  String _format(Duration d) {
-    final m = d.inMinutes.remainder(60).toString().padLeft(2, '0');
-    final s = d.inSeconds.remainder(60).toString().padLeft(2, '0');
-    if (d.inHours > 0) return '${d.inHours}:$m:$s';
-    return '$m:$s';
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    final value = controller.value;
-    final duration = value.duration;
-    final position = value.position;
-    final maxMs = duration.inMilliseconds == 0 ? 1 : duration.inMilliseconds;
-    final posMs = position.inMilliseconds.clamp(0, maxMs).toDouble();
-    return Center(
-      child: Padding(
-        padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 32),
-        child: Column(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: [
-            Icon(
-              Icons.audiotrack,
-              size: 96,
-              color: Theme.of(context).colorScheme.primary,
-            ),
-            const SizedBox(height: 24),
-            Text(
-              filename,
-              style: Theme.of(context).textTheme.titleMedium,
-              textAlign: TextAlign.center,
-            ),
-            const SizedBox(height: 32),
-            Slider(
-              min: 0,
-              max: maxMs.toDouble(),
-              value: posMs,
-              onChanged: (v) =>
-                  controller.seekTo(Duration(milliseconds: v.toInt())),
-            ),
-            Padding(
-              padding: const EdgeInsets.symmetric(horizontal: 16),
-              child: Row(
-                mainAxisAlignment: MainAxisAlignment.spaceBetween,
-                children: [
-                  Text(
-                    _format(position),
-                    style: Theme.of(context).textTheme.bodySmall,
-                  ),
-                  Text(
-                    _format(duration),
-                    style: Theme.of(context).textTheme.bodySmall,
-                  ),
-                ],
-              ),
-            ),
-            const SizedBox(height: 24),
-            FloatingActionButton(
-              heroTag: 'audioPlayPause',
-              onPressed: () {
-                if (value.isPlaying) {
-                  controller.pause();
-                } else {
-                  controller.play();
-                }
-              },
-              child: Icon(value.isPlaying ? Icons.pause : Icons.play_arrow),
-            ),
-          ],
-        ),
-      ),
-    );
-  }
-}
-
-class _CodeLine extends StatelessWidget {
-  final int number;
-  final String text;
-  final double gutterWidth;
-  const _CodeLine({
-    required this.number,
-    required this.text,
-    required this.gutterWidth,
-  });
-
-  static const TextStyle _codeStyle = TextStyle(
-    fontFamily: 'monospace',
-    fontSize: 13,
-    height: 1.4,
-  );
-
-  @override
-  Widget build(BuildContext context) {
-    final theme = Theme.of(context);
-    final isEven = number.isEven;
-    return Container(
-      color: isEven ? theme.colorScheme.surfaceContainerLow : null,
-      padding: const EdgeInsets.only(left: 4, right: 12),
-      child: Row(
-        crossAxisAlignment: CrossAxisAlignment.start,
-        children: [
-          SelectionContainer.disabled(
-            child: SizedBox(
-              width: gutterWidth,
-              child: Text(
-                '$number',
-                textAlign: TextAlign.right,
-                style: _codeStyle.copyWith(color: theme.hintColor),
-              ),
-            ),
-          ),
-          const SizedBox(width: 8),
-          Expanded(child: Text(text.isEmpty ? ' ' : text, style: _codeStyle)),
-        ],
-      ),
-    );
-  }
-}

lib/widget/file_viewer/code_line.dart

@@ -0,0 +1,48 @@
+import 'package:flutter/material.dart';
+
+/// A single line of the text/code viewer: a right-aligned, non-selectable line
+/// number gutter plus the selectable line content, with zebra striping.
+class CodeLine extends StatelessWidget {
+  final int number;
+  final String text;
+  final double gutterWidth;
+  const CodeLine({
+    super.key,
+    required this.number,
+    required this.text,
+    required this.gutterWidth,
+  });
+
+  static const TextStyle _codeStyle = TextStyle(
+    fontFamily: 'monospace',
+    fontSize: 13,
+    height: 1.4,
+  );
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final isEven = number.isEven;
+    return Container(
+      color: isEven ? theme.colorScheme.surfaceContainerLow : null,
+      padding: const EdgeInsets.only(left: 4, right: 12),
+      child: Row(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          SelectionContainer.disabled(
+            child: SizedBox(
+              width: gutterWidth,
+              child: Text(
+                '$number',
+                textAlign: TextAlign.right,
+                style: _codeStyle.copyWith(color: theme.hintColor),
+              ),
+            ),
+          ),
+          const SizedBox(width: 8),
+          Expanded(child: Text(text.isEmpty ? ' ' : text, style: _codeStyle)),
+        ],
+      ),
+    );
+  }
+}

lib/widget/file_viewer/deferred_pdf_viewer.dart

@@ -0,0 +1,53 @@
+import 'dart:io';
+
+import 'package:flutter/material.dart';
+import 'package:syncfusion_flutter_pdfviewer/pdfviewer.dart';
+
+import '../app_progress_indicator.dart';
+
+/// SfPdfViewer asserts on `localToGlobal` if mounted during the page-push
+/// animation. Defer until the route enter animation completes.
+class DeferredPdfViewer extends StatefulWidget {
+  const DeferredPdfViewer({super.key, 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: AppProgressIndicator.large());
+    }
+    return SfPdfViewer.file(File(widget.path));
+  }
+}

lib/widget/file_viewer/file_kind.dart

@@ -0,0 +1,92 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+import 'dart:math';
+
+enum FileKind { image, svg, pdf, text, video, audio, unknown }
+
+const Set<String> _imageExtensions = {
+  'png',
+  'jpg',
+  'jpeg',
+  'webp',
+  'gif',
+  'bmp',
+  'wbmp',
+};
+
+const Set<String> _videoExtensions = {
+  'mp4',
+  'm4v',
+  'mov',
+  'webm',
+  'mkv',
+  '3gp',
+};
+
+/// ogg/opus/flac are Android-only; iOS init errors fall through to the
+/// "format not supported" message.
+const Set<String> _audioExtensions = {
+  'mp3',
+  'm4a',
+  'aac',
+  'wav',
+  'flac',
+  'ogg',
+  'oga',
+  'opus',
+};
+
+/// Unknown extensions still get a content sniff via [_looksLikeText].
+const Set<String> _textExtensions = {
+  'txt', 'md', 'markdown', 'rst', 'log',
+  'json', 'json5', 'xml', 'yaml', 'yml', 'toml',
+  'csv', 'tsv', 'tab',
+  'ini', 'conf', 'cfg', 'env', 'properties',
+  'html', 'htm', 'xhtml',
+  'css', 'scss', 'sass', 'less',
+  'js', 'mjs', 'cjs', 'ts', 'jsx', 'tsx',
+  'dart', 'java', 'kt', 'kts', 'groovy', 'scala', 'swift',
+  'py', 'rb', 'pl', 'lua', 'r',
+  'go', 'rs', 'zig',
+  'c', 'cpp', 'cc', 'cxx', 'h', 'hpp', 'cs', 'm', 'mm',
+  'php', 'sh', 'bash', 'zsh', 'fish', 'ps1', 'bat', 'cmd',
+  'sql', 'graphql', 'gql',
+  'gitignore', 'gitattributes', 'editorconfig', 'dockerignore',
+  'dockerfile', 'makefile', 'cmake',
+  'tex', 'bib',
+  'srt', 'vtt',
+};
+
+/// Detects the [FileKind] of the file at [path] from its extension, falling
+/// back to an 8 KB content sniff ([_looksLikeText]) for unknown extensions.
+Future<FileKind> detectFileKind(String path) async {
+  final ext = path.split('.').last.toLowerCase();
+  if (_imageExtensions.contains(ext)) return FileKind.image;
+  if (ext == 'svg') return FileKind.svg;
+  if (ext == 'pdf') return FileKind.pdf;
+  if (_videoExtensions.contains(ext)) return FileKind.video;
+  if (_audioExtensions.contains(ext)) return FileKind.audio;
+  if (_textExtensions.contains(ext)) return FileKind.text;
+  if (await _looksLikeText(path)) return FileKind.text;
+  return FileKind.unknown;
+}
+
+/// 8 KB sniff: NUL bytes or non-UTF-8 sequences disqualify.
+Future<bool> _looksLikeText(String path) async {
+  final file = File(path);
+  RandomAccessFile? raf;
+  try {
+    final length = await file.length();
+    if (length == 0) return true;
+    raf = await file.open();
+    final sample = await raf.read(min(length, 8192));
+    if (sample.contains(0)) return false;
+    utf8.decode(sample);
+    return true;
+  } on Object {
+    return false;
+  } finally {
+    await raf?.close();
+  }
+}

lib/widget/file_viewer/media_player.dart

@@ -0,0 +1,200 @@
+import 'dart:io';
+
+import 'package:chewie/chewie.dart';
+import 'package:flutter/material.dart';
+import 'package:video_player/video_player.dart';
+
+import '../app_progress_indicator.dart';
+
+/// Plays a local video (via Chewie) or audio file (via [_AudioControls]).
+/// Reports an inline "format not supported" message when the platform can't
+/// initialize the file.
+class MediaPlayer extends StatefulWidget {
+  final String path;
+  final bool isAudio;
+  final String? filename;
+  const MediaPlayer({
+    super.key,
+    required this.path,
+    required this.isAudio,
+    this.filename,
+  });
+
+  @override
+  State<MediaPlayer> createState() => _MediaPlayerState();
+}
+
+class _MediaPlayerState extends State<MediaPlayer> {
+  VideoPlayerController? _video;
+  ChewieController? _chewie;
+  Object? _initError;
+
+  @override
+  void initState() {
+    super.initState();
+    _initialize();
+  }
+
+  Future<void> _initialize() async {
+    final controller = VideoPlayerController.file(File(widget.path));
+    try {
+      await controller.initialize();
+    } on Object catch (e) {
+      await controller.dispose();
+      if (!mounted) return;
+      setState(() => _initError = e);
+      return;
+    }
+    if (!mounted) {
+      await controller.dispose();
+      return;
+    }
+    if (widget.isAudio) {
+      controller.addListener(_onAudioTick);
+      setState(() => _video = controller);
+    } else {
+      setState(() {
+        _video = controller;
+        _chewie = ChewieController(
+          videoPlayerController: controller,
+          autoPlay: false,
+          looping: false,
+          allowFullScreen: true,
+          allowPlaybackSpeedChanging: true,
+        );
+      });
+    }
+  }
+
+  void _onAudioTick() {
+    if (mounted) setState(() {});
+  }
+
+  @override
+  void dispose() {
+    _video?.removeListener(_onAudioTick);
+    _chewie?.dispose();
+    _video?.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (_initError != null) {
+      return Center(
+        child: Padding(
+          padding: const EdgeInsets.all(24),
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: [
+              const Icon(Icons.error_outline, size: 48),
+              const SizedBox(height: 12),
+              Text(
+                widget.isAudio
+                    ? 'Audio kann nicht abgespielt werden'
+                    : 'Video kann nicht abgespielt werden',
+                style: Theme.of(context).textTheme.titleMedium,
+                textAlign: TextAlign.center,
+              ),
+              const SizedBox(height: 8),
+              Text(
+                'Format wird auf diesem Gerät nicht unterstützt. Über das Menü kannst du die Datei in einer anderen App öffnen.',
+                style: Theme.of(context).textTheme.bodySmall,
+                textAlign: TextAlign.center,
+              ),
+            ],
+          ),
+        ),
+      );
+    }
+    if (_video == null) {
+      return const Center(child: AppProgressIndicator.large());
+    }
+    if (widget.isAudio) {
+      return _AudioControls(
+        controller: _video!,
+        filename: widget.filename ?? '',
+      );
+    }
+    return Chewie(controller: _chewie!);
+  }
+}
+
+class _AudioControls extends StatelessWidget {
+  final VideoPlayerController controller;
+  final String filename;
+  const _AudioControls({required this.controller, required this.filename});
+
+  String _format(Duration d) {
+    final m = d.inMinutes.remainder(60).toString().padLeft(2, '0');
+    final s = d.inSeconds.remainder(60).toString().padLeft(2, '0');
+    if (d.inHours > 0) return '${d.inHours}:$m:$s';
+    return '$m:$s';
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final value = controller.value;
+    final duration = value.duration;
+    final position = value.position;
+    final maxMs = duration.inMilliseconds == 0 ? 1 : duration.inMilliseconds;
+    final posMs = position.inMilliseconds.clamp(0, maxMs).toDouble();
+    return Center(
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 32),
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            Icon(
+              Icons.audiotrack,
+              size: 96,
+              color: Theme.of(context).colorScheme.primary,
+            ),
+            const SizedBox(height: 24),
+            Text(
+              filename,
+              style: Theme.of(context).textTheme.titleMedium,
+              textAlign: TextAlign.center,
+            ),
+            const SizedBox(height: 32),
+            Slider(
+              min: 0,
+              max: maxMs.toDouble(),
+              value: posMs,
+              onChanged: (v) =>
+                  controller.seekTo(Duration(milliseconds: v.toInt())),
+            ),
+            Padding(
+              padding: const EdgeInsets.symmetric(horizontal: 16),
+              child: Row(
+                mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                children: [
+                  Text(
+                    _format(position),
+                    style: Theme.of(context).textTheme.bodySmall,
+                  ),
+                  Text(
+                    _format(duration),
+                    style: Theme.of(context).textTheme.bodySmall,
+                  ),
+                ],
+              ),
+            ),
+            const SizedBox(height: 24),
+            FloatingActionButton(
+              heroTag: 'audioPlayPause',
+              onPressed: () {
+                if (value.isPlaying) {
+                  controller.pause();
+                } else {
+                  controller.play();
+                }
+              },
+              child: Icon(value.isPlaying ? Icons.pause : Icons.play_arrow),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

lib/widget/file_viewer/unknown_preview_block.dart

@@ -0,0 +1,99 @@
+import 'package:cached_network_image/cached_network_image.dart';
+import 'package:flutter/material.dart';
+
+import '../../model/account_data.dart';
+import '../../model/endpoint_data.dart';
+import '../../share_intent/remote_file_ref.dart';
+import '../app_progress_indicator.dart';
+
+/// Nextcloud's `/index.php/core/preview` endpoint — returns a rasterized
+/// thumbnail for any file the server has a preview provider for (images,
+/// PDFs with the right backend, Office in some setups). Falls back to an
+/// HTTP 404 when no preview is available, which lets [CachedNetworkImage]
+/// trigger its `errorWidget`. Prefers `fileId` because the path variant
+/// is unreliable on some server configurations.
+String _ncPreviewUrl(RemoteFileRef remote, {int width = 1024}) {
+  final host = EndpointData().nextcloud().full();
+  final id = remote.fileId;
+  final selector = id != null
+      ? 'fileId=$id'
+      : 'file=${Uri.encodeQueryComponent(remote.path)}';
+  return 'https://$host/index.php/core/preview?$selector&x=$width&y=-1&a=1';
+}
+
+/// Header block for the "Vorschau nicht verfügbar" screen.
+///
+/// Two visual modes — kept layout-equivalent so the screen looks identical
+/// whether the server already said "no preview" or the probe failed late:
+///   * **No preview available** (server said no, no remoteFile, or probe
+///     errored): compact "file icon + 'Vorschau nicht verfügbar' text".
+///   * **Preview rendering / loaded**: mid-sized thumbnail without text.
+class UnknownPreviewBlock extends StatefulWidget {
+  final RemoteFileRef? remoteFile;
+  const UnknownPreviewBlock({super.key, required this.remoteFile});
+
+  @override
+  State<UnknownPreviewBlock> createState() => _UnknownPreviewBlockState();
+}
+
+class _UnknownPreviewBlockState extends State<UnknownPreviewBlock> {
+  static const double _previewSize = 180;
+  bool _failed = false;
+
+  Widget _compact(ThemeData theme) => Column(
+    mainAxisSize: MainAxisSize.min,
+    children: [
+      const Icon(Icons.insert_drive_file_outlined, size: 60),
+      const SizedBox(height: 16),
+      Text(
+        'Vorschau nicht verfügbar',
+        style: theme.textTheme.titleMedium,
+        textAlign: TextAlign.center,
+      ),
+    ],
+  );
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final remote = widget.remoteFile;
+    final canProbe =
+        remote != null &&
+        remote.hasPreview != false &&
+        remote.fileId != null &&
+        !_failed;
+    if (!canProbe) return _compact(theme);
+    return SizedBox(
+      width: _previewSize,
+      height: _previewSize,
+      child: CachedNetworkImage(
+        httpHeaders: AccountData().authHeaders(),
+        imageUrl: _ncPreviewUrl(remote, width: 360),
+        fadeInDuration: Duration.zero,
+        fadeOutDuration: Duration.zero,
+        // Late probe failure: re-render into the compact layout so the
+        // screen doesn't keep a 180×180 box around a tiny icon. Deferred
+        // to the next frame because setState during build is illegal.
+        errorListener: (_) {
+          if (!mounted) return;
+          WidgetsBinding.instance.addPostFrameCallback((_) {
+            if (mounted) setState(() => _failed = true);
+          });
+        },
+        placeholder: (_, _) =>
+            const Center(child: AppProgressIndicator.large()),
+        // Briefly empty while the post-frame setState swaps layouts.
+        errorWidget: (_, _, _) => const SizedBox.shrink(),
+        imageBuilder: (_, imageProvider) => ClipRRect(
+          borderRadius: BorderRadius.circular(8),
+          child: Image(
+            image: imageProvider,
+            fit: BoxFit.contain,
+            width: _previewSize,
+            height: _previewSize,
+          ),
+        ),
+      ),
+    );
+  }
+}