Remote sync of webdav

lib/screens/cloud_folder_browser_screen.dart

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+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import '../services/app_state.dart';
+import '../services/cloud/cloud_storage_provider.dart';
+
+enum _BrowseRoot { myFiles, sharedWithMe }
+
+/// Lets the user navigate whichever cloud storage provider is connected —
+/// their own files, and (if the provider supports it) files others have
+/// shared with them — and pick a parent location. Confirming looks for (or
+/// creates) the `MO-Fuel-Tax-Back` folder under that location, so two
+/// people pointing at the same shared parent converge on the same app
+/// folder, regardless of which provider each of them is using.
+class CloudFolderBrowserScreen extends StatefulWidget {
+  const CloudFolderBrowserScreen({super.key});
+
+  @override
+  State<CloudFolderBrowserScreen> createState() => _CloudFolderBrowserScreenState();
+}
+
+class _CloudFolderBrowserScreenState extends State<CloudFolderBrowserScreen> {
+  late final CloudStorageSession _session;
+
+  _BrowseRoot _root = _BrowseRoot.myFiles;
+  final List<CloudFolder> _pathStack = [];
+
+  List<CloudFolder>? _folders;
+  bool _loading = true;
+  String? _error;
+  bool _confirming = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _session = context.read<AppState>().activeProvider!.beginSession();
+    _load();
+  }
+
+  @override
+  void dispose() {
+    _session.close();
+    super.dispose();
+  }
+
+  String get _rootLabel => _root == _BrowseRoot.myFiles ? 'My Files' : 'Shared with me';
+
+  /// The folder ID that "Use This Folder" would act on, or null if the
+  /// current view is a virtual listing (top-level "Shared with me") rather
+  /// than an actual folder.
+  String? get _currentFolderId {
+    if (_pathStack.isNotEmpty) return _pathStack.last.id;
+    if (_root == _BrowseRoot.myFiles) return 'root';
+    return null;
+  }
+
+  String get _breadcrumbPath =>
+      ([_rootLabel] + _pathStack.map((f) => f.name).toList()).join(' / ');
+
+  Future<void> _load() async {
+    setState(() {
+      _loading = true;
+      _error = null;
+    });
+
+    try {
+      List<CloudFolder> folders;
+      if (_pathStack.isNotEmpty) {
+        folders = await _session.listFolders(parentId: _pathStack.last.id);
+      } else if (_root == _BrowseRoot.myFiles) {
+        folders = await _session.listFolders(parentId: 'root');
+      } else {
+        folders = await _session.listFolders(sharedWithMe: true);
+      }
+      if (!mounted) return;
+      setState(() {
+        _folders = folders;
+        _loading = false;
+      });
+    } catch (e) {
+      if (!mounted) return;
+      setState(() {
+        _error = 'Could not load folders: $e';
+        _loading = false;
+      });
+    }
+  }
+
+  void _switchRoot(_BrowseRoot root) {
+    if (root == _root) return;
+    setState(() {
+      _root = root;
+      _pathStack.clear();
+    });
+    _load();
+  }
+
+  void _openFolder(CloudFolder folder) {
+    setState(() => _pathStack.add(folder));
+    _load();
+  }
+
+  void _goToBreadcrumb(int index) {
+    // index == -1 means the root label itself.
+    setState(() {
+      if (index < 0) {
+        _pathStack.clear();
+      } else {
+        _pathStack.removeRange(index + 1, _pathStack.length);
+      }
+    });
+    _load();
+  }
+
+  Future<void> _useThisFolder() async {
+    final parentId = _currentFolderId;
+    if (parentId == null) return;
+
+    setState(() => _confirming = true);
+    try {
+      await context.read<AppState>().chooseCloudFolder(
+            parentId: parentId,
+            breadcrumbPath: _breadcrumbPath,
+          );
+      if (mounted) Navigator.of(context).pop();
+    } catch (e) {
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text('Could not use this folder: $e')),
+        );
+      }
+    } finally {
+      if (mounted) setState(() => _confirming = false);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final providerName = context.read<AppState>().activeProvider!.displayName;
+    final canUseCurrentFolder = _currentFolderId != null;
+
+    return Scaffold(
+      appBar: AppBar(title: Text('Choose $providerName Folder')),
+      body: Column(
+        children: [
+          if (_session.supportsSharedWithMe)
+            SegmentedButton<_BrowseRoot>(
+              segments: const [
+                ButtonSegment(value: _BrowseRoot.myFiles, label: Text('My Files')),
+                ButtonSegment(value: _BrowseRoot.sharedWithMe, label: Text('Shared with me')),
+              ],
+              selected: {_root},
+              onSelectionChanged: (selection) => _switchRoot(selection.first),
+            ),
+          Padding(
+            padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
+            child: SingleChildScrollView(
+              scrollDirection: Axis.horizontal,
+              child: Row(
+                children: [
+                  TextButton(
+                    onPressed: () => _goToBreadcrumb(-1),
+                    child: Text(_rootLabel),
+                  ),
+                  for (var i = 0; i < _pathStack.length; i++) ...[
+                    const Icon(Icons.chevron_right, size: 18),
+                    TextButton(
+                      onPressed: () => _goToBreadcrumb(i),
+                      child: Text(_pathStack[i].name),
+                    ),
+                  ],
+                ],
+              ),
+            ),
+          ),
+          const Divider(height: 1),
+          Expanded(child: _buildBody()),
+        ],
+      ),
+      bottomNavigationBar: SafeArea(
+        child: Padding(
+          padding: const EdgeInsets.all(16),
+          child: FilledButton.icon(
+            onPressed: (!canUseCurrentFolder || _confirming) ? null : _useThisFolder,
+            icon: _confirming
+                ? const SizedBox(height: 16, width: 16, child: CircularProgressIndicator(strokeWidth: 2))
+                : const Icon(Icons.check),
+            label: Text('Use "$_breadcrumbPath"'),
+          ),
+        ),
+      ),
+    );
+  }
+
+  Widget _buildBody() {
+    if (_loading) {
+      return const Center(child: CircularProgressIndicator());
+    }
+    if (_error != null) {
+      return Center(child: Padding(padding: const EdgeInsets.all(24), child: Text(_error!)));
+    }
+    final folders = _folders ?? [];
+    if (folders.isEmpty) {
+      return const Center(child: Text('No folders here.'));
+    }
+    return ListView.builder(
+      itemCount: folders.length,
+      itemBuilder: (context, index) {
+        final folder = folders[index];
+        return ListTile(
+          leading: const Icon(Icons.folder_outlined),
+          title: Text(folder.name),
+          trailing: const Icon(Icons.chevron_right),
+          onTap: () => _openFolder(folder),
+        );
+      },
+    );
+  }
+}