refactor: ui_services.dart to PdfExportViewModel for export functionality

integration_test/export_flow_test.dart

@@ -14,7 +14,7 @@ import 'package:pdf_signature/data/repositories/signature_card_repository.dart';
 import 'package:pdf_signature/data/repositories/document_repository.dart';
 import 'package:pdf_signature/domain/models/model.dart';
 import 'package:pdf_signature/ui/features/pdf/view_model/pdf_view_model.dart';
-import 'package:pdf_signature/ui/features/pdf/widgets/ui_services.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/pdf_export_view_model.dart';
 import 'package:pdf_signature/ui/features/pdf/widgets/pages_sidebar.dart';
 import 'package:pdf_signature/ui/features/pdf/widgets/pdf_screen.dart';
 import 'package:shared_preferences/shared_preferences.dart';
@@ -77,13 +77,16 @@ void main() {
           pdfViewModelProvider.overrideWith(
             (ref) => PdfViewModel(ref, useMockViewer: false),
           ),
-          exportServiceProvider.overrideWith((_) => fake),
+          pdfExportViewModelProvider.overrideWith(
-          savePathPickerProvider.overrideWith(
+            (ref) => PdfExportViewModel(
-            (_) => () async {
+              ref,
+              exporter: fake,
+              savePathPicker: () async {
                 final dir = Directory.systemTemp.createTempSync('pdfsig_');
                 return '${dir.path}/output.pdf';
               },
             ),
+          ),
         ],
         child: MaterialApp(
           localizationsDelegates: AppLocalizations.localizationsDelegates,
@@ -432,13 +435,18 @@ void main() {
           pdfViewModelProvider.overrideWith(
             (ref) => PdfViewModel(ref, useMockViewer: false),
           ),
-          exportServiceProvider.overrideWith((ref) => LightweightExporter()),
+          pdfExportViewModelProvider.overrideWith(
-          savePathPickerProvider.overrideWith(
+            (ref) => PdfExportViewModel(
-            (_) => () async {
+              ref,
-              final dir = Directory.systemTemp.createTempSync('pdfsig_after_');
+              exporter: LightweightExporter(),
+              savePathPicker: () async {
+                final dir = Directory.systemTemp.createTempSync(
+                  'pdfsig_after_',
+                );
                 return '${dir.path}/output-after-export.pdf';
               },
             ),
+          ),
         ],
         child: MaterialApp(
           localizationsDelegates: AppLocalizations.localizationsDelegates,

lib/ui/features/pdf/view_model/pdf_export_view_model.dart

@@ -0,0 +1,53 @@
+import 'package:file_selector/file_selector.dart' as fs;
+import 'package:flutter/foundation.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:pdf_signature/data/services/export_service.dart';
+
+/// ViewModel for export-related UI state and helpers.
+class PdfExportViewModel extends ChangeNotifier {
+  final Ref ref;
+  bool _exporting = false;
+
+  // Dependencies (injectable via constructor for tests)
+  final ExportService _exporter;
+  final Future<String?> Function() _savePathPicker;
+
+  PdfExportViewModel(
+    this.ref, {
+    ExportService? exporter,
+    Future<String?> Function()? savePathPicker,
+  }) : _exporter = exporter ?? ExportService(),
+       _savePathPicker = savePathPicker ?? _defaultSavePathPicker;
+
+  bool get exporting => _exporting;
+
+  void setExporting(bool value) {
+    if (_exporting == value) return;
+    _exporting = value;
+    notifyListeners();
+  }
+
+  /// Get the export service (overridable in tests via constructor).
+  ExportService get exporter => _exporter;
+
+  /// Show save dialog and return the chosen path (null if canceled).
+  Future<String?> pickSavePath() async {
+    return _savePathPicker();
+  }
+
+  static Future<String?> _defaultSavePathPicker() async {
+    final group = fs.XTypeGroup(label: 'PDF', extensions: ['pdf']);
+    final location = await fs.getSaveLocation(
+      acceptedTypeGroups: [group],
+      suggestedName: 'signed.pdf',
+      confirmButtonText: 'Save',
+    );
+    return location?.path; // null if user cancels
+  }
+}
+
+final pdfExportViewModelProvider = ChangeNotifierProvider<PdfExportViewModel>((
+  ref,
+) {
+  return PdfExportViewModel(ref);
+});

lib/ui/features/pdf/widgets/pdf_screen.dart

@@ -12,7 +12,7 @@ import 'pdf_toolbar.dart';
 import 'pdf_page_area.dart';
 import 'pages_sidebar.dart';
 import 'signatures_sidebar.dart';
-import 'ui_services.dart';
+import '../view_model/pdf_export_view_model.dart';
 import 'package:pdf_signature/utils/download.dart';
 import '../view_model/pdf_view_model.dart';
 
@@ -133,7 +133,7 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
   }
 
   Future<void> _saveSignedPdf() async {
-    ref.read(exportingProvider.notifier).state = true;
+    ref.read(pdfExportViewModelProvider.notifier).setExporting(true);
     try {
       final pdf = _viewModel.document;
       final messenger = ScaffoldMessenger.of(context);
@@ -145,7 +145,7 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
         );
         return;
       }
-      final exporter = ref.read(exportServiceProvider);
+      final exporter = ref.read(pdfExportViewModelProvider).exporter;
 
       // get DPI from preferences
       final targetDpi = ref.read(preferencesRepositoryProvider).exportDpi;
@@ -153,8 +153,7 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
       String? savedPath;
 
       if (!kIsWeb) {
-        final pick = ref.read(savePathPickerProvider);
+        final path = await ref.read(pdfExportViewModelProvider).pickSavePath();
-        final path = await pick();
         if (path == null || path.trim().isEmpty) return;
         final fullPath = _ensurePdfExtension(path.trim());
         savedPath = fullPath;
@@ -216,7 +215,7 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
         );
       }
     } finally {
-      ref.read(exportingProvider.notifier).state = false;
+      ref.read(pdfExportViewModelProvider.notifier).setExporting(false);
     }
   }
 
@@ -362,7 +361,7 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
   }
 
   Widget _buildScaffold(BuildContext context) {
-    final isExporting = ref.watch(exportingProvider);
+    final isExporting = ref.watch(pdfExportViewModelProvider).exporting;
     final l = AppLocalizations.of(context);
     return Scaffold(
       body: Padding(

lib/ui/features/pdf/widgets/signatures_sidebar.dart

@@ -4,7 +4,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:pdf_signature/l10n/app_localizations.dart';
 
 import '../../signature/widgets/signature_drawer.dart';
-import 'ui_services.dart';
+import '../view_model/pdf_export_view_model.dart';
 
 class SignaturesSidebar extends ConsumerWidget {
   const SignaturesSidebar({
@@ -21,7 +21,7 @@ class SignaturesSidebar extends ConsumerWidget {
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final l = AppLocalizations.of(context);
-    final isExporting = ref.watch(exportingProvider);
+    final isExporting = ref.watch(pdfExportViewModelProvider).exporting;
     return AbsorbPointer(
       absorbing: isExporting,
       child: Card(

lib/ui/features/pdf/widgets/ui_services.dart

@@ -1,23 +0,0 @@
-import 'package:file_selector/file_selector.dart' as fs;
-import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/data/services/export_service.dart';
-
-/// Global exporting flag used to disable parts of the UI during long tasks.
-final exportingProvider = StateProvider<bool>((ref) => false);
-
-/// Provider for the export service. Can be overridden in tests.
-final exportServiceProvider = Provider<ExportService>((ref) => ExportService());
-
-/// Provider for a function that picks a save path. Tests may override.
-final savePathPickerProvider = Provider<Future<String?> Function()>((ref) {
-  return () async {
-    // Desktop save dialog with PDF filter; mobile platforms may not support this.
-    final group = fs.XTypeGroup(label: 'PDF', extensions: ['pdf']);
-    final location = await fs.getSaveLocation(
-      acceptedTypeGroups: [group],
-      suggestedName: 'signed.pdf',
-      confirmButtonText: 'Save',
-    );
-    return location?.path; // null if user cancels
-  };
-});

test/features/_test_helper.dart

@@ -7,7 +7,7 @@ import 'package:shared_preferences/shared_preferences.dart';
 import 'package:pdf_signature/app.dart';
 import 'package:pdf_signature/data/repositories/preferences_repository.dart';
 import 'package:pdf_signature/data/repositories/document_repository.dart';
-import 'package:pdf_signature/ui/features/pdf/widgets/ui_services.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/pdf_export_view_model.dart';
 import 'package:pdf_signature/data/services/export_service.dart';
 import 'package:pdf_signature/domain/models/model.dart';
 
@@ -51,8 +51,13 @@ Future<ProviderContainer> pumpApp(
       pdfViewModelProvider.overrideWith(
         (ref) => PdfViewModel(ref, useMockViewer: true),
       ),
-      exportServiceProvider.overrideWith((ref) => fakeExport),
+      pdfExportViewModelProvider.overrideWith(
-      savePathPickerProvider.overrideWith((ref) => () async => 'out.pdf'),
+        (ref) => PdfExportViewModel(
+          ref,
+          exporter: fakeExport,
+          savePathPicker: () async => 'out.pdf',
+        ),
+      ),
     ],
   );
   await tester.pumpWidget(

test/widget/export_flow_test.dart

@@ -7,7 +7,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
 import 'package:pdf_signature/data/services/export_service.dart';
-import 'package:pdf_signature/ui/features/pdf/widgets/ui_services.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/pdf_export_view_model.dart';
 import 'package:pdf_signature/data/repositories/preferences_repository.dart';
 import 'package:pdf_signature/ui/features/pdf/view_model/pdf_view_model.dart';
 
@@ -62,9 +62,12 @@ void main() {
           pdfViewModelProvider.overrideWith(
             (ref) => PdfViewModel(ref, useMockViewer: true),
           ),
-          exportServiceProvider.overrideWith((_) => fake),
+          pdfExportViewModelProvider.overrideWith(
-          savePathPickerProvider.overrideWith(
+            (ref) => PdfExportViewModel(
-            (_) => () async => 'C:/tmp/output.pdf',
+              ref,
+              exporter: fake,
+              savePathPicker: () async => 'C:/tmp/output.pdf',
+            ),
           ),
         ],
         child: MaterialApp(

test/widget/helpers.dart

@@ -7,7 +7,7 @@ import 'package:image/image.dart' as img;
 
 import 'package:pdf_signature/ui/features/pdf/widgets/pdf_screen.dart';
 import 'package:pdf_signature/ui/features/pdf/view_model/pdf_view_model.dart';
-import 'package:pdf_signature/ui/features/pdf/widgets/ui_services.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/pdf_export_view_model.dart';
 import 'package:pdf_signature/data/repositories/document_repository.dart';
 import 'package:pdf_signature/data/repositories/signature_asset_repository.dart';
 import 'package:pdf_signature/data/repositories/signature_card_repository.dart';
@@ -26,7 +26,9 @@ Future<void> pumpWithOpenPdf(WidgetTester tester) async {
         pdfViewModelProvider.overrideWith(
           (ref) => PdfViewModel(ref, useMockViewer: true),
         ),
-        exportingProvider.overrideWith((ref) => false),
+        pdfExportViewModelProvider.overrideWith(
+          (ref) => PdfExportViewModel(ref),
+        ),
       ],
       child: MaterialApp(
         localizationsDelegates: AppLocalizations.localizationsDelegates,
@@ -398,7 +400,9 @@ Future<void> pumpWithOpenPdfAndSig(WidgetTester tester) async {
         pdfViewModelProvider.overrideWith(
           (ref) => PdfViewModel(ref, useMockViewer: true),
         ),
-        exportingProvider.overrideWith((ref) => false),
+        pdfExportViewModelProvider.overrideWith(
+          (ref) => PdfExportViewModel(ref),
+        ),
       ],
       child: MaterialApp(
         localizationsDelegates: AppLocalizations.localizationsDelegates,