Implement offline mode

lib/features/home/home_page.dart

@@ -6,6 +6,7 @@ import 'package:sheetless/core/models/config.dart';
 import 'package:sheetless/core/models/sheet.dart';
 import 'package:sheetless/core/services/api_client.dart';
 import 'package:sheetless/core/services/storage_service.dart';
+import 'package:sheetless/core/services/sync_service.dart';
 
 import '../../app.dart';
 import '../auth/login_page.dart';
@@ -34,8 +35,11 @@ class _HomePageState extends State<HomePage> with RouteAware {
   final _storageService = StorageService();
 
   ApiClient? _apiClient;
-  late Future<List<Sheet>> _sheetsFuture;
+  SyncService? _syncService;
+  late Future<SyncResult> _syncFuture;
+  List<Sheet> _sheets = [];
   bool _isShuffling = false;
+  bool _isOnline = true;
   String? _appName;
   String? _appVersion;
 
@@ -52,7 +56,7 @@ class _HomePageState extends State<HomePage> with RouteAware {
     });
 
     _loadAppInfo();
-    _sheetsFuture = _loadSheets();
+    _syncFuture = _loadSheets();
   }
 
   @override
@@ -90,19 +94,29 @@ class _HomePageState extends State<HomePage> with RouteAware {
     });
   }
 
-  Future<List<Sheet>> _loadSheets() async {
+  Future<SyncResult> _loadSheets() async {
     final url = await _storageService.readSecure(SecureStorageKey.url);
     final jwt = await _storageService.readSecure(SecureStorageKey.jwt);
 
     _apiClient = ApiClient(baseUrl: url!, token: jwt);
+    _syncService = SyncService(
+      apiClient: _apiClient!,
+      storageService: _storageService,
+    );
 
-    final sheets = await _apiClient!.fetchSheets();
-    _log.info('${sheets.length} sheets fetched');
+    // Perform sync (fetches sheets, uploads pending changes/annotations)
+    final result = await _syncService!.sync();
+    _log.info(
+      '${result.sheets.length} sheets loaded (online: ${result.isOnline}, '
+      'changes synced: ${result.changesSynced}, '
+      'annotations synced: ${result.annotationsSynced})',
+    );
 
-    final sortedSheets = await _sortSheetsByRecency(sheets);
-    _log.info('${sortedSheets.length} sheets sorted');
+    // Sort and store sheets
+    _sheets = await _sortSheetsByRecency(result.sheets);
+    _isOnline = result.isOnline;
 
-    return sortedSheets;
+    return result;
   }
 
   Future<List<Sheet>> _sortSheetsByRecency(List<Sheet> sheets) async {
@@ -128,7 +142,7 @@ class _HomePageState extends State<HomePage> with RouteAware {
 
   Future<void> _refreshSheets() async {
     setState(() {
-      _sheetsFuture = _loadSheets();
+      _syncFuture = _loadSheets();
     });
   }
 
@@ -137,12 +151,10 @@ class _HomePageState extends State<HomePage> with RouteAware {
   // ---------------------------------------------------------------------------
 
   void _handleShuffleChanged(bool enabled) async {
-    final sheets = await _sheetsFuture;
-
     if (enabled) {
-      sheets.shuffle();
+      _sheets.shuffle();
     } else {
-      await _sortSheetsByRecency(sheets);
+      await _sortSheetsByRecency(_sheets);
     }
 
     setState(() => _isShuffling = enabled);
@@ -181,7 +193,16 @@ class _HomePageState extends State<HomePage> with RouteAware {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      appBar: AppBar(title: const Text('Sheetless')),
+      appBar: AppBar(
+        title: const Text('Sheetless'),
+        actions: [
+          if (!_isOnline)
+            const Padding(
+              padding: EdgeInsets.only(right: 8),
+              child: Icon(Icons.cloud_off, color: Colors.orange),
+            ),
+        ],
+      ),
       endDrawer: AppDrawer(
         isShuffling: _isShuffling,
         onShuffleChanged: _handleShuffleChanged,
@@ -194,8 +215,8 @@ class _HomePageState extends State<HomePage> with RouteAware {
   }
 
   Widget _buildBody() {
-    return FutureBuilder<List<Sheet>>(
-      future: _sheetsFuture,
+    return FutureBuilder<SyncResult>(
+      future: _syncFuture,
       builder: (context, snapshot) {
         if (snapshot.connectionState != ConnectionState.done) {
           return const Center(child: CircularProgressIndicator());
@@ -208,8 +229,9 @@ class _HomePageState extends State<HomePage> with RouteAware {
 
         if (snapshot.hasData) {
           return SheetsList(
-            sheets: snapshot.data!,
+            sheets: _sheets,
             onSheetSelected: _openSheet,
+            syncService: _syncService!,
           );
         }