add alot

lib/viewmodels/bar_screen_view_model.dart

@@ -8,9 +8,11 @@ import '../services/product_service.dart';
 
 class BarScreenViewModel extends ChangeNotifier {
   final BarTabService barTabService;
+  final ProductService productService;
 
   BarScreenViewModel({
     required this.barTabService,
+    required this.productService,
   });
 
   List<BarTab> _tabs = [];
@@ -74,9 +76,7 @@ class BarScreenViewModel extends ChangeNotifier {
   }
 
   Future<void> createTab(String customerName) async {
-    final tab = await barTabService.createTab(
-      customerName: customerName,
-    );
+    final tab = await barTabService.createTab(customerName: customerName);
 
     _selectedTabId = tab.id;
     await _reloadTabs();
@@ -87,23 +87,34 @@ class BarScreenViewModel extends ChangeNotifier {
 
     if (tab == null) return;
 
+    if (product.stockQuantity <= 0) {
+      throw Exception('Product is out of stock.');
+    }
+
     await barTabService.addProductToTab(
       tabId: tab.id,
       product: product,
     );
 
+    await productService.decreaseStock(product.id, 1);
+
     await _reloadTabs();
   }
 
-  Future<void> changeItemQuantity(
-      TabItem item,
-      int quantity,
-      ) async {
+  Future<void> changeItemQuantity(TabItem item, int quantity) async {
+    final difference = quantity - item.quantity;
+
     await barTabService.updateTabItemQuantity(
       tabItemId: item.id,
       quantity: quantity,
     );
 
+    if (difference > 0) {
+      await productService.decreaseStock(item.productId, difference);
+    } else if (difference < 0) {
+      await productService.increaseStock(item.productId, -difference);
+    }
+
     await _reloadTabs();
   }
 
@@ -126,10 +137,11 @@ class BarScreenViewModel extends ChangeNotifier {
   Future<void> _reloadTabs() async {
     _tabs = await barTabService.getOpenTabs();
 
-    if (_selectedTabId == null || !_tabs.any((tab) => tab.id == _selectedTabId)) {
+    if (_selectedTabId == null ||
+        !_tabs.any((tab) => tab.id == _selectedTabId)) {
       _selectedTabId = _tabs.isEmpty ? null : _tabs.first.id;
     }
 
     notifyListeners();
   }
-}
+}

lib/viewmodels/product_list_view_model.dart

@@ -56,6 +56,20 @@ class ProductListViewModel extends ChangeNotifier {
       _isLoading = false;
       notifyListeners();
     }
+
+    try {
+      _products = await productService.getProducts();
+
+      debugPrint(
+        _products.map((p) => '${p.name}: ${p.stockQuantity}').join('\n'),
+      );
+    } catch (_) {
+      _errorMessage = 'Could not load products.';
+    } finally {
+      _hasLoaded = true;
+      _isLoading = false;
+      notifyListeners();
+    }
   }
 
   Future<void> addProduct({

lib/viewmodels/settings_view_model.dart

@@ -0,0 +1,66 @@
+import 'package:flutter/foundation.dart';
+
+import '../models/settings.dart';
+import '../services/settings_service.dart';
+
+class SettingsViewModel extends ChangeNotifier {
+  final SettingsService settingsService;
+
+  SettingsViewModel({required this.settingsService});
+
+  AppSettings _settings = AppSettings.defaults;
+  bool _isLoading = false;
+  bool _hasLoaded = false;
+  String? _errorMessage;
+
+  AppSettings get settings => _settings;
+  bool get isLoading => _isLoading;
+  bool get hasLoaded => _hasLoaded;
+  String? get errorMessage => _errorMessage;
+
+  Future<void> ensureLoaded() async {
+    if (_hasLoaded || _isLoading) return;
+    await load();
+  }
+
+  Future<void> load() async {
+    if (_isLoading) return;
+
+    _isLoading = true;
+    _errorMessage = null;
+    notifyListeners();
+
+    try {
+      _settings = await settingsService.getSettings();
+    } catch (_) {
+      _errorMessage = 'Could not load settings.';
+    } finally {
+      _hasLoaded = true;
+      _isLoading = false;
+      notifyListeners();
+    }
+  }
+
+  /// Just flips the preference flag. Caller is responsible for having
+  /// already set/verified the actual PIN via PinLockViewModel first.
+  Future<void> updatePinRequired(bool value) =>
+      _save(_settings.copyWith(pinRequired: value));
+
+  Future<void> updateThemeMode(AppThemeMode mode) =>
+      _save(_settings.copyWith(themeMode: mode));
+
+  Future<void> _save(AppSettings updated) async {
+    final previous = _settings;
+    _settings = updated;
+    _errorMessage = null;
+    notifyListeners();
+
+    try {
+      await settingsService.saveSettings(updated);
+    } catch (_) {
+      _settings = previous;
+      _errorMessage = 'Could not save settings.';
+      notifyListeners();
+    }
+  }
+}