feat: Add bulk delete and merge functionality for inventory items with DTOs and API endpoints

flutter/lib/features/inventory/presentation/inventory_screen.dart

@@ -5,13 +5,27 @@ import 'package:go_router/go_router.dart';
 import '../../../core/api/api_error_mapper.dart';
 import '../../../core/l10n/l10n.dart';
 import '../../../core/ui/async_state_views.dart';
+import '../../auth/data/auth_providers.dart';
 import '../data/inventory_providers.dart';
 import 'swipeable_inventory_tile.dart';
 
-class InventoryScreen extends ConsumerWidget {
+class InventoryScreen extends ConsumerStatefulWidget {
   const InventoryScreen({super.key});
 
+  @override
+  ConsumerState<InventoryScreen> createState() => _InventoryScreenState();
+}
+
+class _InventoryScreenState extends ConsumerState<InventoryScreen> {
+  final Set<int> _selectedIds = <int>{};
+
   static const _locationOptions = <String>['', 'Kyl', 'Frys', 'Skafferi'];
+
+  static const _weightOrVolumeUnits = <String>{
+    'g', 'gram', 'mg', 'milligram', 'hg', 'hektogram', 'kg', 'kilo', 'kilogram',
+    'ml', 'milliliter', 'cl', 'centiliter', 'dl', 'deciliter', 'l', 'liter',
+  };
+
   List<({String value, String label})> _sortOptions(BuildContext context) => [
     (value: '', label: context.l10n.inventorySortLatest),
     (value: 'nameAsc', label: context.l10n.inventorySortNameAsc),
@@ -20,6 +34,232 @@ class InventoryScreen extends ConsumerWidget {
     (value: 'l1CategoryAsc', label: 'L1-kategori (A-O)'),
   ];
 
+  void _startSelection(int id) {
+    setState(() {
+      _selectedIds.add(id);
+    });
+  }
+
+  void _toggleSelection(int id) {
+    setState(() {
+      if (_selectedIds.contains(id)) {
+        _selectedIds.remove(id);
+      } else {
+        _selectedIds.add(id);
+      }
+    });
+  }
+
+  void _clearSelection() {
+    setState(() {
+      _selectedIds.clear();
+    });
+  }
+
+  void _selectAllVisible(List<dynamic> visibleItems) {
+    setState(() {
+      _selectedIds
+        ..clear()
+        ..addAll(visibleItems.map<int>((item) => item.id as int));
+    });
+  }
+
+  bool _isWeightOrVolumeUnit(String unit) {
+    return _weightOrVolumeUnits.contains(unit.trim().toLowerCase());
+  }
+
+  String _preferredUnit(List<String> units) {
+    for (final unit in units) {
+      if (_isWeightOrVolumeUnit(unit)) return unit;
+    }
+    return units.first;
+  }
+
+  Future<String?> _askMergeTargetUnit(BuildContext context, List<String> units) async {
+    if (units.isEmpty) return null;
+    if (units.length == 1) return units.first;
+
+    var selected = _preferredUnit(units);
+
+    return showDialog<String>(
+      context: context,
+      builder: (dialogContext) => StatefulBuilder(
+        builder: (dialogContext, setDialogState) => AlertDialog(
+          title: const Text('Välj enhet för merge'),
+          content: Column(
+            mainAxisSize: MainAxisSize.min,
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              const Text(
+                'Poster har olika enhet. Välj vilken enhet den sammanslagna posten ska använda.',
+              ),
+              const SizedBox(height: 12),
+              DropdownButtonFormField<String>(
+                initialValue: selected,
+                decoration: const InputDecoration(
+                  labelText: 'Enhet',
+                  border: OutlineInputBorder(),
+                ),
+                items: units
+                    .map(
+                      (unit) => DropdownMenuItem<String>(
+                        value: unit,
+                        child: Text(unit),
+                      ),
+                    )
+                    .toList(),
+                onChanged: (value) {
+                  if (value == null) return;
+                  setDialogState(() => selected = value);
+                },
+              ),
+            ],
+          ),
+          actions: [
+            TextButton(
+              onPressed: () => Navigator.pop(dialogContext),
+              child: Text(context.l10n.cancelAction),
+            ),
+            FilledButton(
+              onPressed: () => Navigator.pop(dialogContext, selected),
+              child: const Text('Merge'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Future<void> _mergeSelected(BuildContext context, List<dynamic> allItems) async {
+    final selectedItems = allItems
+        .where((item) => _selectedIds.contains(item.id))
+        .toList();
+
+    if (selectedItems.length < 2) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('Välj minst två poster för merge.')),
+      );
+      return;
+    }
+
+    final productIds = selectedItems.map((item) => item.productId).toSet();
+    if (productIds.length > 1) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('Valda poster måste ha samma produkt för merge.')),
+      );
+      return;
+    }
+
+    final units = <String>[];
+    final seenUnits = <String>{};
+    for (final item in selectedItems) {
+      final unit = (item.unit as String).trim();
+      final key = unit.toLowerCase();
+      if (seenUnits.add(key)) {
+        units.add(unit);
+      }
+    }
+
+    final targetUnit = await _askMergeTargetUnit(context, units);
+    if (!context.mounted || targetUnit == null) return;
+
+    try {
+      final token = await ref.read(authStateProvider.future);
+      final ids = selectedItems.map<int>((item) => item.id as int).toList();
+      await ref.read(inventoryRepositoryProvider).mergeInventoryItems(
+            ids,
+            targetUnit: units.length > 1 ? targetUnit : null,
+            token: token,
+          );
+      ref.invalidate(inventoryProvider);
+      if (!mounted) return;
+      setState(() => _selectedIds.clear());
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('Poster sammanslagna.')),
+      );
+    } catch (e) {
+      if (!mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        buildCopyableErrorSnackBar(context, mapErrorToUserMessage(e, context)),
+      );
+    }
+  }
+
+  Future<void> _deleteSelected(BuildContext context, List<dynamic> allItems) async {
+    final ids = allItems
+        .where((item) => _selectedIds.contains(item.id))
+        .map<int>((item) => item.id as int)
+        .toList();
+    if (ids.isEmpty) return;
+
+    final confirmed = await showDialog<bool>(
+      context: context,
+      builder: (dialogContext) => AlertDialog(
+        title: const Text('Ta bort markerade poster'),
+        content: Text('Vill du verkligen ta bort ${ids.length} markerade poster?'),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(dialogContext, false),
+            child: Text(context.l10n.cancelAction),
+          ),
+          FilledButton(
+            onPressed: () => Navigator.pop(dialogContext, true),
+            child: Text(context.l10n.deleteAction),
+          ),
+        ],
+      ),
+    );
+
+    if (confirmed != true || !context.mounted) return;
+
+    try {
+      final token = await ref.read(authStateProvider.future);
+      await ref.read(inventoryRepositoryProvider).bulkDeleteInventoryItems(ids, token: token);
+      ref.invalidate(inventoryProvider);
+      if (!mounted) return;
+      setState(() => _selectedIds.clear());
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(content: Text('${ids.length} poster borttagna.')),
+      );
+    } catch (e) {
+      if (!mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        buildCopyableErrorSnackBar(context, mapErrorToUserMessage(e, context)),
+      );
+    }
+  }
+
+  Future<void> _openBulkActions(BuildContext context, List<dynamic> allItems) async {
+    if (_selectedIds.isEmpty) return;
+    final action = await showDialog<String>(
+      context: context,
+      builder: (dialogContext) => AlertDialog(
+        title: const Text('Hantera markerade poster'),
+        content: Text('Du har markerat ${_selectedIds.length} poster. Välj åtgärd.'),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(dialogContext),
+            child: Text(context.l10n.cancelAction),
+          ),
+          OutlinedButton(
+            onPressed: () => Navigator.pop(dialogContext, 'delete'),
+            child: Text(context.l10n.deleteAction),
+          ),
+          FilledButton(
+            onPressed: () => Navigator.pop(dialogContext, 'merge'),
+            child: const Text('Merge'),
+          ),
+        ],
+      ),
+    );
+
+    if (action == 'merge') {
+      await _mergeSelected(context, allItems);
+    } else if (action == 'delete') {
+      await _deleteSelected(context, allItems);
+    }
+  }
+
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final location = ref.watch(inventoryLocationFilterProvider);
@@ -33,6 +273,17 @@ class InventoryScreen extends ConsumerWidget {
         onRetry: () => ref.invalidate(inventoryProvider),
       ),
       data: (items) {
+        final itemIds = items.map((item) => item.id).toSet();
+        final staleIds = _selectedIds.where((id) => !itemIds.contains(id)).toList();
+        if (staleIds.isNotEmpty) {
+          WidgetsBinding.instance.addPostFrameCallback((_) {
+            if (!mounted) return;
+            setState(() {
+              _selectedIds.removeWhere((id) => !itemIds.contains(id));
+            });
+          });
+        }
+
         final visibleItems = [...items];
         if (sort == 'l1CategoryAsc') {
           visibleItems.sort((a, b) {
@@ -125,6 +376,48 @@ class InventoryScreen extends ConsumerWidget {
           ),
         );
 
+        final selectedSection = _selectedIds.isEmpty
+            ? const SizedBox.shrink()
+            : Padding(
+                padding: const EdgeInsets.fromLTRB(12, 4, 12, 4),
+                child: Card(
+                  child: Padding(
+                    padding: const EdgeInsets.all(12),
+                    child: Column(
+                      crossAxisAlignment: CrossAxisAlignment.start,
+                      children: [
+                        Text(
+                          '${_selectedIds.length} markerade poster',
+                          style: Theme.of(context).textTheme.titleSmall,
+                        ),
+                        const SizedBox(height: 8),
+                        Wrap(
+                          spacing: 8,
+                          runSpacing: 8,
+                          children: [
+                            FilledButton.icon(
+                              onPressed: () => _openBulkActions(context, items),
+                              icon: const Icon(Icons.playlist_add_check),
+                              label: const Text('Hantera markerade'),
+                            ),
+                            OutlinedButton.icon(
+                              onPressed: () => _selectAllVisible(visibleItems),
+                              icon: const Icon(Icons.select_all),
+                              label: const Text('Markera alla synliga'),
+                            ),
+                            OutlinedButton.icon(
+                              onPressed: _clearSelection,
+                              icon: const Icon(Icons.deselect),
+                              label: const Text('Avmarkera'),
+                            ),
+                          ],
+                        ),
+                      ],
+                    ),
+                  ),
+                ),
+              );
+
         if (visibleItems.isEmpty) {
           return Stack(
             children: [
@@ -133,6 +426,7 @@ class InventoryScreen extends ConsumerWidget {
                 padding: const EdgeInsets.only(bottom: 88),
                 children: [
                   headerSection,
+                  selectedSection,
                   filterSection,
                   EmptyStateView(title: context.l10n.inventoryEmpty),
                 ],
@@ -155,13 +449,26 @@ class InventoryScreen extends ConsumerWidget {
             ListView.separated(
               key: const PageStorageKey<String>('inventory-main-list'),
               padding: const EdgeInsets.only(bottom: 88),
-              itemCount: visibleItems.length + 2,
+              itemCount: visibleItems.length + (_selectedIds.isEmpty ? 2 : 3),
               separatorBuilder: (_, __) => const Divider(height: 1),
               itemBuilder: (context, index) {
                 if (index == 0) return filterSection;
                 if (index == 1) return headerSection;
-                final item = visibleItems[index - 2];
-                return SwipeableInventoryTile(item: item);
+                if (_selectedIds.isNotEmpty && index == 2) return selectedSection;
+                final item = visibleItems[index - (_selectedIds.isEmpty ? 2 : 3)];
+                return SwipeableInventoryTile(
+                  item: item,
+                  selectableMode: _selectedIds.isNotEmpty,
+                  selected: _selectedIds.contains(item.id),
+                  onToggleSelected: () => _toggleSelection(item.id),
+                  onLongPress: () {
+                    if (_selectedIds.isEmpty) {
+                      _startSelection(item.id);
+                    } else {
+                      _toggleSelection(item.id);
+                    }
+                  },
+                );
               },
             ),
             Positioned(