feat(inventory): add inventory preview functionality and related models

flutter/lib/core/api/api_paths.dart

@@ -11,6 +11,7 @@ class RecipeApiPaths {
   static String detail(int id) => '/recipes/$id';
   static String update(int id) => '/recipes/$id';
   static String remove(int id) => '/recipes/$id';
+  static String inventoryPreview(int id) => '/recipes/$id/inventory-preview';
   static const parseMarkdown = '/recipes/parse-markdown';
 }
 

flutter/lib/features/recipes/data/recipe_providers.dart

@@ -4,6 +4,7 @@ import '../../../core/api/api_providers.dart';
 import '../../../core/api/guarded_api_call.dart';
 import '../../../features/auth/data/auth_providers.dart';
 import '../domain/recipe.dart';
+import '../domain/inventory_preview.dart';
 import 'recipe_repository.dart';
 
 final recipeRepositoryProvider = Provider<RecipeRepository>((ref) {
@@ -26,3 +27,14 @@ final recipeDetailProvider =
     () => ref.read(recipeRepositoryProvider).fetchRecipeDetail(id, token: token),
   );
 });
+
+final inventoryPreviewProvider =
+    FutureProvider.family<InventoryPreview, int>((ref, id) async {
+  final token = await ref.watch(authStateProvider.future);
+  return guardedApiCall(
+    ref,
+    () => ref
+        .read(recipeRepositoryProvider)
+        .fetchInventoryPreview(id, token: token),
+  );
+});

flutter/lib/features/recipes/data/recipe_repository.dart

@@ -3,6 +3,7 @@ import '../../../core/api/api_exception.dart';
 import '../../../core/api/api_paths.dart';
 import '../domain/parsed_recipe.dart';
 import '../domain/recipe.dart';
+import '../domain/inventory_preview.dart';
 
 class RecipeRepository {
   final ApiClient _api;
@@ -93,6 +94,27 @@ class RecipeRepository {
     }
   }
 
+  Future<InventoryPreview> fetchInventoryPreview(int id,
+      {String? token}) async {
+    try {
+      final data = await _api.getJson(
+        RecipeApiPaths.inventoryPreview(id),
+        token: token,
+      );
+      if (data is! Map<String, dynamic>) {
+        throw const ApiException(
+            type: ApiErrorType.unknown, message: 'Ogiltigt svar från servern.');
+      }
+      return InventoryPreview.fromJson(data);
+    } on ApiException {
+      rethrow;
+    } catch (_) {
+      throw const ApiException(
+          type: ApiErrorType.network,
+          message: 'Kunde inte hämta inventariestatus.');
+    }
+  }
+
   Future<ParsedRecipe> parseMarkdown(String markdown,
       {String? token}) async {
     try {

flutter/lib/features/recipes/domain/inventory_preview.dart

@@ -0,0 +1,92 @@
+enum IngredientStatus { enough, missing, unitMismatch }
+
+class IngredientPreview {
+  final int ingredientId;
+  final int productId;
+  final String productName;
+  final double requiredQuantity;
+  final String requiredUnit;
+  final String? note;
+  final double availableQuantity;
+  final IngredientStatus status;
+  final double missingQuantity;
+
+  const IngredientPreview({
+    required this.ingredientId,
+    required this.productId,
+    required this.productName,
+    required this.requiredQuantity,
+    required this.requiredUnit,
+    this.note,
+    required this.availableQuantity,
+    required this.status,
+    required this.missingQuantity,
+  });
+
+  factory IngredientPreview.fromJson(Map<String, dynamic> json) {
+    final rawStatus = json['status'] as String? ?? 'missing';
+    final status = switch (rawStatus) {
+      'enough' => IngredientStatus.enough,
+      'unit_mismatch' => IngredientStatus.unitMismatch,
+      _ => IngredientStatus.missing,
+    };
+    return IngredientPreview(
+      ingredientId: json['ingredientId'] as int,
+      productId: json['productId'] as int,
+      productName: json['productName'] as String,
+      requiredQuantity: (json['requiredQuantity'] as num).toDouble(),
+      requiredUnit: json['requiredUnit'] as String? ?? '',
+      note: json['note'] as String?,
+      availableQuantity: (json['availableQuantity'] as num? ?? 0).toDouble(),
+      status: status,
+      missingQuantity: (json['missingQuantity'] as num? ?? 0).toDouble(),
+    );
+  }
+}
+
+class PreviewSummary {
+  final int totalIngredients;
+  final int enoughCount;
+  final int missingCount;
+  final int unitMismatchCount;
+  final bool canCookExactly;
+
+  const PreviewSummary({
+    required this.totalIngredients,
+    required this.enoughCount,
+    required this.missingCount,
+    required this.unitMismatchCount,
+    required this.canCookExactly,
+  });
+
+  factory PreviewSummary.fromJson(Map<String, dynamic> json) {
+    return PreviewSummary(
+      totalIngredients: json['totalIngredients'] as int,
+      enoughCount: json['enoughCount'] as int,
+      missingCount: json['missingCount'] as int,
+      unitMismatchCount: json['unitMismatchCount'] as int,
+      canCookExactly: json['canCookExactly'] as bool? ?? false,
+    );
+  }
+}
+
+class InventoryPreview {
+  final List<IngredientPreview> ingredients;
+  final PreviewSummary summary;
+
+  const InventoryPreview({
+    required this.ingredients,
+    required this.summary,
+  });
+
+  factory InventoryPreview.fromJson(Map<String, dynamic> json) {
+    final rawIngredients = json['ingredients'] as List<dynamic>? ?? [];
+    return InventoryPreview(
+      ingredients: rawIngredients
+          .map((e) => IngredientPreview.fromJson(e as Map<String, dynamic>))
+          .toList(),
+      summary: PreviewSummary.fromJson(
+          json['summary'] as Map<String, dynamic>? ?? {}),
+    );
+  }
+}

flutter/lib/features/recipes/presentation/recipe_detail_screen.dart

@@ -8,6 +8,7 @@ import '../../../core/ui/async_state_views.dart';
 import '../../auth/data/auth_providers.dart';
 import '../data/recipe_providers.dart';
 import '../domain/recipe.dart';
+import '../domain/inventory_preview.dart';
 
 class RecipeDetailScreen extends ConsumerWidget {
   final int recipeId;
@@ -182,9 +183,208 @@ class _RecipeBody extends StatelessWidget {
                 style: theme.textTheme.bodyMedium
                     ?.copyWith(height: 1.6)),
           ],
+          _InventoryPreviewSection(recipeId: recipe.id),
           const SizedBox(height: 40),
         ],
       ),
     );
   }
 }
+
+class _InventoryPreviewSection extends ConsumerStatefulWidget {
+  final int recipeId;
+
+  const _InventoryPreviewSection({required this.recipeId});
+
+  @override
+  ConsumerState<_InventoryPreviewSection> createState() =>
+      _InventoryPreviewSectionState();
+}
+
+class _InventoryPreviewSectionState
+    extends ConsumerState<_InventoryPreviewSection> {
+  bool _loaded = false;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        const SizedBox(height: 24),
+        Row(
+          children: [
+            Text('Vad saknas?', style: theme.textTheme.titleMedium),
+            const Spacer(),
+            if (!_loaded)
+              FilledButton.tonalIcon(
+                onPressed: () => setState(() => _loaded = true),
+                icon: const Icon(Icons.search, size: 16),
+                label: const Text('Kontrollera inventarie'),
+              ),
+            if (_loaded)
+              IconButton(
+                tooltip: 'Uppdatera',
+                icon: const Icon(Icons.refresh),
+                onPressed: () {
+                  ref.invalidate(inventoryPreviewProvider(widget.recipeId));
+                },
+              ),
+          ],
+        ),
+        if (_loaded) _InventoryPreviewResults(recipeId: widget.recipeId),
+      ],
+    );
+  }
+}
+
+class _InventoryPreviewResults extends ConsumerWidget {
+  final int recipeId;
+
+  const _InventoryPreviewResults({required this.recipeId});
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final previewAsync = ref.watch(inventoryPreviewProvider(recipeId));
+    final theme = Theme.of(context);
+
+    return previewAsync.when(
+      loading: () => const Padding(
+        padding: EdgeInsets.symmetric(vertical: 16),
+        child: Center(child: CircularProgressIndicator()),
+      ),
+      error: (error, _) => Padding(
+        padding: const EdgeInsets.only(top: 8),
+        child: Text(
+          mapErrorToUserMessage(error, context),
+          style: TextStyle(color: theme.colorScheme.error),
+        ),
+      ),
+      data: (preview) {
+        final summary = preview.summary;
+        return Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            const SizedBox(height: 8),
+            _SummaryChips(summary: summary),
+            const SizedBox(height: 12),
+            ...preview.ingredients.map(
+              (ing) => _IngredientPreviewRow(ingredient: ing),
+            ),
+          ],
+        );
+      },
+    );
+  }
+}
+
+class _SummaryChips extends StatelessWidget {
+  final PreviewSummary summary;
+
+  const _SummaryChips({required this.summary});
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final cs = theme.colorScheme;
+    return Wrap(
+      spacing: 8,
+      runSpacing: 4,
+      children: [
+        if (summary.canCookExactly)
+          Chip(
+            avatar: Icon(Icons.check_circle,
+                color: cs.onPrimary, size: 16),
+            label: const Text('Kan lagas!'),
+            backgroundColor: cs.primary,
+            labelStyle: TextStyle(color: cs.onPrimary),
+          )
+        else
+          Chip(
+            avatar: Icon(Icons.warning_amber,
+                color: cs.onErrorContainer, size: 16),
+            label: Text('Saknar ${summary.missingCount} ingrediens'
+                '${summary.missingCount == 1 ? '' : 'er'}'),
+            backgroundColor: cs.errorContainer,
+            labelStyle: TextStyle(color: cs.onErrorContainer),
+          ),
+        if (summary.unitMismatchCount > 0)
+          Chip(
+            avatar: Icon(Icons.swap_horiz,
+                color: cs.onTertiaryContainer, size: 16),
+            label: Text('${summary.unitMismatchCount} enhetsmismatch'),
+            backgroundColor: cs.tertiaryContainer,
+            labelStyle: TextStyle(color: cs.onTertiaryContainer),
+          ),
+      ],
+    );
+  }
+}
+
+class _IngredientPreviewRow extends StatelessWidget {
+  final IngredientPreview ingredient;
+
+  const _IngredientPreviewRow({required this.ingredient});
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final cs = theme.colorScheme;
+
+    final (icon, color) = switch (ingredient.status) {
+      IngredientStatus.enough => (Icons.check_circle_outline, cs.primary),
+      IngredientStatus.unitMismatch => (
+          Icons.swap_horiz,
+          cs.tertiary,
+        ),
+      IngredientStatus.missing => (Icons.cancel_outlined, cs.error),
+    };
+
+    String _fmt(double v) =>
+        v == v.truncateToDouble() ? v.toInt().toString() : v.toString();
+
+    final requiredStr =
+        '${_fmt(ingredient.requiredQuantity)} ${ingredient.requiredUnit}'.trim();
+    final availableStr =
+        '${_fmt(ingredient.availableQuantity)} ${ingredient.requiredUnit}'.trim();
+
+    final subtitle = switch (ingredient.status) {
+      IngredientStatus.enough => 'Tillgängligt: $availableStr',
+      IngredientStatus.missing => ingredient.availableQuantity > 0
+          ? 'Saknar ${_fmt(ingredient.missingQuantity)} ${ingredient.requiredUnit} '
+              '(har $availableStr)'
+          : 'Saknas helt',
+      IngredientStatus.unitMismatch =>
+        'Annan enhet i lager – kontrollera manuellt',
+    };
+
+    return Padding(
+      padding: const EdgeInsets.symmetric(vertical: 4),
+      child: Row(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Icon(icon, color: color, size: 18),
+          const SizedBox(width: 8),
+          Expanded(
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Text(
+                  '${ingredient.productName}'
+                  '${ingredient.note != null ? ' (${ingredient.note})' : ''}'
+                  ' – $requiredStr',
+                  style: theme.textTheme.bodyMedium,
+                ),
+                Text(
+                  subtitle,
+                  style: theme.textTheme.bodySmall
+                      ?.copyWith(color: color),
+                ),
+              ],
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}