various ingredient form UX issues

* upon scan completion, give more useful preview of the found ingredient
* use ID field to track whether the form is "loaded" with a valid
  ingredient or not
* don't trigger search if an ingredient is loaded, unless user changes
  the pattern
* always show meal item preview, whether loaded from recent items, or
  from scan result

lib/widgets/nutrition/forms.dart

@@ -169,7 +169,6 @@ class IngredientFormState extends State<IngredientForm> {
   final _timeController = TextEditingController(); // optional
   final _mealItem = MealItem.empty();
 
-  bool validIngredientId = false;
   @override
   void initState() {
     super.initState();
@@ -287,7 +286,7 @@ class IngredientFormState extends State<IngredientForm> {
                   ),
               ],
             ),
-            if (validIngredientId)
+            if (ingredientIdController.text.isNotEmpty)
               Padding(
                 padding: const EdgeInsets.all(8.0),
                 child: Column(
@@ -302,10 +301,9 @@ class IngredientFormState extends State<IngredientForm> {
                       builder: (BuildContext context, AsyncSnapshot<Ingredient> snapshot) {
                         if (snapshot.hasData) {
                           _mealItem.ingredient = snapshot.data!;
-                          return ListTile(
-                            leading: IngredientAvatar(ingredient: _mealItem.ingredient),
-                            title:
-                                Text(getShortNutritionValues(_mealItem.nutritionalValues, context)),
+                          return MealItemTile(
+                            ingredient: _mealItem.ingredient,
+                            nutritionalValues: _mealItem.nutritionalValues,
                           );
                         } else if (snapshot.hasError) {
                           return Padding(
@@ -365,14 +363,13 @@ class IngredientFormState extends State<IngredientForm> {
                   return Card(
                     child: ListTile(
                       onTap: () {
-                        _ingredientController.text = widget.recent[index].ingredient.name;
-                        _ingredientIdController.text =
-                            widget.recent[index].ingredient.id.toString();
-                        _amountController.text = widget.recent[index].amount.toStringAsFixed(0);
                         setState(() {
+                          _ingredientController.text = widget.recent[index].ingredient.name;
+                          _ingredientIdController.text =
+                              widget.recent[index].ingredient.id.toString();
+                          _amountController.text = widget.recent[index].amount.toStringAsFixed(0);
                           _mealItem.ingredientId = widget.recent[index].ingredientId;
                           _mealItem.amount = widget.recent[index].amount;
-                          validIngredientId = true;
                         });
                       },
                       title: Text(

lib/widgets/nutrition/widgets.dart

@@ -32,6 +32,7 @@ import 'package:wger/models/exercises/ingredient_api.dart';
 import 'package:wger/models/nutrition/ingredient.dart';
 import 'package:wger/models/nutrition/log.dart';
 import 'package:wger/models/nutrition/nutritional_plan.dart';
+import 'package:wger/models/nutrition/nutritional_values.dart';
 import 'package:wger/providers/nutrition.dart';
 import 'package:wger/widgets/core/core.dart';
 import 'package:wger/widgets/nutrition/helpers.dart';
@@ -118,6 +119,11 @@ class _IngredientTypeaheadState extends State<IngredientTypeahead> {
                 }
                 return null;
               },
+              onChanged: (value) {
+                // if user changes the pattern, it means they want to drop the
+                // currently loaded ingredient (if any) and start a new search
+                widget._ingredientIdController.text = '';
+              },
               decoration: InputDecoration(
                 prefixIcon: const Icon(Icons.search),
                 labelText: AppLocalizations.of(context).searchIngredient,
@@ -126,7 +132,8 @@ class _IngredientTypeaheadState extends State<IngredientTypeahead> {
             );
           },
           suggestionsCallback: (pattern) {
-            if (pattern == '') {
+            // don't do search if user has already loaded a specific item
+            if (pattern == '' || widget._ingredientIdController.text.isNotEmpty) {
               return null;
             }
 
@@ -188,6 +195,7 @@ class _IngredientTypeaheadState extends State<IngredientTypeahead> {
             }
             final result = await Provider.of<NutritionPlansProvider>(context, listen: false)
                 .searchIngredientWithCode(barcode);
+            // TODO: show spinner...
             if (!mounted) {
               return;
             }
@@ -198,7 +206,16 @@ class _IngredientTypeaheadState extends State<IngredientTypeahead> {
                 builder: (ctx) => AlertDialog(
                   key: const Key('found-dialog'),
                   title: Text(AppLocalizations.of(context).productFound),
-                  content: Text(AppLocalizations.of(context).productFoundDescription(result.name)),
+                  content: Column(
+                    mainAxisSize: MainAxisSize.min,
+                    children: [
+                      Text(AppLocalizations.of(context).productFoundDescription(result.name)),
+                      MealItemTile(
+                        ingredient: result,
+                        nutritionalValues: result.nutritionalValues,
+                      ),
+                    ],
+                  ),
                   actions: [
                     TextButton(
                       key: const Key('found-dialog-confirm-button'),
@@ -357,3 +374,23 @@ class IngredientAvatar extends StatelessWidget {
         : const CircleIconAvatar(Icon(Icons.image, color: Colors.grey));
   }
 }
+
+class MealItemTile extends StatelessWidget {
+  final Ingredient ingredient;
+  final NutritionalValues nutritionalValues;
+
+  const MealItemTile({
+    super.key,
+    required this.ingredient,
+    required this.nutritionalValues,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return ListTile(
+      leading: IngredientAvatar(ingredient: ingredient),
+      title: Text(getShortNutritionValues(nutritionalValues, context)),
+      subtitle: Text(ingredient.id.toString()),
+    );
+  }
+}