feat: 4223 - comparison page for 3 random products on dev mode

New file:
* `compare_products3_page.dart`: Test page about comparing 3 products. Work in progress.

Impacted files:
* `attributes_card_helper.dart`: refactored introducing two new reusable methods
* `nutrition_container.dart`: refactored introducing one reusable getter
* `product_cards_helper.dart`: refactored introducing one new reusable method
* `user_preferences_dev_mode.dart`: added an item computing 3 random products and showing the product comparison page

packages/smooth_app/lib/helpers/attributes_card_helper.dart

@@ -32,17 +32,35 @@ enum AttributeEvaluation {
   }
 }
 
-Widget getAttributeDisplayIcon(final Attribute attribute) => Padding(
-      padding: const EdgeInsetsDirectional.only(end: VERY_SMALL_SPACE),
-      child: _attributeMatchComparison(
-        attribute,
-        const Icon(CupertinoIcons.question, color: RED_COLOR),
-        const Icon(Icons.lens, color: RED_COLOR),
-        const Icon(Icons.lens, color: LIGHT_ORANGE_COLOR),
-        const Icon(Icons.lens, color: LIGHT_ORANGE_COLOR),
-        const Icon(Icons.lens, color: LIGHT_GREEN_COLOR),
-        const Icon(Icons.lens, color: LIGHT_GREEN_COLOR),
-      ),
+Widget getAttributeDisplayIcon(final Attribute attribute) {
+  final Color color = getAttributeDisplayBackgroundColor(attribute);
+  final IconData iconData = getAttributeDisplayIconData(attribute);
+  return Padding(
+    padding: const EdgeInsetsDirectional.only(end: VERY_SMALL_SPACE),
+    child: Icon(iconData, color: color),
+  );
+}
+
+Color getAttributeDisplayBackgroundColor(final Attribute attribute) =>
+    _attributeMatchComparison<Color>(
+      attribute,
+      RED_COLOR,
+      RED_COLOR,
+      LIGHT_ORANGE_COLOR,
+      LIGHT_ORANGE_COLOR,
+      LIGHT_GREEN_COLOR,
+      LIGHT_GREEN_COLOR,
+    );
+
+IconData getAttributeDisplayIconData(final Attribute attribute) =>
+    _attributeMatchComparison<IconData>(
+      attribute,
+      CupertinoIcons.question,
+      Icons.lens,
+      Icons.lens,
+      Icons.lens,
+      Icons.lens,
+      Icons.lens,
     );
 
 bool isMatchAvailable(Attribute attribute) {

packages/smooth_app/lib/helpers/product_cards_helper.dart

@@ -95,7 +95,24 @@ List<Attribute> getMandatoryAttributes(
   final List<String> attributeGroupOrder,
   final Set<String> attributesToExcludeIfStatusIsUnknown,
   final ProductPreferences preferences,
-) {
+) =>
+    getSortedAttributes(
+      product,
+      attributeGroupOrder,
+      attributesToExcludeIfStatusIsUnknown,
+      preferences,
+      PreferenceImportance.ID_MANDATORY,
+    );
+
+/// Returns the attributes, ordered by importance desc and attribute group order
+List<Attribute> getSortedAttributes(
+  final Product product,
+  final List<String> attributeGroupOrder,
+  final Set<String> attributesToExcludeIfStatusIsUnknown,
+  final ProductPreferences preferences,
+  final String importance, {
+  final bool excludeMainScoreAttributes = true,
+}) {
   final List<Attribute> result = <Attribute>[];
   if (product.attributeGroups == null) {
     return result;
@@ -106,9 +123,10 @@ List<Attribute> getMandatoryAttributes(
   for (final AttributeGroup attributeGroup in product.attributeGroups!) {
     mandatoryAttributesByGroup[attributeGroup.id!] = getFilteredAttributes(
       attributeGroup,
-      PreferenceImportance.ID_MANDATORY,
+      importance,
       attributesToExcludeIfStatusIsUnknown,
       preferences,
+      excludeMainScoreAttributes: excludeMainScoreAttributes,
     );
   }
 
@@ -131,15 +149,17 @@ List<Attribute> getFilteredAttributes(
   final AttributeGroup attributeGroup,
   final String importance,
   final Set<String> attributesToExcludeIfStatusIsUnknown,
-  final ProductPreferences preferences,
-) {
+  final ProductPreferences preferences, {
+  final bool excludeMainScoreAttributes = true,
+}) {
   final List<Attribute> result = <Attribute>[];
   if (attributeGroup.attributes == null) {
     return result;
   }
   for (final Attribute attribute in attributeGroup.attributes!) {
     final String attributeId = attribute.id!;
-    if (SCORE_ATTRIBUTE_IDS.contains(attributeId)) {
+    if (excludeMainScoreAttributes &&
+        SCORE_ATTRIBUTE_IDS.contains(attributeId)) {
       continue;
     }
     if (attributeGroup.id == AttributeGroup.ATTRIBUTE_GROUP_LABELS) {

packages/smooth_app/lib/pages/preferences/user_preferences_dev_mode.dart

@@ -1,3 +1,5 @@
+import 'dart:math';
+
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_gen/gen_l10n/app_localizations.dart';
@@ -8,6 +10,7 @@ import 'package:smooth_app/background/background_task_badge.dart';
 import 'package:smooth_app/data_models/continuous_scan_model.dart';
 import 'package:smooth_app/data_models/product_list.dart';
 import 'package:smooth_app/data_models/user_preferences.dart';
+import 'package:smooth_app/database/dao_product.dart';
 import 'package:smooth_app/database/dao_product_list.dart';
 import 'package:smooth_app/database/local_database.dart';
 import 'package:smooth_app/generic_lib/dialogs/smooth_alert_dialog.dart';
@@ -18,6 +21,8 @@ import 'package:smooth_app/pages/offline_tasks_page.dart';
 import 'package:smooth_app/pages/preferences/abstract_user_preferences.dart';
 import 'package:smooth_app/pages/preferences/user_preferences_dev_debug_info.dart';
 import 'package:smooth_app/pages/preferences/user_preferences_page.dart';
+import 'package:smooth_app/pages/product/compare_products3_page.dart';
+import 'package:smooth_app/pages/product/ordered_nutrients_cache.dart';
 import 'package:smooth_app/query/product_query.dart';
 
 /// Full page display of "dev mode" for the preferences page.
@@ -338,6 +343,67 @@ class UserPreferencesDevMode extends AbstractUserPreferences {
             ProductQuery.setLanguage(context, userPreferences);
           },
         ),
+        ListTile(
+          title: const Text('Side by side comparison: 3 random products'),
+          onTap: () async {
+            final LocalDatabase localDatabase = context.read<LocalDatabase>();
+            final DaoProduct daoProduct = DaoProduct(localDatabase);
+            final List<String> allBarcodes = await daoProduct.getAllKeys();
+            final int length = allBarcodes.length;
+            if (length < 3) {
+              if (context.mounted) {
+                ScaffoldMessenger.of(context).showSnackBar(
+                  const SnackBar(
+                    content: Text(
+                      'We need at least 3 products in the local database!',
+                    ),
+                  ),
+                );
+              }
+              return;
+            }
+            final Random random = Random();
+            final int index1 = random.nextInt(length);
+            final int index2 = (index1 + 1) % length;
+            final int index3 = (index1 + 2) % length;
+            final Product product1 =
+                (await daoProduct.get(allBarcodes[index1]))!;
+            final Product product2 =
+                (await daoProduct.get(allBarcodes[index2]))!;
+            final Product product3 =
+                (await daoProduct.get(allBarcodes[index3]))!;
+            if (context.mounted) {
+              final OrderedNutrientsCache? cache =
+                  await OrderedNutrientsCache.getCache(context);
+              if (context.mounted) {
+                if (cache == null) {
+                  ScaffoldMessenger.of(context).showSnackBar(
+                    SnackBar(
+                      content: Text(
+                        AppLocalizations.of(context)
+                            .nutrition_cache_loading_error,
+                      ),
+                    ),
+                  );
+                  return;
+                }
+                await Navigator.push<void>(
+                  context,
+                  MaterialPageRoute<void>(
+                    builder: (BuildContext context) => CompareProducts3Page(
+                      products: <Product>[
+                        product1,
+                        product2,
+                        product3,
+                      ],
+                      orderedNutrientsCache: cache,
+                    ),
+                  ),
+                );
+              }
+            }
+          },
+        ),
         ListTile(
           title: const Text('Debugging information'),
           onTap: () async => Navigator.of(context).push(MaterialPageRoute<void>(