some preference improvements

frontend/lib/structs/preferences.dart

@@ -0,0 +1,82 @@
+import 'package:flutter/material.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+
+class SinglePreference {
+  String name;
+  String description;
+  int value;
+  Icon icon;
+  String key;
+
+  SinglePreference({
+    required this.name,
+    required this.description,
+    required this.value,
+    required this.icon,
+    required this.key,
+  });
+}
+
+
+class UserPreferences {
+  List<SinglePreference> preferences = [
+    SinglePreference(
+      name: "Sightseeing",
+      description: "How much do you like sightseeing?",
+      value: 0,
+      icon: Icon(Icons.church),
+      key: "sightseeing",
+    ),
+    SinglePreference(
+      name: "Shopping",
+      description: "How much do you like shopping?",
+      value: 0,
+      icon: Icon(Icons.shopping_bag),
+      key: "shopping",
+    ),
+    SinglePreference(
+      name: "Foods & Drinks",
+      description: "How much do you like eating?",
+      value: 0,
+      icon: Icon(Icons.restaurant),
+      key: "eating",
+    ),
+    SinglePreference(
+      name: "Nightlife",
+      description: "How much do you like nightlife?",
+      value: 0,
+      icon: Icon(Icons.wine_bar),
+      key: "nightlife",
+    ),
+    SinglePreference(
+      name: "Nature",
+      description: "How much do you like nature?",
+      value: 0,
+      icon: Icon(Icons.landscape),
+      key: "nature",
+    ),
+    SinglePreference(
+      name: "Culture",
+      description: "How much do you like culture?",
+      value: 0,
+      icon: Icon(Icons.palette),
+      key: "culture",
+    ),
+  ];
+
+
+  void save() async {
+    SharedPreferences prefs = await SharedPreferences.getInstance();
+    for (SinglePreference pref in preferences) {
+      prefs.setInt(pref.key, pref.value);
+    }
+  }
+
+  void load() async {
+    SharedPreferences prefs = await SharedPreferences.getInstance();
+    for (SinglePreference pref in preferences) {
+      pref.value = prefs.getInt(pref.key) ?? 0;
+    }
+  }
+}