quite a few UX improvements

frontend/lib/utils/get_first_page.dart

@@ -1,44 +1,50 @@
 import 'package:anyway/main.dart';
+import 'package:anyway/pages/no_trips_page.dart';
+import 'package:anyway/structs/agreement.dart';
 import 'package:flutter/material.dart';
 
 import 'package:anyway/structs/trip.dart';
-import 'package:anyway/utils/load_trips.dart';
 import 'package:anyway/pages/current_trip.dart';
 import 'package:anyway/pages/onboarding.dart';
 
 
 Widget getFirstPage() {
-  SavedTrips trips = savedTrips;
-  trips.loadTrips();
-
-  return ListenableBuilder(
-    listenable: trips,
-    builder: (BuildContext context, Widget? child) {
-      List<Trip> items = trips.trips;
-      if (items.isNotEmpty) {
-        return TripPage(trip: items[0]);
+  // check if the user has already seen the onboarding and agreed to the terms of service
+  return FutureBuilder(
+    future: getAgreement(),
+    builder: (context, snapshot) {
+      if (snapshot.connectionState == ConnectionState.done) {
+        if (snapshot.hasData) {
+          Agreement agrement = snapshot.data!;
+          if (agrement.agreed) {
+            return FutureBuilder(
+              future: savedTrips.loadTrips(),
+              builder: (context, snapshot) {
+                if (snapshot.connectionState == ConnectionState.done) {
+                  if (snapshot.hasData) {
+                    List<Trip> trips = snapshot.data!;
+                    if (trips.length > 0) {
+                      return TripPage(trip: trips[0]);
+                    } else {
+                      return NoTripsPage();
+                    }
+                  } else {
+                    return Center(child: CircularProgressIndicator());
+                  }
+                } else {
+                  return Center(child: CircularProgressIndicator());
+                }
+              },
+            );
+          } else {
+            return OnboardingPage();
+          }
+        } else {
+          return OnboardingPage();
+        }
       } else {
-        return const OnboardingPage();
+        return OnboardingPage();
       }
-    }
+    },
   );
-  // Future<List<Trip>> trips = loadTrips();
-  // // test if there are any active trips
-  // // if there are, return the trip list
-  // // if there are not, return the onboarding page
-  // return FutureBuilder(
-  //   future: trips,
-  //   builder: (context, snapshot) {
-  //     if (snapshot.hasData) {
-  //       List<Trip> availableTrips = snapshot.data!;
-  //       if (availableTrips.isNotEmpty) {
-  //         return TripPage(trip: availableTrips[0]);
-  //       } else {
-  //         return OnboardingPage();
-  //       }
-  //     } else {
-  //       return CircularProgressIndicator();
-  //     }
-  //   }
-  // );
 }

frontend/lib/utils/load_trips.dart

@@ -8,7 +8,7 @@ class SavedTrips extends ChangeNotifier {
 
   List<Trip> get trips => _trips;
 
-  void loadTrips() async {
+  Future<List<Trip>> loadTrips() async {
     SharedPreferences prefs = await SharedPreferences.getInstance();
 
     List<Trip> trips = [];
@@ -21,6 +21,7 @@ class SavedTrips extends ChangeNotifier {
     }
     _trips = trips;
     notifyListeners();
+    return trips;
   }
 
   void addTrip(Trip trip) async {