Polish the last exercise submission step

Show a spinner while the requests are being processed (still no error handling
here though) and show a pop up on success that allows the user to go to the
exercise's detail page

Closes #341

lib/l10n/app_en.arb

@@ -93,6 +93,10 @@
   "@labelDashboard": {
     "description": "Title for screen dashboard"
   },
+  "success": "Success",
+  "@success": {
+    "description": "Message when an action completed successfully, usually used as a heading"
+  },
   "successfullyDeleted": "Deleted",
   "@successfullyDeleted": {
     "description": "Message when an item was successfully deleted"
@@ -629,6 +633,7 @@
       }
     }
   },
+  "cacheWarning": "Due to caching it might take some time till the changes are visible throughout the application.",
   "abs": "Abs",
   "arms": "Arms",
   "back": "Back",

lib/providers/add_exercise.dart

@@ -204,12 +204,12 @@ class AddExerciseProvider with ChangeNotifier {
       await addExerciseTranslation(exerciseTranslationLang);
     }
 
-    // Clear everything
-    //clear();
-
     // Create the images
     await addImages(base);
 
+    // Clear everything
+    clear();
+
     // Return exercise ID
     return base.id!;
   }

lib/screens/add_exercise_screen.dart

@@ -41,6 +41,8 @@ class AddExerciseStepper extends StatefulWidget {
 class _AddExerciseStepperState extends State<AddExerciseStepper> {
   int _currentStep = 0;
   int lastStepIndex = AddExerciseStepper.STEPS_IN_FORM - 1;
+  bool _isLoading = false;
+
   final List<GlobalKey<FormState>> _keys = [
     GlobalKey<FormState>(),
     GlobalKey<FormState>(),
@@ -57,17 +59,58 @@ class _AddExerciseStepperState extends State<AddExerciseStepper> {
           mainAxisAlignment: MainAxisAlignment.spaceAround,
           children: [
             OutlinedButton(
-                onPressed: details.onStepCancel,
-                child: Text(AppLocalizations.of(context).previous)),
+              onPressed: details.onStepCancel,
+              child: Text(AppLocalizations.of(context).previous),
+            ),
             if (_currentStep == lastStepIndex)
               ElevatedButton(
-                onPressed: () async {
-                  final id = await context.read<AddExerciseProvider>().addExercise();
-                  final base = await context.read<ExercisesProvider>().fetchAndSetExerciseBase(id);
+                onPressed: _isLoading
+                    ? null
+                    : () async {
+                        setState(() {
+                          _isLoading = true;
+                        });
+                        final addExerciseProvider = context.read<AddExerciseProvider>();
+                        final exerciseProvider = context.read<ExercisesProvider>();
 
-                  Navigator.pushNamed(context, ExerciseDetailScreen.routeName, arguments: base);
-                },
-                child: Text(AppLocalizations.of(context).save),
+                        final baseId = await addExerciseProvider.addExercise();
+                        final base = await exerciseProvider.fetchAndSetExerciseBase(baseId);
+                        final name =
+                            base.getExercise(Localizations.localeOf(context).languageCode).name;
+
+                        setState(() {
+                          _isLoading = false;
+                        });
+
+                        if (!context.mounted) return;
+                        return showDialog(
+                          context: context,
+                          builder: (BuildContext context) {
+                            return AlertDialog(
+                              title: Text(AppLocalizations.of(context).success),
+                              content: Text(AppLocalizations.of(context).cacheWarning),
+                              actions: [
+                                TextButton(
+                                  child: Text(name),
+                                  onPressed: () {
+                                    Navigator.of(context).pop();
+                                    Navigator.pushReplacementNamed(
+                                        context, ExerciseDetailScreen.routeName,
+                                        arguments: base);
+                                  },
+                                ),
+                              ],
+                            );
+                          },
+                        );
+                      },
+                child: _isLoading
+                    ? const SizedBox(
+                        height: 20,
+                        width: 20,
+                        child: CircularProgressIndicator(),
+                      )
+                    : Text(AppLocalizations.of(context).save),
               )
             else
               ElevatedButton(