feat(#259): controll that tutorial only opens once

app/lib/common/widgets/module.dart

@@ -27,4 +27,4 @@ export 'rounded_card.dart';
 export 'scroll_list.dart';
 export 'subheader_divider.dart';
 export 'tutorial/content.dart';
-export 'tutorial/show.dart';
+export 'tutorial/controller.dart';

app/lib/common/widgets/tutorial/controller.dart

@@ -0,0 +1,43 @@
+import 'dart:async';
+
+import '../../module.dart';
+import 'container.dart';
+
+class TutorialController {
+  factory TutorialController() {
+    return _instance;
+  }
+  TutorialController._();
+  static final TutorialController _instance = TutorialController._();
+
+  bool _isOpen = false;
+
+  FutureOr<void> showTutorial({
+    required BuildContext context,
+    required List<TutorialContent> pages,
+    String? lastNextButtonText,
+    FutureOr<void> Function()? onClose,
+  }) {
+    if (_isOpen) return null;
+    _isOpen = true;
+    return showModalBottomSheet(
+      context: context,
+      enableDrag: true,
+      showDragHandle: true,
+      isDismissible: false,
+      isScrollControlled: true,
+      useSafeArea: true,
+      elevation: 0,
+      builder: (context) => TutorialContainer(
+        pages: pages,
+        lastNextButtonText: lastNextButtonText,
+        finishTutorial: () async {
+          final closeTutorial = Navigator.of(context).pop;
+          if (onClose != null) await onClose();
+          _isOpen = false;
+          closeTutorial();
+        },
+      ),
+    );
+  }
+}

app/lib/drug_selection/pages/drug_selection.dart

@@ -27,7 +27,7 @@ class DrugSelectionPage extends HookWidget {
               MetaData.instance.initialDrugSelectionInitiated ?? false;
             if (concludesOnboarding && !initialDrugSelectionInitiated) {
               WidgetsBinding.instance.addPostFrameCallback((_) async {
-                await showTutorial(
+                await TutorialController().showTutorial(
                   context: context,
                   pages: [
                     TutorialContent(
@@ -38,8 +38,10 @@ class DrugSelectionPage extends HookWidget {
                       ),
                     ),
                   ],
-                  updateMetadata: () =>
-                    MetaData.instance.initialDrugSelectionInitiated = true,
+                  onClose: () async {
+                    MetaData.instance.initialDrugSelectionInitiated = true;
+                    await MetaData.save();
+                  }
                 );
               });
             }