Email Confirmation and refactor for snackbar

frontend/pweb/lib/utils/snackbar.dart

@@ -2,28 +2,68 @@ import 'dart:async';
 
 import 'package:flutter/material.dart';
 
+import 'package:pweb/generated/i18n/app_localizations.dart';
 
-ScaffoldFeatureController<SnackBar, SnackBarClosedReason> notifyUserX(
-  ScaffoldMessengerState sm, 
-  String message, 
-  { int delaySeconds = 3 }
-) => sm.showSnackBar(SnackBar(content: Text(message), duration: Duration(seconds: delaySeconds)));
 
-ScaffoldFeatureController<SnackBar, SnackBarClosedReason> notifyUser(
-  BuildContext context, 
-  String message, 
-  { int delaySeconds = 3 }
-) => notifyUserX(ScaffoldMessenger.of(context), message, delaySeconds: delaySeconds);
+Future<void> notifyUserX(
+  BuildContext context,
+  String message, {
+  int delaySeconds = 3,
+}) async {
+  if (!context.mounted) return;
+  final scaffoldMessenger = ScaffoldMessenger.maybeOf(context);
+  if (scaffoldMessenger != null) {
+    scaffoldMessenger.showSnackBar(
+      SnackBar(
+        content: Text(message),
+        duration: Duration(seconds: delaySeconds),
+      ),
+    );
+    return;
+  }
 
-Future<ScaffoldFeatureController<SnackBar, SnackBarClosedReason>> postNotifyUser(
-  BuildContext context, String message, {int delaySeconds = 3}) {
+  await _showMessageDialog(context, message);
+}
 
-  final completer = Completer<ScaffoldFeatureController<SnackBar, SnackBarClosedReason>>();
+Future<void> notifyUser(
+  BuildContext context,
+  String message, {
+  int delaySeconds = 3,
+}) =>
+    notifyUserX(context, message, delaySeconds: delaySeconds);
 
-  WidgetsBinding.instance.addPostFrameCallback((_) {
-    final controller = notifyUser(context, message, delaySeconds: delaySeconds);
-    completer.complete(controller);
+Future<void> postNotifyUser(
+  BuildContext context,
+  String message, {
+  int delaySeconds = 3,
+}) {
+  final completer = Completer<void>();
+
+  WidgetsBinding.instance.addPostFrameCallback((_) async {
+    if (!context.mounted) {
+      completer.complete();
+      return;
+    }
+    await notifyUser(context, message, delaySeconds: delaySeconds);
+    completer.complete();
   });
 
   return completer.future;
 }
+
+Future<void> _showMessageDialog(BuildContext context, String message) async {
+  if (!context.mounted) return;
+  final loc = AppLocalizations.of(context)!;
+  await showDialog<void>(
+    context: context,
+    builder: (dialogContext) => AlertDialog(
+      title: Text(message),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.of(dialogContext).pop(),
+          child: Text(loc.ok),
+        ),
+      ],
+    ),
+  );
+}