fix: Briefe Kontaktauswahl

LehrerApp.Desktop/ViewModels/Students/CreateLetterDialogViewModel.cs

@@ -44,6 +44,8 @@ public partial class CreateLetterDialogViewModel : ObservableObject
     public bool HasCustomPlaceholders => CustomPlaceholders.Count > 0;
     public bool HasNoTemplates => Templates.Count == 0;
     public bool HasNoContacts => Contacts.Count == 0;
+    public string AddressPreview => LetterPlaceholderBuilder.FormatAddress(SelectedContact?.Model);
+    public bool HasAddressPreview => !string.IsNullOrWhiteSpace(AddressPreview);
     public bool UsesAttendanceAdvancedContent => UsesAttendanceCalendar || UsesAbsenceDayList;
     public string SuggestedFileName => SanitizeFileName(
         $"{SelectedTemplate?.Name ?? "Elternbrief"}_{_student.LastName}_{_student.FirstName}.pdf");
@@ -82,6 +84,8 @@ public partial class CreateLetterDialogViewModel : ObservableObject
     partial void OnSelectedContactChanged(LetterContactChoice? value)
     {
         Anrede = value?.Model.LetterSalutation ?? "";
+        OnPropertyChanged(nameof(AddressPreview));
+        OnPropertyChanged(nameof(HasAddressPreview));
         RefreshValidation();
     }
     partial void OnAnredeChanged(string value) => RefreshValidation();

LehrerApp.Desktop/ViewModels/Students/SelectContactDialogViewModel.cs

@@ -0,0 +1,25 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using LehrerApp.Desktop.Services;
+
+namespace LehrerApp.Desktop.ViewModels.Students;
+
+public partial class SelectContactDialogViewModel : ObservableObject
+{
+    [ObservableProperty] private LetterContactChoice? _selectedContact;
+
+    public IReadOnlyList<LetterContactChoice> Contacts { get; }
+    public string AddressPreview => LetterPlaceholderBuilder.FormatAddress(SelectedContact?.Model);
+    public bool HasAddressPreview => !string.IsNullOrWhiteSpace(AddressPreview);
+
+    public SelectContactDialogViewModel(IReadOnlyList<LetterContactChoice> contacts, LetterContactChoice? current)
+    {
+        Contacts = contacts;
+        SelectedContact = current ?? contacts.FirstOrDefault();
+    }
+
+    partial void OnSelectedContactChanged(LetterContactChoice? value)
+    {
+        OnPropertyChanged(nameof(AddressPreview));
+        OnPropertyChanged(nameof(HasAddressPreview));
+    }
+}