feat: add planning JSON exchange

LehrerApp.Desktop/ViewModels/Groups/PlanningViewModels.cs

@@ -49,6 +49,10 @@ public partial class PlanningTabViewModel : ObservableObject
     // Gruppenwechsel/Laden kurzzeitig null — ein verschachtelter Pfad würde dafür jedes Mal
     // einen Binding-Fehler loggen (siehe GroupDetailViewModel.IsDifferentiated für dasselbe Muster).
     public string SelectedUnitTitleSuffix => SelectedUnit is null ? "" : $" – {SelectedUnit.Title}";
+    public bool HasUnitSelection => SelectedUnit is not null;
+    public bool HasLessonSelection => SelectedLesson is not null;
+    public bool CanImportUnitPlanning => !IsReadOnly;
+    public bool CanImportLessonPlanning => !IsReadOnly && SelectedUnit is not null;
 
     public ObservableCollection<UnitSummary> Units { get; } = [];
     public ObservableCollection<LessonSummary> Lessons { get; } = [];
@@ -123,6 +127,8 @@ public partial class PlanningTabViewModel : ObservableObject
     {
         LoadLessons();
         OnPropertyChanged(nameof(SelectedUnitTitleSuffix));
+        OnPropertyChanged(nameof(HasUnitSelection));
+        OnPropertyChanged(nameof(CanImportLessonPlanning));
         EditUnitCommand.NotifyCanExecuteChanged();
         DeleteUnitCommand.NotifyCanExecuteChanged();
         CopyUnitCommand.NotifyCanExecuteChanged();
@@ -143,6 +149,7 @@ public partial class PlanningTabViewModel : ObservableObject
 
     partial void OnSelectedLessonChanged(LessonSummary? value)
     {
+        OnPropertyChanged(nameof(HasLessonSelection));
         ShowLessonCommand.NotifyCanExecuteChanged();
         EditLessonCommand.NotifyCanExecuteChanged();
         DeleteLessonCommand.NotifyCanExecuteChanged();
@@ -150,6 +157,23 @@ public partial class PlanningTabViewModel : ObservableObject
         AdvanceLessonStatusCommand.NotifyCanExecuteChanged();
     }
 
+    partial void OnIsReadOnlyChanged(bool value)
+    {
+        OnPropertyChanged(nameof(CanImportUnitPlanning));
+        OnPropertyChanged(nameof(CanImportLessonPlanning));
+    }
+
+    public void RefreshPlanning(Guid? selectUnitId = null, Guid? selectLessonId = null)
+    {
+        selectUnitId ??= SelectedUnit?.Id;
+        selectLessonId ??= SelectedLesson?.Id;
+        LoadUnits();
+        if (selectUnitId is Guid unitId)
+            SelectedUnit = Units.FirstOrDefault(u => u.Id == unitId) ?? SelectedUnit;
+        if (selectLessonId is Guid lessonId)
+            SelectedLesson = Lessons.FirstOrDefault(l => l.Id == lessonId);
+    }
+
     private bool HasSelectedUnit()   => SelectedUnit   is not null;
     private bool HasSelectedLesson() => SelectedLesson is not null;
     private bool CanAiAssist() => SelectedUnit is not null && _aiSettings.Enabled;