Klausurverwaltung: Anlegen, Bearbeiten, Duplizieren, Status, Aufgaben

Implementiert TODO 1.1 (Klausur anlegen/verwalten) und die dazu passenden
Teile von 1.2 (Aufgabenstruktur), da beides im selben Dialog verwaltet wird:

- ExamDialog: Klausur anlegen/bearbeiten/duplizieren mit Aufgaben-Editor
  (Nr./Titel/Maximalpunkte/Gewichtung, sortierbar), Gesamtpunkte-Anzeige
  mit Warnung bei 0 Punkten, und Kompetenz-Zuordnung je Aufgabe.
- Klausuren-Tab: Kontextmenü und Toolbar für Bearbeiten/Duplizieren/
  Löschen (mit Rückfrage), farbcodierte Status-Spalte, SplitButton für
  Statuswechsel (Klick = nächster Status, Dropdown = manuelles Setzen).
- ExamRepository.Delete löscht zugehörige ExamResults kaskadierend.
- Gewichtung ist standardmäßig ausgeblendet (Checkbox zum Einblenden),
  NumericUpDown-Felder ohne Spinner-Buttons wegen eines Layout-Bugs im
  Avalonia-Standardtemplate, der das interne Textfeld auf wenige Pixel
  schrumpfen ließ.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

LehrerApp.Desktop/Views/Groups/DeleteExamDialog.axaml

@@ -0,0 +1,20 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        x:Class="LehrerApp.Desktop.Views.Groups.DeleteExamDialog"
+        x:CompileBindings="False"
+        Title="Klausur löschen"
+        Width="430" SizeToContent="Height"
+        CanResize="False" WindowStartupLocation="CenterOwner">
+  <Grid RowDefinitions="*,Auto" Margin="24">
+    <StackPanel Grid.Row="0" Spacing="12">
+      <TextBlock Text="Klausur wirklich löschen?" FontSize="18" FontWeight="SemiBold"/>
+      <TextBlock Text="{Binding}" FontSize="15" FontWeight="SemiBold" TextWrapping="Wrap"/>
+      <TextBlock Text="Dabei werden auch alle erfassten Ergebnisse dieser Klausur dauerhaft gelöscht."
+                 TextWrapping="Wrap" Opacity="0.7"/>
+    </StackPanel>
+    <Grid Grid.Row="1" ColumnDefinitions="*,8,*" Margin="0,20,0,0">
+      <Button Grid.Column="0" Content="Abbrechen" HorizontalAlignment="Stretch" Click="OnCancel"/>
+      <Button Grid.Column="2" Content="Endgültig löschen" HorizontalAlignment="Stretch" Click="OnDelete"/>
+    </Grid>
+  </Grid>
+</Window>

LehrerApp.Desktop/Views/Groups/DeleteExamDialog.axaml.cs

@@ -0,0 +1,12 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+
+namespace LehrerApp.Desktop.Views.Groups;
+
+public partial class DeleteExamDialog : Window
+{
+    public DeleteExamDialog() => InitializeComponent();
+
+    private void OnDelete(object? sender, RoutedEventArgs e) => Close(true);
+    private void OnCancel(object? sender, RoutedEventArgs e) => Close(false);
+}

LehrerApp.Desktop/Views/Groups/ExamDialog.axaml

@@ -0,0 +1,121 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels.Groups"
+        x:Class="LehrerApp.Desktop.Views.Groups.ExamDialog"
+        x:DataType="vm:ExamDialogViewModel"
+        Title="{Binding DialogTitle}"
+        Width="640" Height="680" MinWidth="560" MinHeight="420"
+        CanResize="True" WindowStartupLocation="CenterOwner">
+
+  <Grid RowDefinitions="*,Auto" Margin="24">
+    <ScrollViewer Grid.Row="0">
+      <StackPanel Spacing="14" Margin="0,0,12,0">
+        <TextBlock Text="{Binding DialogTitle}" FontSize="18" FontWeight="SemiBold"/>
+
+        <StackPanel Spacing="4">
+          <TextBlock Text="Titel *" FontSize="12" Opacity="0.7"/>
+          <TextBox Text="{Binding Title}" PlaceholderText="z.B. 1. Klausur Kinetik"/>
+        </StackPanel>
+
+        <Grid ColumnDefinitions="*,12,*,12,*">
+          <StackPanel Grid.Column="0" Spacing="4">
+            <TextBlock Text="Datum *" FontSize="12" Opacity="0.7"/>
+            <TextBox Text="{Binding DateText}" PlaceholderText="TT.MM.JJJJ"/>
+          </StackPanel>
+          <StackPanel Grid.Column="2" Spacing="4">
+            <TextBlock Text="Fach" FontSize="12" Opacity="0.7"/>
+            <TextBox Text="{Binding Subject}"/>
+          </StackPanel>
+          <StackPanel Grid.Column="4" Spacing="4">
+            <TextBlock Text="Klausurnummer" FontSize="12" Opacity="0.7"/>
+            <NumericUpDown Value="{Binding ExamNumber}" Minimum="1" Maximum="20" FormatString="0"
+                           ShowButtonSpinner="False"/>
+          </StackPanel>
+        </Grid>
+
+        <StackPanel Spacing="4">
+          <TextBlock Text="Notizen" FontSize="12" Opacity="0.7"/>
+          <TextBox Text="{Binding Notes}" AcceptsReturn="True" Height="56" TextWrapping="Wrap"/>
+        </StackPanel>
+
+        <Separator Margin="0,4"/>
+
+        <Grid ColumnDefinitions="*,Auto">
+          <TextBlock Grid.Column="0" Text="Aufgaben" FontSize="14" FontWeight="SemiBold" VerticalAlignment="Center"/>
+          <Button Grid.Column="1" Content="＋ Aufgabe" Command="{Binding AddTaskCommand}"/>
+        </Grid>
+
+        <CheckBox Content="Gewichtung verwenden" IsChecked="{Binding UseWeighting}"/>
+
+        <Grid ColumnDefinitions="*,Auto">
+          <TextBlock Grid.Column="0" Text="{Binding TotalPointsDisplay}" FontSize="12" Opacity="0.7"
+                     VerticalAlignment="Center"/>
+          <TextBlock Grid.Column="1" Text="Achtung: noch keine Punkte vergeben" Foreground="Red" FontSize="12"
+                     IsVisible="{Binding TotalPointsWarning}" VerticalAlignment="Center"/>
+        </Grid>
+
+        <ItemsControl ItemsSource="{Binding Tasks}">
+          <ItemsControl.ItemTemplate>
+            <DataTemplate x:DataType="vm:ExamTaskEditItem">
+              <Border BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+                      BorderThickness="1" CornerRadius="4" Padding="8" Margin="0,0,0,6">
+                <StackPanel Spacing="6">
+                  <Grid ColumnDefinitions="26,*,Auto,Auto,Auto,Auto,Auto">
+                    <TextBlock Grid.Column="0" Text="{Binding Nr}" VerticalAlignment="Center" Opacity="0.6"/>
+                    <TextBox Grid.Column="1" Text="{Binding Title}" PlaceholderText="Titel der Aufgabe" Margin="0,0,6,0"/>
+                    <NumericUpDown Grid.Column="2" Value="{Binding MaxPoints}" Minimum="0" FormatString="0.##"
+                                   Width="72" ShowButtonSpinner="False" Margin="0,0,6,0" ToolTip.Tip="Maximalpunkte"/>
+                    <NumericUpDown Grid.Column="3" Value="{Binding Weight}" Minimum="0" FormatString="0.##"
+                                   Width="72" ShowButtonSpinner="False" Margin="0,0,6,0" ToolTip.Tip="Gewichtung"
+                                   IsVisible="{Binding ShowWeight}"/>
+                    <Button Grid.Column="4" Content="↑" Command="{Binding MoveUpCommand}" Padding="6,2"
+                            ToolTip.Tip="Nach oben"/>
+                    <Button Grid.Column="5" Content="↓" Command="{Binding MoveDownCommand}" Padding="6,2"
+                            ToolTip.Tip="Nach unten" Margin="4,0,0,0"/>
+                    <Button Grid.Column="6" Content="✕" Command="{Binding RemoveCommand}" Padding="6,2"
+                            ToolTip.Tip="Entfernen" Margin="4,0,0,0"/>
+                  </Grid>
+
+                  <Button Content="{Binding CompetencySummary}" Command="{Binding ToggleCompetencyPanelCommand}"
+                          HorizontalAlignment="Left" FontSize="11" Padding="6,2"/>
+
+                  <ItemsControl ItemsSource="{Binding CompetencyTagGroups}" IsVisible="{Binding IsCompetencyPanelOpen}">
+                    <ItemsControl.ItemTemplate>
+                      <DataTemplate x:DataType="vm:CompetencyTagGroup">
+                        <StackPanel Margin="12,2">
+                          <TextBlock Text="{Binding DisplayName}" FontSize="11" Opacity="0.6"/>
+                          <ItemsControl ItemsSource="{Binding Items}">
+                            <ItemsControl.ItemsPanel>
+                              <ItemsPanelTemplate>
+                                <WrapPanel/>
+                              </ItemsPanelTemplate>
+                            </ItemsControl.ItemsPanel>
+                            <ItemsControl.ItemTemplate>
+                              <DataTemplate x:DataType="vm:CompetencyTag">
+                                <ToggleButton Content="{Binding Display}" IsChecked="{Binding IsSelected}"
+                                              Margin="0,2,6,2" FontSize="11" Padding="6,2"/>
+                              </DataTemplate>
+                            </ItemsControl.ItemTemplate>
+                          </ItemsControl>
+                        </StackPanel>
+                      </DataTemplate>
+                    </ItemsControl.ItemTemplate>
+                  </ItemsControl>
+                </StackPanel>
+              </Border>
+            </DataTemplate>
+          </ItemsControl.ItemTemplate>
+        </ItemsControl>
+
+        <TextBlock Text="{Binding ValidationMessage}" Foreground="Red" FontSize="12"
+                   IsVisible="{Binding ValidationMessage, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+      </StackPanel>
+    </ScrollViewer>
+
+    <Grid Grid.Row="1" ColumnDefinitions="*,8,*" Margin="0,20,0,0">
+      <Button Grid.Column="0" Content="Abbrechen" HorizontalAlignment="Stretch" Click="OnCancel"/>
+      <Button Grid.Column="2" Content="{Binding SaveButtonText}"
+              HorizontalAlignment="Stretch" Click="OnSave"/>
+    </Grid>
+  </Grid>
+</Window>

LehrerApp.Desktop/Views/Groups/ExamDialog.axaml.cs

@@ -0,0 +1,21 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using LehrerApp.Desktop.ViewModels.Groups;
+
+namespace LehrerApp.Desktop.Views.Groups;
+
+public partial class ExamDialog : Window
+{
+    public ExamDialog() => InitializeComponent();
+
+    private void OnSave(object? s, RoutedEventArgs e)
+    {
+        if (DataContext is ExamDialogViewModel vm && vm.SaveCommand.CanExecute(null))
+        {
+            vm.SaveCommand.Execute(null);
+            if (vm.Result is not null) Close(true);
+        }
+    }
+
+    private void OnCancel(object? s, RoutedEventArgs e) => Close(false);
+}

LehrerApp.Desktop/Views/Groups/GroupDetailView.axaml

@@ -2,6 +2,7 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels.Groups"
              xmlns:views="clr-namespace:LehrerApp.Desktop.Views.Groups"
+             xmlns:models="clr-namespace:LehrerApp.Core.Models;assembly=LehrerApp.Core"
              x:Class="LehrerApp.Desktop.Views.Groups.GroupDetailView"
              x:DataType="vm:GroupDetailViewModel">
 
@@ -66,17 +67,69 @@
 
       <!-- Tab: Klausuren -->
       <ContentPage Header="Klausuren">
-        <DataGrid ItemsSource="{Binding Exams}"
-                  AutoGenerateColumns="False"
-                  IsReadOnly="True"
-                  GridLinesVisibility="Horizontal"
-                  CanUserReorderColumns="False">
-          <DataGrid.Columns>
-            <DataGridTextColumn Header="Datum"  Binding="{Binding Date}"        Width="110"/>
-            <DataGridTextColumn Header="Titel"  Binding="{Binding Title}"       Width="*"/>
-            <DataGridTextColumn Header="Status" Binding="{Binding StatusLabel}" Width="130"/>
-          </DataGrid.Columns>
-        </DataGrid>
+        <Grid RowDefinitions="Auto,*">
+          <StackPanel Grid.Row="0" Orientation="Horizontal" Spacing="8" Margin="0,0,0,8"
+                      IsVisible="{Binding SelectedExam, Converter={x:Static ObjectConverters.IsNotNull}}">
+            <Button Content="Bearbeiten"    Command="{Binding EditExamCommand}"/>
+            <Button Content="Duplizieren"   Command="{Binding DuplicateExamCommand}"/>
+            <SplitButton Content="Status ▸" Command="{Binding AdvanceExamStatusCommand}">
+              <SplitButton.Flyout>
+                <MenuFlyout Placement="BottomEdgeAlignedLeft">
+                  <MenuItem Header="Geplant"       Command="{Binding SetExamStatusCommand}"
+                            CommandParameter="{x:Static models:ExamStatus.Planned}"/>
+                  <MenuItem Header="Durchgeführt"  Command="{Binding SetExamStatusCommand}"
+                            CommandParameter="{x:Static models:ExamStatus.Conducted}"/>
+                  <MenuItem Header="Korrigiert"    Command="{Binding SetExamStatusCommand}"
+                            CommandParameter="{x:Static models:ExamStatus.Graded}"/>
+                  <MenuItem Header="Zurückgegeben" Command="{Binding SetExamStatusCommand}"
+                            CommandParameter="{x:Static models:ExamStatus.Returned}"/>
+                </MenuFlyout>
+              </SplitButton.Flyout>
+            </SplitButton>
+            <Button Content="Löschen"       Command="{Binding DeleteExamCommand}"/>
+          </StackPanel>
+          <DataGrid Grid.Row="1" ItemsSource="{Binding Exams}"
+                    SelectedItem="{Binding SelectedExam}"
+                    AutoGenerateColumns="False"
+                    IsReadOnly="True"
+                    GridLinesVisibility="Horizontal"
+                    CanUserReorderColumns="False">
+            <DataGrid.Columns>
+              <DataGridTextColumn Header="Datum"  Binding="{Binding Date}"  Width="110"/>
+              <DataGridTextColumn Header="Titel"  Binding="{Binding Title}" Width="*"/>
+              <DataGridTemplateColumn Header="Status" Width="150">
+                <DataGridTemplateColumn.CellTemplate>
+                  <DataTemplate x:DataType="vm:ExamSummary">
+                    <Border Background="{Binding StatusColorHex}" CornerRadius="4"
+                            Padding="8,2" HorizontalAlignment="Left">
+                      <TextBlock Text="{Binding StatusLabel}" FontSize="12" Foreground="White"/>
+                    </Border>
+                  </DataTemplate>
+                </DataGridTemplateColumn.CellTemplate>
+              </DataGridTemplateColumn>
+            </DataGrid.Columns>
+            <DataGrid.ContextMenu>
+              <ContextMenu>
+                <MenuItem Header="Bearbeiten"    Command="{Binding EditExamCommand}"/>
+                <MenuItem Header="Duplizieren"   Command="{Binding DuplicateExamCommand}"/>
+                <MenuItem Header="Status">
+                  <MenuItem Header="Weiter" Command="{Binding AdvanceExamStatusCommand}"/>
+                  <Separator/>
+                  <MenuItem Header="Geplant"       Command="{Binding SetExamStatusCommand}"
+                            CommandParameter="{x:Static models:ExamStatus.Planned}"/>
+                  <MenuItem Header="Durchgeführt"  Command="{Binding SetExamStatusCommand}"
+                            CommandParameter="{x:Static models:ExamStatus.Conducted}"/>
+                  <MenuItem Header="Korrigiert"    Command="{Binding SetExamStatusCommand}"
+                            CommandParameter="{x:Static models:ExamStatus.Graded}"/>
+                  <MenuItem Header="Zurückgegeben" Command="{Binding SetExamStatusCommand}"
+                            CommandParameter="{x:Static models:ExamStatus.Returned}"/>
+                </MenuItem>
+                <Separator/>
+                <MenuItem Header="Löschen"       Command="{Binding DeleteExamCommand}"/>
+              </ContextMenu>
+            </DataGrid.ContextMenu>
+          </DataGrid>
+        </Grid>
       </ContentPage>
 
       <!-- Tab: Noten -->

LehrerApp.Desktop/Views/Groups/GroupDetailView.axaml.cs

@@ -1,5 +1,6 @@
 using Avalonia.Controls;
 using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
 using LehrerApp.Desktop.ViewModels.Groups;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -13,7 +14,13 @@ public partial class GroupDetailView : UserControl
     {
         base.OnDataContextChanged(e);
         if (DataContext is GroupDetailViewModel vm)
-            vm.OnAddStudent = ShowAddStudentDialog;
+        {
+            vm.OnAddStudent      = ShowAddStudentDialog;
+            vm.OnAddExam         = ShowAddExamDialog;
+            vm.OnEditExam        = ShowEditExamDialog;
+            vm.OnDuplicateExam   = ShowDuplicateExamDialog;
+            vm.OnConfirmDeleteExam = ShowDeleteExamDialog;
+        }
     }
 
     private async Task<bool> ShowAddStudentDialog()
@@ -32,4 +39,37 @@ public partial class GroupDetailView : UserControl
 
         return await dialog.ShowDialog<bool>(owner);
     }
+
+    private Task<bool> ShowAddExamDialog(Guid groupId) =>
+        ShowExamDialog(groupId, editingExam: null, duplicateSource: null);
+
+    private Task<bool> ShowEditExamDialog(Exam exam) =>
+        ShowExamDialog(exam.GroupId, editingExam: exam, duplicateSource: null);
+
+    private Task<bool> ShowDuplicateExamDialog(Exam exam) =>
+        ShowExamDialog(exam.GroupId, editingExam: null, duplicateSource: exam);
+
+    private async Task<bool> ShowExamDialog(Guid groupId, Exam? editingExam, Exam? duplicateSource)
+    {
+        if (DataContext is not GroupDetailViewModel vm || vm.Group is null) return false;
+
+        var dialogVm = new ExamDialogViewModel(
+            App.Services.GetRequiredService<IExamRepository>(),
+            App.Services.GetRequiredService<ICompetencyDomainRepository>(),
+            groupId, vm.Group.SubjectId, vm.Group.GradeLevel, vm.Group.GradingSystem,
+            vm.Group.Subject ?? "", editingExam, duplicateSource);
+
+        var dialog = new ExamDialog { DataContext = dialogVm };
+        var owner = TopLevel.GetTopLevel(this) as Window;
+        if (owner is null) return false;
+
+        return await dialog.ShowDialog<bool>(owner);
+    }
+
+    private async Task<bool> ShowDeleteExamDialog(ExamSummary exam)
+    {
+        var dialog = new DeleteExamDialog { DataContext = exam.Title };
+        var owner = TopLevel.GetTopLevel(this) as Window;
+        return owner is not null && await dialog.ShowDialog<bool>(owner);
+    }
 }