LehrerApp/LehrerApp.Desktop/Views/Groups/SeatingPlanTabView.axaml

<UserControl 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.SeatingPlanTabView"
             x:DataType="vm:SeatingPlanTabViewModel">
  <UserControl.Styles>
    <Style Selector="Border.seat">
      <Setter Property="Background" Value="{DynamicResource SystemControlBackgroundAltHighBrush}"/>
      <Setter Property="BorderBrush" Value="{DynamicResource SystemControlForegroundBaseLowBrush}"/>
      <Setter Property="BorderThickness" Value="1"/>
    </Style>
    <Style Selector="Border.seat.occupied">
      <Setter Property="BorderBrush" Value="{DynamicResource SystemAccentColor}"/>
    </Style>
    <Style Selector="Border.seat.droptarget">
      <Setter Property="Background" Value="{DynamicResource SystemAccentColorLight2}"/>
      <Setter Property="BorderBrush" Value="{DynamicResource SystemAccentColor}"/>
      <Setter Property="BorderThickness" Value="2"/>
    </Style>
  </UserControl.Styles>
  <Grid ColumnDefinitions="260,*">
    <Border Grid.Column="0" BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
            BorderThickness="0,0,1,0" Padding="16">
      <Grid RowDefinitions="Auto,*,Auto">
        <StackPanel Grid.Row="0" Spacing="4" Margin="0,0,0,12">
          <TextBlock Text="Sitzpläne" FontSize="18" FontWeight="SemiBold"/>
          <TextBlock Text="Mehrere Pläne, z. B. für verschiedene Räume" FontSize="12"
                     Opacity="0.6" TextWrapping="Wrap"/>
        </StackPanel>
        <ListBox Grid.Row="1" ItemsSource="{Binding Plans}" SelectedItem="{Binding SelectedPlan}">
          <ListBox.ItemTemplate>
            <DataTemplate x:DataType="vm:SeatingPlanSummary">
              <StackPanel Margin="4,6" Spacing="2">
                <TextBlock Text="{Binding Name}" FontWeight="SemiBold"/>
                <TextBlock Text="{Binding RoomDisplay}" FontSize="12" Opacity="0.6"/>
              </StackPanel>
            </DataTemplate>
          </ListBox.ItemTemplate>
        </ListBox>
        <StackPanel Grid.Row="2" Spacing="8" Margin="0,12,0,0">
          <Button Content="＋ Sitzplan" Command="{Binding AddPlanCommand}" HorizontalAlignment="Stretch"/>
          <Grid ColumnDefinitions="*,8,*" IsVisible="{Binding HasSelectedPlan}">
            <Button Grid.Column="0" Content="Bearbeiten" Command="{Binding EditPlanCommand}"
                    HorizontalAlignment="Stretch"/>
            <Button Grid.Column="2" Content="Löschen" Command="{Binding DeletePlanCommand}"
                    HorizontalAlignment="Stretch"/>
          </Grid>
        </StackPanel>
      </Grid>
    </Border>

    <Grid Grid.Column="1">
      <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center" Spacing="10"
                  IsVisible="{Binding HasPlans, Converter={x:Static BoolConverters.Not}}">
        <TextBlock Text="Noch kein Sitzplan" FontSize="20" FontWeight="SemiBold"
                   HorizontalAlignment="Center"/>
        <TextBlock Text="Lege einen Plan an und ordne die Schüler den Plätzen zu."
                   Opacity="0.6" TextAlignment="Center"/>
        <Button Content="Ersten Sitzplan anlegen" Command="{Binding AddPlanCommand}"
                HorizontalAlignment="Center"/>
      </StackPanel>

      <Grid RowDefinitions="Auto,*" IsVisible="{Binding HasSelectedPlan}" Margin="24">
        <Grid Grid.Row="0" ColumnDefinitions="*,Auto" Margin="0,0,0,18">
          <StackPanel Spacing="3">
            <TextBlock Text="{Binding PlanTitle}" FontSize="22" FontWeight="SemiBold"/>
            <TextBlock Text="{Binding PlanSubtitle}" Opacity="0.65"/>
          </StackPanel>
          <StackPanel Grid.Column="1" VerticalAlignment="Bottom">
            <TextBlock Text="{Binding AssignmentSummary}" HorizontalAlignment="Right" FontSize="12" Opacity="0.6"/>
            <TextBlock Text="Ziehen: Platz ändern · Klicken: bewerten" HorizontalAlignment="Right"
                       FontSize="11" Opacity="0.5"/>
          </StackPanel>
        </Grid>

        <ScrollViewer Grid.Row="1" HorizontalScrollBarVisibility="Auto"
                      VerticalScrollBarVisibility="Auto">
          <StackPanel Spacing="14" HorizontalAlignment="Center">
            <Border Background="{DynamicResource SystemControlBackgroundChromeMediumLowBrush}"
                    CornerRadius="6" Padding="36,8" HorizontalAlignment="Center">
              <TextBlock Text="Tafel / Vorderseite" FontWeight="SemiBold" Opacity="0.75"/>
            </Border>
            <ItemsControl ItemsSource="{Binding Seats}" HorizontalAlignment="Center">
              <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                  <UniformGrid Columns="{Binding PlanColumns}"/>
                </ItemsPanelTemplate>
              </ItemsControl.ItemsPanel>
              <ItemsControl.ItemTemplate>
                <DataTemplate x:DataType="vm:SeatCellViewModel">
                  <Border Classes="seat" Classes.occupied="{Binding IsOccupied}"
                          Classes.droptarget="{Binding IsDropTarget}"
                          Width="190" MinHeight="76" Margin="5" Padding="10"
                          CornerRadius="7"
                          DragDrop.AllowDrop="True"
                          DragDrop.DragEnter="OnSeatDragEnter"
                          DragDrop.DragLeave="OnSeatDragLeave"
                          DragDrop.DragOver="OnSeatDragOver"
                          DragDrop.Drop="OnSeatDrop"
                          PointerPressed="OnDragSourcePressed"
                          PointerMoved="OnDragSourceMoved"
                          PointerReleased="OnDragSourceReleased"
                          Tapped="OnSeatTapped">
                    <StackPanel Spacing="5">
                      <Grid ColumnDefinitions="*,Auto">
                        <TextBlock Text="{Binding PositionLabel}" FontSize="10" Opacity="0.5"/>
                        <TextBlock Grid.Column="1" Text="⠿" Opacity="0.45" IsVisible="{Binding IsOccupied}"/>
                      </Grid>
                      <TextBlock Text="{Binding StudentName}" FontWeight="SemiBold" FontSize="13"
                                 HorizontalAlignment="Center" VerticalAlignment="Center"/>
                    </StackPanel>
                  </Border>
                </DataTemplate>
              </ItemsControl.ItemTemplate>
            </ItemsControl>

            <Border DragDrop.AllowDrop="True" DragDrop.DragOver="OnUnassignedDragOver"
                    DragDrop.Drop="OnUnassignedDrop"
                    BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
                    BorderThickness="1" CornerRadius="7" Padding="12" Margin="5,8">
              <StackPanel Spacing="8">
                <TextBlock Text="NICHT ZUGEORDNET" FontSize="10" FontWeight="Bold" Opacity="0.5"/>
                <TextBlock Text="Schüler hierher ziehen, um einen Platz zu leeren."
                           FontSize="11" Opacity="0.5"/>
                <ItemsControl ItemsSource="{Binding UnassignedStudents}">
                  <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate><WrapPanel/></ItemsPanelTemplate>
                  </ItemsControl.ItemsPanel>
                  <ItemsControl.ItemTemplate>
                    <DataTemplate x:DataType="vm:StudentSeatOption">
                      <Border Background="{DynamicResource SystemAccentColorLight2}" CornerRadius="5"
                              Padding="9,5" Margin="0,0,6,6"
                              PointerPressed="OnDragSourcePressed"
                              PointerMoved="OnDragSourceMoved"
                              PointerReleased="OnDragSourceReleased">
                        <TextBlock Text="{Binding DisplayName}" FontSize="12"/>
                      </Border>
                    </DataTemplate>
                  </ItemsControl.ItemTemplate>
                </ItemsControl>
                <TextBlock Text="Alle Schüler sind zugeordnet." Classes="emptyhint"
                           IsVisible="{Binding !UnassignedStudents.Count}"/>
              </StackPanel>
            </Border>
          </StackPanel>
        </ScrollViewer>
      </Grid>
    </Grid>
  </Grid>
</UserControl>