Intercepting containers for threads.

Wino.Mail.WinUI/Controls/ListView/WinoListView.cs

@@ -1,4 +1,5 @@
 using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
 using Wino.Mail.ViewModels.Data;
 
 namespace Wino.Mail.WinUI.Controls.ListView;
@@ -7,34 +8,70 @@ public partial class WinoListView : Microsoft.UI.Xaml.Controls.ListView
 {
     public bool IsAllSelected => Items.Count == SelectedItems.Count;
 
-    protected override DependencyObject GetContainerForItemOverride() => new WinoListViewItem();
+    public WinoListView()
+    {
+        ChoosingItemContainer += WinoListView_ChoosingItemContainer;
+    }
+
+    private void WinoListView_ChoosingItemContainer(ListViewBase sender, ChoosingItemContainerEventArgs args)
+    {
+        if (args.Item is ThreadMailItemViewModel)
+        {
+            args.ItemContainer = new WinoThreadMailItemViewModelListViewItem();
+        }
+        else if (args.Item is MailItemViewModel)
+        {
+            args.ItemContainer = new WinoMailItemViewModelListViewItem();
+        }
+
+        // Handle the preparation in PrepareContainerForItemOverride
+        args.IsContainerPrepared = false;
+    }
+
+    protected override void PrepareContainerForItemOverride(DependencyObject element, object item)
+    {
+        if (item is MailItemViewModel mailItemViewModel && element is WinoMailItemViewModelListViewItem container)
+        {
+            // Ensure the container's selection state matches the model's state
+            // This is crucial for virtualization scenarios where containers are recycled
+
+            container.IsSelected = mailItemViewModel.IsSelected;
+        }
+        else if (item is ThreadMailItemViewModel threadMailItemViewModel && element is WinoThreadMailItemViewModelListViewItem threadContainer)
+        {
+            threadContainer.IsThreadExpanded = threadMailItemViewModel.IsThreadExpanded;
+        }
+
+        base.PrepareContainerForItemOverride(element, item);
+    }
 
     public bool SelectMailItemContainer(MailItemViewModel mailItemViewModel)
     {
-        WinoListViewItem? itemContainer = null;
+        WinoMailItemViewModelListViewItem? itemContainer = null;
+        WinoThreadMailItemViewModelListViewItem? threadContainer = null;
 
         foreach (var item in Items)
         {
             if (item is MailItemViewModel mailItem && mailItem.Id == mailItemViewModel.Id)
             {
-                itemContainer = ContainerFromItem(mailItemViewModel) as WinoListViewItem;
+                itemContainer = ContainerFromItem(mailItemViewModel) as WinoMailItemViewModelListViewItem;
 
                 break;
             }
             else if (item is ThreadMailItemViewModel threadMailItemViewModel && threadMailItemViewModel.HasUniqueId(mailItemViewModel.MailCopy.UniqueId))
             {
-                itemContainer = ContainerFromItem(threadMailItemViewModel) as WinoListViewItem;
+                threadContainer = ContainerFromItem(threadMailItemViewModel) as WinoThreadMailItemViewModelListViewItem;
 
                 // Try to get the inner WinoListView.
-                if (itemContainer != null)
+                if (threadContainer != null)
                 {
-                    itemContainer.IsExpanded = true;
+                    threadContainer.IsThreadExpanded = true;
 
-                    var innerListViewControl = itemContainer.GetWinoListViewControl();
+                    var innerListViewControl = threadContainer.GetWinoListViewControl();
 
                     if (innerListViewControl != null)
                     {
-                        itemContainer = innerListViewControl.ContainerFromItem(mailItemViewModel) as WinoListViewItem;
+                        itemContainer = innerListViewControl.ContainerFromItem(mailItemViewModel) as WinoMailItemViewModelListViewItem;
                     }
                 }
 
@@ -42,8 +79,37 @@ public partial class WinoListView : Microsoft.UI.Xaml.Controls.ListView
             }
         }
 
-        itemContainer?.IsSelected = true;
+        if (itemContainer != null)
+        {
+            itemContainer.IsSelected = true;
+            return true;
+        }
+        else if (threadContainer != null)
+        {
+            return true;
+        }
 
-        return itemContainer != null;
+        return false;
+    }
+
+    public void ChangeSelectionMode(ListViewSelectionMode mode)
+    {
+        // Not only this control, but also all inner WinoListView controls should change the selection mode.
+        // TODO: New threads added after this call won't have the correct selection mode.
+
+        SelectionMode = mode;
+
+        foreach (var item in Items)
+        {
+            if (item is ThreadMailItemViewModel)
+            {
+                var itemContainer = ContainerFromItem(item) as WinoThreadMailItemViewModelListViewItem;
+                if (itemContainer != null)
+                {
+                    var innerListViewControl = itemContainer.GetWinoListViewControl();
+                    innerListViewControl?.ChangeSelectionMode(mode);
+                }
+            }
+        }
     }
 }