More selection edge cases fixed

Toolkit.Foundation/ObservableCollection.cs

@@ -29,7 +29,8 @@ public partial class ObservableCollection<TItem> :
     INotificationHandler<InsertEventArgs<TItem>>,
     INotificationHandler<MoveEventArgs<TItem>>,
     INotificationHandler<MoveToEventArgs<TItem>>,
-    INotificationHandler<ReplaceEventArgs<TItem>>
+    INotificationHandler<ReplaceEventArgs<TItem>>,
+    INotificationHandler<SelectionEventArgs<TItem>>
     where TItem :
     IDisposable
 {
@@ -43,6 +44,9 @@ public partial class ObservableCollection<TItem> :
     [ObservableProperty]
     private int selectedIndex = 0;
 
+    [ObservableProperty]
+    private TItem? selectedItem;
+
     public ObservableCollection(IServiceProvider provider,
         IServiceFactory factory,
         IMediator mediator,
@@ -279,6 +283,15 @@ public partial class ObservableCollection<TItem> :
         if (args.Value is TItem item)
         {
             Insert(args.Index, item);
+
+            if (item is ISelectable selectable)
+            {
+                if (selectable.Selected)
+                {
+                    SelectedItem = item;
+                    SelectedIndex = this.IndexOf(item);
+                }
+            }
         }
 
         return Task.CompletedTask;
@@ -487,6 +500,11 @@ public partial class ObservableCollection<TItem> :
             added.Selected = true;
         }
     }
+
+    public Task Handle(SelectionEventArgs<TItem> args)
+    {
+        return Task.CompletedTask;
+    }
 }
 
 public partial class ObservableCollection<TValue, TViewModel>(IServiceProvider provider,

Toolkit.Foundation/Selected.cs

@@ -1,10 +0,0 @@
-namespace Toolkit.Foundation;
-
-public record Selected
-{
-    public static SelectedEventArgs<TValue> As<TValue>(TValue value) =>
-        new(value);
-
-    public static SelectedEventArgs<TValue> As<TValue>() where TValue : new() =>
-        new(new TValue());
-}

Toolkit.Foundation/SelectedEventArgs.cs

@@ -1,3 +0,0 @@
-namespace Toolkit.Foundation;
-
-public record SelectedEventArgs<TValue>(TValue? Value);

Toolkit.Foundation/Selection.cs

@@ -0,0 +1,10 @@
+namespace Toolkit.Foundation;
+
+public record Selection
+{
+    public static SelectionEventArgs<TValue> As<TValue>(TValue value) =>
+        new(value);
+
+    public static SelectionEventArgs<TValue> As<TValue>() where TValue : new() =>
+        new(new TValue());
+}

Toolkit.Foundation/SelectionEventArgs.cs

@@ -0,0 +1,3 @@
+namespace Toolkit.Foundation;
+
+public record SelectionEventArgs<TValue>(TValue? Value);