New WinoListView implementation with multiple selections.

Wino.Mail.ViewModels/Data/IMailListItem.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Collections.Generic;
+using System.ComponentModel;
 using Wino.Core.Domain.Interfaces;
 
 namespace Wino.Mail.ViewModels.Data;
@@ -7,7 +9,7 @@ namespace Wino.Mail.ViewModels.Data;
 /// Common interface for mail items that can be displayed in a mail list.
 /// Implemented by both MailItemViewModel and ThreadMailItemViewModel.
 /// </summary>
-public interface IMailListItem : IMailHashContainer
+public interface IMailListItem : IMailHashContainer, INotifyPropertyChanged
 {
     /// <summary>
     /// Gets the latest creation date for sorting purposes.
@@ -22,4 +24,18 @@ public interface IMailListItem : IMailHashContainer
     /// For ThreadMailItemViewModel: the latest email's from name
     /// </summary>
     string FromName { get; }
+
+    /// <summary>
+    /// Gets whether this item is selected.
+    /// For MailItemViewModel: returns IsSelected
+    /// For ThreadMailItemViewModel: returns IsSelected
+    /// </summary>
+    bool IsSelected { get; set; }
+
+    /// <summary>
+    /// Gets all selected mail items within this list item.
+    /// For MailItemViewModel: returns itself if IsSelected is true, otherwise empty
+    /// For ThreadMailItemViewModel: returns all selected emails within the thread
+    /// </summary>
+    IEnumerable<MailItemViewModel> GetSelectedMailItems();
 }

Wino.Mail.ViewModels/Data/MailItemViewModel.cs

@@ -91,4 +91,12 @@ public partial class MailItemViewModel(MailCopy mailCopy) : ObservableObject, IM
     }
 
     public IEnumerable<Guid> GetContainingIds() => [MailCopy.UniqueId];
+
+    public IEnumerable<MailItemViewModel> GetSelectedMailItems()
+    {
+        if (IsSelected)
+        {
+            yield return this;
+        }
+    }
 }

Wino.Mail.ViewModels/Data/ThreadMailItemViewModel.cs

@@ -118,4 +118,18 @@ public partial class ThreadMailItemViewModel : ObservableRecipient, IDisposable,
     public bool HasUniqueId(Guid uniqueId) => _threadEmails.Any(email => email.MailCopy.UniqueId == uniqueId);
 
     public IEnumerable<Guid> GetContainingIds() => ThreadEmails.Select(a => a.MailCopy.UniqueId);
+
+    public IEnumerable<MailItemViewModel> GetSelectedMailItems()
+    {
+        if (IsSelected)
+        {
+            // If the thread itself is selected, return all emails in the thread
+            return ThreadEmails;
+        }
+        else
+        {
+            // Otherwise, return only individually selected emails within the thread
+            return ThreadEmails.Where(e => e.IsSelected);
+        }
+    }
 }