add "Add to group" context menu action

src/KeyKeeper/ViewModels/UnlockedRepositoryViewModel.cs

@@ -126,6 +126,23 @@ public class UnlockedRepositoryViewModel : ViewModelBase
         OnPropertyChanged(nameof(Passwords));
     }
 
+    public bool AddEntryToGroup(PassStoreEntry entry, PassStoreEntryGroup targetGroup)
+    {
+        PassStoreEntryPassword? pwd = FollowLinkIfNeeded(entry);
+        if (pwd == null) return false;
+
+        foreach (var bl in pwd.Backlinks)
+        {
+            if (bl is PassStoreEntryLink lnk && lnk.Parent == targetGroup)
+                return false;
+        }
+        passStore.AddEntry(targetGroup, new PassStoreEntryLink(Guid.NewGuid(), DateTime.Now, DateTime.Now, pwd.Id, pwd));
+
+        HasUnsavedChanges = true;
+        OnPropertyChanged(nameof(Passwords));
+        return true;
+    }
+
     public void UpdateEntry(PassStoreEntryPassword updatedEntry)
     {
         passStore.UpdateEntry(null, updatedEntry.Id, updatedEntry);

src/KeyKeeper/Views/RepositoryWindow.axaml

@@ -154,10 +154,11 @@
                                     </TextBlock>
                                 </StackPanel>
                                 <Border.ContextMenu>
-                                    <ContextMenu>
+                                    <ContextMenu Opened="EntryContextMenu_Opening">
                                         <MenuItem Name="entryCtxMenuCopyUsername" Header="Copy username" Click="EntryContextMenuItem_Click"/>
                                         <MenuItem Name="entryCtxMenuCopyPassword" Header="Copy password" Click="EntryContextMenuItem_Click"/>
                                         <MenuItem Name="entryCtxMenuEdit" Header="Edit" Click="EntryContextMenuItem_Click"/>
+                                        <MenuItem Name="entryCtxMenuAddToGroup" Header="Add to group" />
                                         <MenuItem Name="entryCtxMenuDelete" Header="Delete" Click="EntryContextMenuItem_Click"/>
                                     </ContextMenu>
                                 </Border.ContextMenu>

src/KeyKeeper/Views/RepositoryWindow.axaml.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Interactivity;
@@ -14,6 +15,7 @@ public partial class RepositoryWindow : Window
 {
     private bool allowClose;
     private bool closeConfirmationShown;
+    private PassStoreEntry? _contextMenuEntry;
 
     public RepositoryWindow(RepositoryWindowViewModel model)
     {
@@ -223,6 +225,66 @@ public partial class RepositoryWindow : Window
         }
     }
 
+    private void EntryContextMenu_Opening(object? sender, RoutedEventArgs args)
+    {
+        if (sender is not ContextMenu contextMenu || DataContext is not RepositoryWindowViewModel vm ||
+            vm.CurrentPage is not UnlockedRepositoryViewModel pageVm)
+            return;
+
+        _contextMenuEntry = null;
+
+        if (contextMenu.Parent?.Parent is Border border && border.DataContext is PassStoreEntry entry)
+        {
+            _contextMenuEntry = entry;
+        }
+
+        var addToGroupItem = contextMenu.Items
+            .OfType<MenuItem>()
+            .FirstOrDefault(m => m.Name == "entryCtxMenuAddToGroup");
+
+        if (addToGroupItem == null)
+            return;
+
+        addToGroupItem.Items.Clear();
+
+        var nonDefaultGroups = pageVm.PasswordGroups
+            .Where(g => g.GroupType != FileFormatConstants.GROUP_TYPE_DEFAULT)
+            .ToList();
+
+        EventHandler<RoutedEventArgs> onSubmenuClick = (sender, args) => AddToGroup_Click(sender, args, _contextMenuEntry!);
+        foreach (var group in nonDefaultGroups)
+        {
+            var menuItem = new MenuItem
+            {
+                Header = group.DisplayName,
+                Tag = group
+            };
+            menuItem.Click += onSubmenuClick;
+            addToGroupItem.Items.Add(menuItem);
+        }
+    }
+
+    private void AddToGroup_Click(object? sender, RoutedEventArgs args, PassStoreEntry entry)
+    {
+        if (sender is not MenuItem item || item.Tag is not PassStoreEntryGroup targetGroup)
+            return;
+
+        if (entry == null)
+            return;
+
+        if (DataContext is not RepositoryWindowViewModel vm ||
+            vm.CurrentPage is not UnlockedRepositoryViewModel pageVm)
+            return;
+
+        var notificationHost = this.FindControlRecursive<ToastNotificationHost>("NotificationHost");
+
+        if (pageVm.AddEntryToGroup(entry, targetGroup))
+            notificationHost?.Show($"Added to {targetGroup.DisplayName}");
+        else
+            notificationHost?.Show($"This entry is already in {targetGroup.DisplayName}!");
+        _contextMenuEntry = null;
+    }
+
     private async void EntryContextMenuItem_Click(object sender, RoutedEventArgs args)
     {
         if (args.Source is StyledElement s && s.DataContext is PassStoreEntry ent)