Initial support for collapsing in clone dialog.

Makes groups in the clone dialog collapsible. If there is only a single
group, then it will be expanded; as more groups are created, the first
group is collapsed and further groups will be added collapsed.

Only problem with this is that you can see an initial flash of expanded
items when loading with multiple groups, however I felt this was
preferable to everything being collapsed until the whole list is
loaded...

Author: Steven Kirk

src/GitHub.VisualStudio/UI/Views/Controls/RepositoryCloneControl.xaml

@@ -152,25 +152,26 @@
                   <Setter Property="Template">
                     <Setter.Value>
                       <ControlTemplate TargetType="{x:Type GroupItem}">
-                        <StackPanel Orientation="Vertical"
-                                    Margin="0">
-                          <Border Background="#F8F8F8"
-                                  Style="{StaticResource repositoryBorderStyle}">
+                        <Expander IsExpanded="{Binding Name.IsExpanded}">
+                          <Expander.Header>
+                            <Border Background="#F8F8F8"
+                                    Style="{StaticResource repositoryBorderStyle}">
                             <StackPanel Orientation="Horizontal"
                                         VerticalAlignment="Center"
                                         Margin="0">
-                              <Image x:Name="avatar"
-                                     Width="16"
-                                     Height="16"
-                                     Margin="10,0,6,0"
-                                     RenderOptions.BitmapScalingMode="HighQuality"
-                                     Source="{Binding Items[0].Owner.Avatar}" />
-                              <TextBlock Text="{Binding Path=Name}"
-                                         Style="{StaticResource cloneRepoHeaderStyle}" />
+                                <Image x:Name="avatar"
+                                        Width="16"
+                                        Height="16"
+                                        Margin="10,0,6,0"
+                                        RenderOptions.BitmapScalingMode="HighQuality"
+                                        Source="{Binding Items[0].Owner.Avatar}" />
+                                <TextBlock Text="{Binding Path=Name.Header}"
+                                           Style="{StaticResource cloneRepoHeaderStyle}" />
                             </StackPanel>
-                          </Border>
+                            </Border>
+                          </Expander.Header>                        
                           <ItemsPresenter Margin="0" />
-                        </StackPanel>
+                        </Expander>
                       </ControlTemplate>
                     </Setter.Value>
                   </Setter>

src/GitHub.VisualStudio/UI/Views/Controls/RepositoryCloneControl.xaml.cs

@@ -17,6 +17,7 @@
 using ReactiveUI;
 using System.ComponentModel.Composition;
 using GitHub.Services;
+using System.Linq;
 
 namespace GitHub.VisualStudio.UI.Views.Controls
 {
@@ -30,6 +31,8 @@ public class GenericRepositoryCloneControl : SimpleViewUserControl<IRepositoryCl
     [PartCreationPolicy(CreationPolicy.NonShared)]
     public partial class RepositoryCloneControl : GenericRepositoryCloneControl
     {
+        private Dictionary<string, RepositoryGroup> groups = new Dictionary<string, RepositoryGroup>();
+
         public RepositoryCloneControl()
         {
             InitializeComponent();
@@ -60,24 +63,60 @@ public RepositoryCloneControl()
             };
         }
 
-        static ListCollectionView CreateRepositoryListCollectionView(IEnumerable<IRepositoryModel> repositories)
+        ListCollectionView CreateRepositoryListCollectionView(IEnumerable<IRepositoryModel> repositories)
         {
             var view = new ListCollectionView((IList)repositories);
             Debug.Assert(view.GroupDescriptions != null, "view.GroupDescriptions is null");
-            view.GroupDescriptions.Add(new RepositoryGroupDescription());
+            view.GroupDescriptions.Add(new RepositoryGroupDescription(this));
             return view;
         }
 
         class RepositoryGroupDescription : GroupDescription
         {
+            RepositoryCloneControl owner;
+
+            public RepositoryGroupDescription(RepositoryCloneControl owner)
+            {
+                this.owner = owner;
+            }
+
             public override object GroupNameFromItem(object item, int level, System.Globalization.CultureInfo culture)
             {
-                return ((IRepositoryModel)item).Owner.Login;
+                var name = ((IRepositoryModel)item).Owner.Login;
+                RepositoryGroup group;
+
+                if (!owner.groups.TryGetValue(name, out group))
+                {
+                    group = new RepositoryGroup(name, owner.groups.Count == 0);
+
+                    if (owner.groups.Count == 1)
+                    {
+                        owner.groups.Values.First().IsExpanded = false;
+                    }
+
+                    owner.groups.Add(name, group);
+                }
+
+                return group;
+            }
+        }
+
+        class RepositoryGroup : ReactiveObject
+        {
+            private bool isExpanded;
+
+            public RepositoryGroup(string header, bool isExpanded)
+            {
+                Header = header;
+                this.isExpanded = isExpanded;
             }
 
-            public override bool NamesMatch(object groupName, object itemName)
+            public string Header { get; }
+
+            public bool IsExpanded
             {
-                return string.Equals((string)groupName, (string)itemName);
+                get { return isExpanded; }
+                set { this.RaiseAndSetIfChanged(ref isExpanded, value); }
             }
         }
     }