From a37fc2acc1d025cf878c8e8df47f937a5464e3c5 Mon Sep 17 00:00:00 2001
From: trawzified <55751269+tr4wzified@users.noreply.github.com>
Date: Sat, 25 May 2024 22:57:00 +0200
Subject: [PATCH] Load folder contents on expand instead of initially for much
 increased performance

---
 .../Compiler/CompilerFileManagerVM.cs         | 22 ++++++++++++++-----
 .../Compiler/CompilerFileManagerView.xaml.cs  |  2 ++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/Wabbajack.App.Wpf/ViewModels/Compiler/CompilerFileManagerVM.cs b/Wabbajack.App.Wpf/ViewModels/Compiler/CompilerFileManagerVM.cs
index 917b16a4..ef772618 100644
--- a/Wabbajack.App.Wpf/ViewModels/Compiler/CompilerFileManagerVM.cs
+++ b/Wabbajack.App.Wpf/ViewModels/Compiler/CompilerFileManagerVM.cs
@@ -69,33 +69,45 @@ namespace Wabbajack
             this.WhenActivated(disposables =>
             {
                 var fileTree = GetDirectoryContents(new DirectoryInfo(Settings.Source.ToString()));
-                Files = LoadFileTree(new DirectoryInfo(Settings.Source.ToString()));
+                Files = LoadFiles(new DirectoryInfo(Settings.Source.ToString()));
                 Disposable.Create(() => { }).DisposeWith(disposables);
             });
         }
 
-        private IEnumerable<TreeViewItem> LoadFileTree(DirectoryInfo parent)
+        private IEnumerable<TreeViewItem> LoadFiles(DirectoryInfo parent)
         {
             var parentTreeItem = new TreeViewItem()
             {
                 Header = parent,
                 IsExpanded = true,
-                ItemsSource = GetRecursiveFileTree(parent)
+                ItemsSource = LoadDirectoryContents(parent)
             };
             return [parentTreeItem];
 
         }
 
-        private IEnumerable<TreeViewItem> GetRecursiveFileTree(DirectoryInfo parent)
+        private IEnumerable<TreeViewItem> LoadDirectoryContents(DirectoryInfo parent)
         {
             return parent.EnumerateDirectories()
                   .OrderBy(dir => dir.Name)
-                  .Select(dir => new TreeViewItem() { Header = dir, ItemsSource = GetRecursiveFileTree(dir) })
+                  .Select(dir => new TreeViewItem() { Header = dir, ItemsSource = (dir.EnumerateDirectories().Any() || dir.EnumerateFiles().Any()) ? new ObservableCollection<TreeViewItem>([new TreeViewItem() { Header = "Loading..." }]) : null}).Select(item => {
+                      item.Expanded += LoadingItem_Expanded;
+                      return item;
+                  })
                   .Concat(parent.EnumerateFiles()
                                 .OrderBy(file => file.Name)
                                 .Select(file => new TreeViewItem() { Header = file }));
         }
 
+        private void LoadingItem_Expanded(object sender, System.Windows.RoutedEventArgs e)
+        {
+            var parent = (TreeViewItem)e.OriginalSource;
+            var children = parent.ItemsSource.OfType<TreeViewItem>();
+            var firstChild = children.Any() ? children.First().Header : null;
+            if (firstChild != null && firstChild is string firstString && firstString == "Loading...")
+                parent.ItemsSource = LoadDirectoryContents((DirectoryInfo)parent.Header);
+        }
+
         private IEnumerable<FileSystemInfo> GetDirectoryContents(DirectoryInfo dir)
         {
             var directories = dir.EnumerateDirectories();
diff --git a/Wabbajack.App.Wpf/Views/Compiler/CompilerFileManagerView.xaml.cs b/Wabbajack.App.Wpf/Views/Compiler/CompilerFileManagerView.xaml.cs
index 20714527..09706927 100644
--- a/Wabbajack.App.Wpf/Views/Compiler/CompilerFileManagerView.xaml.cs
+++ b/Wabbajack.App.Wpf/Views/Compiler/CompilerFileManagerView.xaml.cs
@@ -15,6 +15,7 @@ using Wabbajack.Paths;
 using Wabbajack.Paths.IO;
 using Wabbajack.ViewModels.Controls;
 using Wabbajack.Services.OSIntegrated;
+using ReactiveMarbles.ObservableEvents;
 
 namespace Wabbajack
 {
@@ -33,6 +34,7 @@ namespace Wabbajack
                 this.WhenAny(x => x.ViewModel.Files)
                     .BindToStrict(this, v => v.FileTreeView.ItemsSource)
                     .DisposeWith(disposables);
+
             });
 
         }