Parent's children, optimalizations

src/AppCommon/FileTime.App.Core.Abstraction/Services/IRxSchedulerService.cs

@@ -0,0 +1,10 @@
+using System.Reactive.Concurrency;
+
+namespace FileTime.App.Core.Services
+{
+    public interface IRxSchedulerService
+    {
+        IScheduler GetWorkerScheduler();
+        IScheduler GetUIScheduler();
+    }
+}

src/AppCommon/FileTime.App.Core.Abstraction/ViewModels/ITabViewModel.cs

@@ -15,5 +15,6 @@ namespace FileTime.App.Core.ViewModels
         IObservable<IReadOnlyList<IItemViewModel>> CurrentItems { get; }
         IObservable<IEnumerable<FullName>> MarkedItems { get; }
         IObservable<IReadOnlyList<IItemViewModel>?> SelectedsChildren { get; }
+        IObservable<IReadOnlyList<IItemViewModel>?> ParentsChildren { get; }
     }
 }

src/AppCommon/FileTime.App.Core/ViewModels/TabViewModel.cs

@@ -1,9 +1,8 @@
+using System.Reactive.Concurrency;
 using System.Reactive.Linq;
 using System.Reactive.Subjects;
 using FileTime.App.Core.Extensions;
-using FileTime.App.Core.Models.Enums;
 using FileTime.App.Core.Services;
-using FileTime.Core.Enums;
 using FileTime.Core.Models;
 using FileTime.Core.Services;
 using Microsoft.Extensions.DependencyInjection;
@@ -15,6 +14,7 @@ namespace FileTime.App.Core.ViewModels
         private readonly IServiceProvider _serviceProvider;
         private readonly IItemNameConverterService _itemNameConverterService;
         private readonly IAppState _appState;
+        private readonly IRxSchedulerService _rxSchedulerService;
         private readonly BehaviorSubject<IEnumerable<FullName>> _markedItems = new(Enumerable.Empty<FullName>());
         private readonly List<IDisposable> _disposables = new();
         private bool disposed;
@@ -29,11 +29,13 @@ namespace FileTime.App.Core.ViewModels
         public IObservable<IReadOnlyList<IItemViewModel>> CurrentItems { get; private set; } = null!;
         public IObservable<IEnumerable<FullName>> MarkedItems { get; }
         public IObservable<IReadOnlyList<IItemViewModel>?> SelectedsChildren { get; private set; } = null!;
+        public IObservable<IReadOnlyList<IItemViewModel>?> ParentsChildren { get; private set; } = null!;
 
         public TabViewModel(
             IServiceProvider serviceProvider,
             IItemNameConverterService itemNameConverterService,
-            IAppState appState)
+            IAppState appState,
+            IRxSchedulerService rxSchedulerService)
         {
             _serviceProvider = serviceProvider;
             _itemNameConverterService = itemNameConverterService;
@@ -41,6 +43,7 @@ namespace FileTime.App.Core.ViewModels
 
             MarkedItems = _markedItems.Select(e => e.ToList()).AsObservable();
             IsSelected = _appState.SelectedTab.Select(s => s == this);
+            _rxSchedulerService = rxSchedulerService;
         }
 
         public void Init(ITab tab, int tabNumber)
@@ -49,7 +52,16 @@ namespace FileTime.App.Core.ViewModels
             TabNumber = tabNumber;
 
             CurrentLocation = tab.CurrentLocation.AsObservable();
-            CurrentItems = tab.CurrentItems.Select(items => items.Select(MapItemToViewModel).ToList()).Publish(new List<IItemViewModel>()).RefCount();
+            CurrentItems = tab.CurrentItems
+                .Select(items =>
+                    items == null
+                    ? new List<IItemViewModel>()
+                    : items.Select(MapItemToViewModel).ToList())
+                .ObserveOn(_rxSchedulerService.GetWorkerScheduler())
+                .SubscribeOn(_rxSchedulerService.GetUIScheduler())
+                .Publish(new List<IItemViewModel>())
+                .RefCount();
+
             CurrentSelectedItem =
                 Observable.CombineLatest(
                     CurrentItems,
@@ -73,7 +85,36 @@ namespace FileTime.App.Core.ViewModels
                 currentSelectedItemThrottled
                     .Where(c => c is null || c is not IContainerViewModel)
                     .Select(_ => (IReadOnlyList<IItemViewModel>?)null)
-            );
+            )
+            .ObserveOn(_rxSchedulerService.GetWorkerScheduler())
+            .SubscribeOn(_rxSchedulerService.GetUIScheduler())
+            .Publish(null)
+            .RefCount();
+
+            var parentThrottled = CurrentLocation
+                .Select(l => l?.Parent)
+                .DistinctUntilChanged()
+                .Publish(null)
+                .RefCount();
+
+            ParentsChildren = Observable.Merge(
+                parentThrottled
+                    .Where(p => p is not null)
+                    .Select(p => Observable.FromAsync(async () => (IContainer)await p!.ResolveAsync()))
+                    .Switch()
+                    .Select(p => p.Items)
+                    .Switch()
+                    .Select(items => Observable.FromAsync(async () => await Map(items)))
+                    .Switch()
+                    .Select(items => items?.Select(MapItemToViewModel).ToList()),
+                parentThrottled
+                    .Where(p => p is null)
+                    .Select(_ => (IReadOnlyList<IItemViewModel>?)null)
+            )
+            .ObserveOn(_rxSchedulerService.GetWorkerScheduler())
+            .SubscribeOn(_rxSchedulerService.GetUIScheduler())
+            .Publish(null)
+            .RefCount();
 
             tab.CurrentLocation.Subscribe((_) => _markedItems.OnNext(Enumerable.Empty<FullName>()));
 
@@ -83,7 +124,7 @@ namespace FileTime.App.Core.ViewModels
 
                 return await items
                     .ToAsyncEnumerable()
-                    .SelectAwait(async i => await i.ResolveAsync(true))
+                    .SelectAwait(async i => await i.ResolveAsync(forceResolve: true, itemInitializationSettings: new ItemInitializationSettings(true)))
                     .ToListAsync();
             }
         }

src/Core/FileTime.Core.Abstraction/Models/IAbsolutePath.cs

@@ -10,7 +10,7 @@ namespace FileTime.Core.Models
         FullName Path { get; }
         AbsolutePathType Type { get; }
 
-        Task<IItem> ResolveAsync(bool forceResolve = false);
+        Task<IItem> ResolveAsync(bool forceResolve = false, ItemInitializationSettings itemInitializationSettings = default);
-        Task<IItem?> ResolveAsyncSafe(bool forceResolve = false);
+        Task<IItem?> ResolveAsyncSafe(bool forceResolve = false, ItemInitializationSettings itemInitializationSettings = default);
     }
 }

src/Core/FileTime.Core.Abstraction/Models/ItemInitializationSettings.cs

@@ -0,0 +1,12 @@
+namespace FileTime.Core.Models
+{
+    public readonly struct ItemInitializationSettings
+    {
+        public readonly bool SkipChildInitialization;
+
+        public ItemInitializationSettings(bool skipChildInitialization)
+        {
+            SkipChildInitialization = skipChildInitialization;
+        }
+    }
+}

src/Core/FileTime.Core.Abstraction/Services/IContentProvider.cs

@@ -6,8 +6,18 @@ namespace FileTime.Core.Services
 {
     public interface IContentProvider : IContainer, IOnContainerEnter
     {
-        Task<IItem> GetItemByFullNameAsync(FullName fullName, bool forceResolve = false, AbsolutePathType forceResolvePathType = AbsolutePathType.Unknown);
+        Task<IItem> GetItemByFullNameAsync(
-        Task<IItem> GetItemByNativePathAsync(NativePath nativePath, bool forceResolve = false, AbsolutePathType forceResolvePathType = AbsolutePathType.Unknown);
+            FullName fullName,
+            bool forceResolve = false,
+            AbsolutePathType forceResolvePathType = AbsolutePathType.Unknown,
+            ItemInitializationSettings itemInitializationSettings = default);
+
+        Task<IItem> GetItemByNativePathAsync(
+            NativePath nativePath,
+            bool forceResolve = false,
+            AbsolutePathType forceResolvePathType = AbsolutePathType.Unknown,
+            ItemInitializationSettings itemInitializationSettings = default);
+
         Task<List<IAbsolutePath>> GetItemsByContainerAsync(FullName fullName);
     }
 }

src/Core/FileTime.Core.Models/AbsolutePath.cs

@@ -19,17 +19,17 @@ namespace FileTime.Core.Models
             Type = type;
         }
 
-        public async Task<IItem> ResolveAsync(bool forceResolve = false)
+        public async Task<IItem> ResolveAsync(bool forceResolve = false, ItemInitializationSettings itemInitializationSettings = default)
         {
             var provider = VirtualContentProvider ?? ContentProvider;
-            return await provider.GetItemByFullNameAsync(Path, forceResolve, Type);
+            return await provider.GetItemByFullNameAsync(Path, forceResolve, Type, itemInitializationSettings);
         }
 
-        public async Task<IItem?> ResolveAsyncSafe(bool forceResolve = false)
+        public async Task<IItem?> ResolveAsyncSafe(bool forceResolve = false, ItemInitializationSettings itemInitializationSettings = default)
         {
             try
             {
-                return await ResolveAsync(forceResolve);
+                return await ResolveAsync(forceResolve, itemInitializationSettings);
             }
             catch { return null; }
         }

src/Core/FileTime.Core.Services/ContentProviderBase.cs

@@ -49,9 +49,17 @@ namespace FileTime.Core.Services
         }
 
         public virtual Task OnEnter() => Task.CompletedTask;
-        public virtual async Task<IItem> GetItemByFullNameAsync(FullName fullName, bool forceResolve = false, AbsolutePathType forceResolvePathType = AbsolutePathType.Unknown)
+        public virtual async Task<IItem> GetItemByFullNameAsync(
-        => await GetItemByNativePathAsync(GetNativePath(fullName), forceResolve, forceResolvePathType);
+            FullName fullName,
-        public abstract Task<IItem> GetItemByNativePathAsync(NativePath nativePath, bool forceResolve = false, AbsolutePathType forceResolvePathType = AbsolutePathType.Unknown);
+            bool forceResolve = false,
+            AbsolutePathType forceResolvePathType = AbsolutePathType.Unknown,
+            ItemInitializationSettings itemInitializationSettings = default)
+        => await GetItemByNativePathAsync(GetNativePath(fullName), forceResolve, forceResolvePathType, itemInitializationSettings);
+        public abstract Task<IItem> GetItemByNativePathAsync(
+            NativePath nativePath,
+            bool forceResolve = false,
+            AbsolutePathType forceResolvePathType = AbsolutePathType.Unknown,
+            ItemInitializationSettings itemInitializationSettings = default);
         public abstract Task<List<IAbsolutePath>> GetItemsByContainerAsync(FullName fullName);
         public abstract NativePath GetNativePath(FullName fullName);
     }

src/Core/FileTime.Core.Services/Tab.cs

@@ -16,7 +16,7 @@ namespace FileTime.Core.Services
 
         public Tab()
         {
-            CurrentLocation = _currentLocation.DistinctUntilChanged().Do(_ => {; }).Publish(null).RefCount();
+            CurrentLocation = _currentLocation.DistinctUntilChanged().Publish(null).RefCount();
             CurrentItems =
                 Observable.Merge(
                     CurrentLocation
@@ -69,7 +69,7 @@ namespace FileTime.Core.Services
         private IObservable<IAbsolutePath?> GetSelectedItemByLocation(IContainer? currentLocation)
         {
             //TODO: 
-            return currentLocation?.Items?.Select(i => i.FirstOrDefault()) ?? Observable.Return((IAbsolutePath?)null);
+            return currentLocation?.Items?.Select(i => i?.FirstOrDefault()) ?? Observable.Return((IAbsolutePath?)null);
         }
 
         public void SetCurrentLocation(IContainer newLocation) => _currentLocation.OnNext(newLocation);

src/GuiApp/Avalonia/FileTime.GuiApp.App/Startup.cs

@@ -26,6 +26,7 @@ namespace FileTime.GuiApp
                 .AddSingleton<IGuiAppState, GuiAppState>(s => s.GetRequiredService<GuiAppState>())
                 .AddSingleton<DefaultModeKeyInputHandler>()
                 .AddSingleton<RapidTravelModeKeyInputHandler>()
+                .AddSingleton<IRxSchedulerService, AvaloniaRxSchedulerService>()
                 //TODO: move??
                 .AddTransient<ITab, Tab>()
                 .AddTransient<ITabViewModel, TabViewModel>()

src/GuiApp/Avalonia/FileTime.GuiApp/Services/AvaloniaRxSchedulerService.cs

@@ -0,0 +1,13 @@
+using System.Reactive.Concurrency;
+using FileTime.App.Core.Services;
+using ReactiveUI;
+
+namespace FileTime.GuiApp.Services
+{
+    public class AvaloniaRxSchedulerService : IRxSchedulerService
+    {
+        public IScheduler GetUIScheduler() => RxApp.MainThreadScheduler;
+
+        public IScheduler GetWorkerScheduler() => RxApp.TaskpoolScheduler;
+    }
+}

src/GuiApp/Avalonia/FileTime.GuiApp/Views/MainWindow.axaml

@@ -103,6 +103,23 @@
                                 <ColumnDefinition Width="45*" />
                             </Grid.ColumnDefinitions>
 
+                            <ListBox
+                                x:CompileBindings="False"
+                                AutoScrollToSelectedItem="True"
+                                Classes="ContentListView"
+                                IsTabStop="True"
+                                Items="{Binding AppState.SelectedTab^.ParentsChildren^}"
+                                ScrollViewer.HorizontalScrollBarVisibility="Hidden"
+                                ScrollViewer.VerticalScrollBarVisibility="Visible">
+                                <ListBox.ItemTemplate>
+                                    <DataTemplate x:DataType="corevm:IItemViewModel">
+                                        <local:ItemView
+                                            ShowAttributes="False"
+                                            HorizontalAlignment="Stretch"
+                                            HorizontalContentAlignment="Stretch" />
+                                    </DataTemplate>
+                                </ListBox.ItemTemplate>
+                            </ListBox>
 
                             <Rectangle
                                 Grid.Column="1"
@@ -112,7 +129,6 @@
                                 VerticalAlignment="Stretch"
                                 Fill="{DynamicResource ContentSeparatorBrush}" />
 
-
                             <Grid
                                 Grid.Column="2"
                                 RowDefinitions="Auto,*">

src/Providers/FileTime.Providers.Local/LocalContentProvider.DirectoryHelper.cs

@@ -19,17 +19,5 @@ namespace FileTime.Providers.Local
                     + ((directoryInfo.Attributes & FileAttributes.System) == FileAttributes.System ? "s" : "-");
             }
         }
-
-        private static IEnumerable<FileInfo> GetFilesSafe(DirectoryInfo directoryInfo)
-        {
-            try
-            {
-                return directoryInfo.GetFiles();
-            }
-            catch
-            {
-                return Enumerable.Empty<FileInfo>();
-            }
-        }
     }
 }

src/Providers/FileTime.Providers.Local/LocalContentProvider.cs

@@ -1,4 +1,5 @@
 using System.Reactive.Linq;
+using System.Reactive.Subjects;
 using System.Runtime.InteropServices;
 using FileTime.Core.Enums;
 using FileTime.Core.Models;
@@ -31,9 +32,14 @@ namespace FileTime.Providers.Local
             Items.OnNext(rootDirectories.Select(DirectoryToAbsolutePath).ToList());
         }
 
-        public override Task<IItem> GetItemByNativePathAsync(NativePath nativePath, bool forceResolve = false, AbsolutePathType forceResolvePathType = AbsolutePathType.Unknown)
+        public override Task<IItem> GetItemByNativePathAsync(
+            NativePath nativePath,
+            bool forceResolve = false,
+            AbsolutePathType forceResolvePathType = AbsolutePathType.Unknown,
+            ItemInitializationSettings itemInitializationSettings = default)
         {
             var path = nativePath.Path;
+            Exception? innerException;
             try
             {
                 if ((path?.Length ?? 0) == 0)
@@ -42,7 +48,7 @@ namespace FileTime.Providers.Local
                 }
                 else if (Directory.Exists(path))
                 {
-                    return Task.FromResult((IItem)DirectoryToContainer(new DirectoryInfo(path!.TrimEnd(Path.DirectorySeparatorChar) + Path.DirectorySeparatorChar)));
+                    return Task.FromResult((IItem)DirectoryToContainer(new DirectoryInfo(path!.TrimEnd(Path.DirectorySeparatorChar) + Path.DirectorySeparatorChar), !itemInitializationSettings.SkipChildInitialization));
                 }
                 else if (File.Exists(path))
                 {
@@ -56,21 +62,25 @@ namespace FileTime.Providers.Local
                     _ => "Directory or file"
                 };
 
-                if (forceResolvePathType == AbsolutePathType.Container) throw new DirectoryNotFoundException($"{type} not found: '{path}'");
+                innerException = forceResolvePathType switch
-                throw new FileNotFoundException(type + " not found", path);
+                {
+                    AbsolutePathType.Container => new DirectoryNotFoundException($"{type} not found: '{path}'"),
+                    _ => new FileNotFoundException(type + " not found", path)
+                };
             }
             catch (Exception e)
             {
                 if (!forceResolve) throw new Exception($"Could not resolve path '{nativePath.Path}' and {nameof(forceResolve)} is false.", e);
+                innerException = e;
+            }
 
             return forceResolvePathType switch
             {
-                    AbsolutePathType.Container => Task.FromResult((IItem)CreateEmptyContainer(nativePath, Observable.Return(new List<Exception>() { e }))),
+                AbsolutePathType.Container => Task.FromResult((IItem)CreateEmptyContainer(nativePath, Observable.Return(new List<Exception>() { innerException }))),
                 AbsolutePathType.Element => Task.FromResult(CreateEmptyElement(nativePath)),
-                    _ => throw new Exception($"Could not resolve path '{nativePath.Path}' and could not force create, because {nameof(forceResolvePathType)} is {nameof(AbsolutePathType.Unknown)}.", e)
+                _ => throw new Exception($"Could not resolve path '{nativePath.Path}' and could not force create, because {nameof(forceResolvePathType)} is {nameof(AbsolutePathType.Unknown)}.", innerException)
             };
         }
-        }
 
         private Container CreateEmptyContainer(NativePath nativePath, IObservable<IEnumerable<Exception>>? exceptions = null)
         {
@@ -108,8 +118,8 @@ namespace FileTime.Providers.Local
         }
 
         public override Task<List<IAbsolutePath>> GetItemsByContainerAsync(FullName fullName) => Task.FromResult(GetItemsByContainer(fullName));
-        public List<IAbsolutePath> GetItemsByContainer(FullName fullName) => GetItemsByContainer(new DirectoryInfo(GetNativePath(fullName).Path));
+        private List<IAbsolutePath> GetItemsByContainer(FullName fullName) => GetItemsByContainer(new DirectoryInfo(GetNativePath(fullName).Path));
-        public List<IAbsolutePath> GetItemsByContainer(DirectoryInfo directoryInfo) => directoryInfo.GetDirectories().Select(DirectoryToAbsolutePath).Concat(GetFilesSafe(directoryInfo).Select(FileToAbsolutePath)).ToList();
+        private List<IAbsolutePath> GetItemsByContainer(DirectoryInfo directoryInfo) => directoryInfo.GetDirectories().Select(DirectoryToAbsolutePath).Concat(directoryInfo.GetFiles().Select(FileToAbsolutePath)).ToList();
 
         private IAbsolutePath DirectoryToAbsolutePath(DirectoryInfo directoryInfo)
         {
@@ -123,7 +133,7 @@ namespace FileTime.Providers.Local
             return new AbsolutePath(this, fullName, AbsolutePathType.Element);
         }
 
-        private Container DirectoryToContainer(DirectoryInfo directoryInfo)
+        private Container DirectoryToContainer(DirectoryInfo directoryInfo, bool initializeChildren = true)
         {
             var fullName = GetFullName(directoryInfo.FullName);
             var parentFullName = fullName.GetParent();
@@ -131,6 +141,7 @@ namespace FileTime.Providers.Local
                 this,
                 parentFullName ?? new FullName(""),
                 AbsolutePathType.Container);
+            var exceptions = new BehaviorSubject<IEnumerable<Exception>>(Enumerable.Empty<Exception>());
 
             return new(
                 directoryInfo.Name,
@@ -145,9 +156,24 @@ namespace FileTime.Providers.Local
                 true,
                 GetDirectoryAttributes(directoryInfo),
                 this,
-                Observable.Return(Enumerable.Empty<Exception>()),
+                exceptions,
-                Observable.Return(GetItemsByContainer(directoryInfo))
+                Observable.FromAsync(async () => await Task.Run(InitChildren))
             );
+
+            Task<List<IAbsolutePath>?> InitChildren()
+            {
+                List<IAbsolutePath>? result = null;
+                try
+                {
+                    result = initializeChildren ? (List<IAbsolutePath>?)GetItemsByContainer(directoryInfo) : null;
+                }
+                catch (Exception e)
+                {
+                    exceptions.OnNext(new List<Exception>() { e });
+                }
+
+                return Task.FromResult(result);
+            }
         }
 
         private Element FileToElement(FileInfo fileInfo)