// Copyright (c) 2011 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

#nullable enable

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Reflection.Metadata;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Threading;
using System.Xml;

using ICSharpCode.AvalonEdit;
using ICSharpCode.AvalonEdit.Document;
using ICSharpCode.AvalonEdit.Editing;
using ICSharpCode.AvalonEdit.Folding;
using ICSharpCode.AvalonEdit.Highlighting;
using ICSharpCode.AvalonEdit.Highlighting.Xshd;
using ICSharpCode.AvalonEdit.Rendering;
using ICSharpCode.AvalonEdit.Search;
using ICSharpCode.Decompiler;
using ICSharpCode.Decompiler.CSharp.OutputVisitor;
using ICSharpCode.Decompiler.CSharp.ProjectDecompiler;
using ICSharpCode.Decompiler.Documentation;
using ICSharpCode.Decompiler.TypeSystem;
using ICSharpCode.ILSpy.AssemblyTree;
using ICSharpCode.ILSpy.AvalonEdit;
using ICSharpCode.ILSpy.Options;
using ICSharpCode.ILSpy.Themes;
using ICSharpCode.ILSpy.TreeNodes;
using ICSharpCode.ILSpy.ViewModels;
using ICSharpCode.ILSpyX;

using Microsoft.Win32;

using TomsToolbox.Composition;
using TomsToolbox.Wpf;

using ResourceKeys = ICSharpCode.ILSpy.Themes.ResourceKeys;

namespace ICSharpCode.ILSpy.TextView
{
	/// <summary>
	/// Manages the TextEditor showing the decompiled code.
	/// Contains all the threading logic that makes the decompiler work in the background.
	/// </summary>
	public sealed partial class DecompilerTextView : UserControl, IHaveState, IProgress<DecompilationProgress>
	{
		readonly IExportProvider exportProvider;
		readonly SettingsService settingsService;
		readonly LanguageService languageService;
		readonly MainWindow mainWindow;
		readonly ReferenceElementGenerator referenceElementGenerator;
		readonly UIElementGenerator uiElementGenerator;
		readonly List<VisualLineElementGenerator?> activeCustomElementGenerators = new List<VisualLineElementGenerator?>();
		readonly BracketHighlightRenderer bracketHighlightRenderer;
		RichTextColorizer? activeRichTextColorizer;
		RichTextModel? activeRichTextModel;
		FoldingManager? foldingManager;
		ILSpyTreeNode[]? decompiledNodes;
		Uri? currentAddress;
		string? currentTitle;
		bool expandMemberDefinitions;

		DefinitionLookup? definitionLookup;
		TextSegmentCollection<ReferenceSegment>? references;
		CancellationTokenSource? currentCancellationTokenSource;

		readonly TextMarkerService textMarkerService;
		readonly List<ITextMarker> localReferenceMarks = new List<ITextMarker>();

		#region Constructor
		public DecompilerTextView(IExportProvider exportProvider)
		{
			this.exportProvider = exportProvider;
			settingsService = exportProvider.GetExportedValue<SettingsService>();
			languageService = exportProvider.GetExportedValue<LanguageService>();
			mainWindow = exportProvider.GetExportedValue<MainWindow>();

			RegisterHighlighting();

			InitializeComponent();

			this.referenceElementGenerator = new ReferenceElementGenerator(this.IsLink);
			textEditor.TextArea.TextView.ElementGenerators.Add(referenceElementGenerator);
			this.uiElementGenerator = new UIElementGenerator();
			this.bracketHighlightRenderer = new BracketHighlightRenderer(textEditor.TextArea.TextView);
			textEditor.TextArea.TextView.ElementGenerators.Add(uiElementGenerator);
			textEditor.Options.RequireControlModifierForHyperlinkClick = false;
			textEditor.TextArea.TextView.MouseHover += TextViewMouseHover;
			textEditor.TextArea.TextView.MouseHoverStopped += TextViewMouseHoverStopped;
			textEditor.TextArea.PreviewMouseDown += TextAreaMouseDown;
			textEditor.TextArea.PreviewMouseUp += TextAreaMouseUp;
			textEditor.TextArea.Caret.PositionChanged += HighlightBrackets;
			textEditor.MouseMove += TextEditorMouseMove;
			textEditor.MouseLeave += TextEditorMouseLeave;
			textEditor.SetBinding(Control.FontFamilyProperty, new Binding { Source = settingsService.DisplaySettings, Path = new PropertyPath("SelectedFont") });
			textEditor.SetBinding(Control.FontSizeProperty, new Binding { Source = settingsService.DisplaySettings, Path = new PropertyPath("SelectedFontSize") });
			textEditor.SetBinding(TextEditor.WordWrapProperty, new Binding { Source = settingsService.DisplaySettings, Path = new PropertyPath("EnableWordWrap") });

			// disable Tab editing command (useless for read-only editor); allow using tab for focus navigation instead
			RemoveEditCommand(EditingCommands.TabForward);
			RemoveEditCommand(EditingCommands.TabBackward);

			textMarkerService = new TextMarkerService(textEditor.TextArea.TextView);
			textEditor.TextArea.TextView.BackgroundRenderers.Add(textMarkerService);
			textEditor.TextArea.TextView.LineTransformers.Add(textMarkerService);
			textEditor.ShowLineNumbers = true;

			MessageBus<SettingsChangedEventArgs>.Subscribers += Settings_Changed;

			// SearchPanel
			SearchPanel searchPanel = SearchPanel.Install(textEditor.TextArea);
			searchPanel.RegisterCommands(mainWindow.CommandBindings);
			searchPanel.SetResourceReference(SearchPanel.MarkerBrushProperty, ResourceKeys.SearchResultBackgroundBrush);
			searchPanel.Loaded += (_, _) => {
				// HACK: fix search text box
				var textBox = searchPanel.Template.FindName("PART_searchTextBox", searchPanel) as TextBox;
				if (textBox != null)
				{
					// the hardcoded but misaligned margin
					textBox.Margin = new Thickness(3);
					// the hardcoded height
					textBox.Height = double.NaN;
				}
			};

			ShowLineMargin();
			SetHighlightCurrentLine();

			ContextMenuProvider.Add(this);

			textEditor.TextArea.TextView.SetResourceReference(ICSharpCode.AvalonEdit.Rendering.TextView.LinkTextForegroundBrushProperty, ResourceKeys.LinkTextForegroundBrush);
			textEditor.TextArea.TextView.SetResourceReference(ICSharpCode.AvalonEdit.Rendering.TextView.CurrentLineBackgroundProperty, ResourceKeys.CurrentLineBackgroundBrush);
			textEditor.TextArea.TextView.SetResourceReference(ICSharpCode.AvalonEdit.Rendering.TextView.CurrentLineBorderProperty, ResourceKeys.CurrentLineBorderPen);

			DataObject.AddSettingDataHandler(textEditor.TextArea, OnSettingData);

			this.DataContextChanged += DecompilerTextView_DataContextChanged;
		}

		private void DecompilerTextView_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
		{
			if (this.DataContext is PaneModel model)
			{
				model.Title = currentTitle ?? ILSpy.Properties.Resources.Decompiling;
			}
		}

		void RemoveEditCommand(RoutedUICommand command)
		{
			var handler = textEditor.TextArea.DefaultInputHandler.Editing;
			var inputBinding = handler.InputBindings.FirstOrDefault(b => b.Command == command);
			if (inputBinding != null)
				handler.InputBindings.Remove(inputBinding);
			var commandBinding = handler.CommandBindings.FirstOrDefault(b => b.Command == command);
			if (commandBinding != null)
				handler.CommandBindings.Remove(commandBinding);
		}
		#endregion

		#region Line margin

		private void Settings_Changed(object? sender, SettingsChangedEventArgs e)
		{
			Settings_PropertyChanged(sender, e);
		}

		private void Settings_PropertyChanged(object? sender, PropertyChangedEventArgs e)
		{
			if (sender is not DisplaySettings)
				return;

			switch (e.PropertyName)
			{
				case nameof(DisplaySettings.ShowLineNumbers):
					ShowLineMargin();
					break;
				case nameof(DisplaySettings.HighlightCurrentLine):
					SetHighlightCurrentLine();
					break;
			}
		}

		void ShowLineMargin()
		{
			foreach (var margin in this.textEditor.TextArea.LeftMargins)
			{
				if (margin is LineNumberMargin || margin is System.Windows.Shapes.Line)
				{
					margin.Visibility = settingsService.DisplaySettings.ShowLineNumbers ? Visibility.Visible : Visibility.Collapsed;
				}
			}
		}

		void SetHighlightCurrentLine()
		{
			textEditor.Options.HighlightCurrentLine = settingsService.DisplaySettings.HighlightCurrentLine;
		}

		#endregion

		#region Tooltip support
		ToolTip? toolTip;
		Popup? popupToolTip;

		void TextViewMouseHover(object sender, MouseEventArgs e)
		{
			if (!TryCloseExistingPopup(false))
			{
				return;
			}
			TextViewPosition? position = GetPositionFromMousePosition();
			if (position == null)
				return;
			int offset = textEditor.Document.GetOffset(position.Value.Location);
			if (referenceElementGenerator.References == null)
				return;
			ReferenceSegment? seg = referenceElementGenerator.References.FindSegmentsContaining(offset).FirstOrDefault();
			if (seg == null)
				return;
			object? content = GenerateTooltip(seg);

			if (content != null)
			{
				popupToolTip = content as Popup;

				if (popupToolTip != null)
				{
					var popupPosition = GetPopupPosition(e);
					popupToolTip.Closed += ToolTipClosed;
					popupToolTip.Placement = PlacementMode.Relative;
					popupToolTip.PlacementTarget = this;
					popupToolTip.HorizontalOffset = popupPosition.X;
					popupToolTip.VerticalOffset = popupPosition.Y;
					popupToolTip.StaysOpen = true;  // We will close it ourselves

					e.Handled = true;
					popupToolTip.IsOpen = true;
					distanceToPopupLimit = double.PositiveInfinity; // reset limit; we'll re-calculate it on the next mouse movement
				}
				else
				{
					if (toolTip == null)
					{
						toolTip = new ToolTip();
						toolTip.Closed += ToolTipClosed;
					}
					toolTip.PlacementTarget = this; // required for property inheritance

					if (content is string s)
					{
						toolTip.Content = new TextBlock {
							Text = s,
							TextWrapping = TextWrapping.Wrap
						};
					}
					else
						toolTip.Content = content;

					e.Handled = true;
					toolTip.IsOpen = true;
				}
			}
		}

		bool TryCloseExistingPopup(bool mouseClick)
		{
			if (popupToolTip != null)
			{
				if (popupToolTip.IsOpen && !mouseClick && popupToolTip is FlowDocumentTooltip t && !t.CloseWhenMouseMovesAway)
				{
					return false; // Popup does not want to be closed yet
				}
				popupToolTip.IsOpen = false;
				popupToolTip = null;
			}
			return true;
		}

		/// <summary> Returns Popup position based on mouse position, in device independent units </summary>
		Point GetPopupPosition(MouseEventArgs mouseArgs)
		{
			Point mousePos = mouseArgs.GetPosition(this);
			// align Popup with line bottom
			TextViewPosition? logicalPos = textEditor.GetPositionFromPoint(mousePos);
			if (logicalPos.HasValue)
			{
				var textView = textEditor.TextArea.TextView;
				return textView.GetVisualPosition(logicalPos.Value, VisualYPosition.LineBottom)
					- textView.ScrollOffset
					+ new Vector(-4, 0);
			}
			else
			{
				return mousePos + new Vector(-4, 6);
			}
		}

		void TextViewMouseHoverStopped(object sender, MouseEventArgs e)
		{
			// Non-popup tooltips get closed as soon as the mouse starts moving again
			if (toolTip != null)
			{
				toolTip.IsOpen = false;
				e.Handled = true;
			}
		}

		double distanceToPopupLimit;
		const double MaxMovementAwayFromPopup = 5;

		void TextEditorMouseMove(object sender, MouseEventArgs e)
		{
			if (popupToolTip != null && PresentationSource.FromVisual(popupToolTip.Child) != null)
			{
				double distanceToPopup = GetDistanceToPopup(e);
				if (distanceToPopup > distanceToPopupLimit)
				{
					// Close popup if mouse moved away, exceeding the limit
					TryCloseExistingPopup(false);
				}
				else
				{
					// reduce distanceToPopupLimit
					distanceToPopupLimit = Math.Min(distanceToPopupLimit, distanceToPopup + MaxMovementAwayFromPopup);
				}
			}
		}

		double GetDistanceToPopup(MouseEventArgs e)
		{
			Point p = popupToolTip!.Child.PointFromScreen(PointToScreen(e.GetPosition(this)));
			Size size = popupToolTip.Child.RenderSize;
			double x = 0;
			if (p.X < 0)
				x = -p.X;
			else if (p.X > size.Width)
				x = p.X - size.Width;
			double y = 0;
			if (p.Y < 0)
				y = -p.Y;
			else if (p.Y > size.Height)
				y = p.Y - size.Height;
			return Math.Sqrt(x * x + y * y);
		}

		void TextEditorMouseLeave(object sender, MouseEventArgs e)
		{
			if (popupToolTip != null && !popupToolTip.IsMouseOver)
			{
				// do not close popup if mouse moved from editor to popup
				TryCloseExistingPopup(false);
			}
		}

		void OnUnloaded(object sender, EventArgs e)
		{
			// Close popup when another document gets selected
			// TextEditorMouseLeave is not sufficient for this because the mouse might be over the popup when the document switch happens (e.g. Ctrl+Tab)
			TryCloseExistingPopup(true);
		}

		void ToolTipClosed(object? sender, EventArgs e)
		{
			if (toolTip == sender)
			{
				toolTip = null;
			}
			if (popupToolTip == sender)
			{
				// Because popupToolTip instances are created by the tooltip provider,
				// they might be reused; so we should detach the event handler
				if (popupToolTip != null)
				{
					popupToolTip.Closed -= ToolTipClosed;
				}
				popupToolTip = null;
			}
		}

		object? GenerateTooltip(ReferenceSegment segment)
		{
			var fontSize = settingsService.DisplaySettings.SelectedFontSize;

			if (segment.Reference is ICSharpCode.Decompiler.Disassembler.OpCodeInfo code)
			{
				XmlDocumentationProvider docProvider = XmlDocLoader.MscorlibDocumentation;
				DocumentationUIBuilder renderer = new DocumentationUIBuilder(new CSharpAmbience(), languageService.Language.SyntaxHighlighting, settingsService.DisplaySettings, mainWindow);
				renderer.AddSignatureBlock($"{code.Name} (0x{code.Code:x})");
				if (docProvider != null)
				{
					string documentation = docProvider.GetDocumentation("F:System.Reflection.Emit.OpCodes." + code.EncodedName);
					if (documentation != null)
					{
						renderer.AddXmlDocumentation(documentation, null, null);
					}
				}
				return new FlowDocumentTooltip(renderer.CreateDocument(), fontSize, mainWindow.ActualWidth);
			}
			else if (segment.Reference is IEntity entity)
			{
				var document = CreateTooltipForEntity(entity);
				if (document == null)
					return null;
				return new FlowDocumentTooltip(document, fontSize, mainWindow.ActualWidth);
			}
			else if (segment.Reference is EntityReference unresolvedEntity)
			{
				var assemblyList = exportProvider.GetExportedValue<AssemblyList>();
				var module = unresolvedEntity.ResolveAssembly(assemblyList);
				if (module == null)
					return null;
				var typeSystem = new DecompilerTypeSystem(module,
					module.GetAssemblyResolver(),
					TypeSystemOptions.Default | TypeSystemOptions.Uncached);
				try
				{
					Handle handle = unresolvedEntity.Handle;
					if (!handle.IsEntityHandle())
						return null;
					IEntity resolved = typeSystem.MainModule.ResolveEntity((EntityHandle)handle);
					if (resolved == null)
						return null;
					var document = CreateTooltipForEntity(resolved);
					if (document == null)
						return null;
					return new FlowDocumentTooltip(document, fontSize, mainWindow.ActualWidth);
				}
				catch (BadImageFormatException)
				{
					return null;
				}
			}
			return null;
		}

		FlowDocument? CreateTooltipForEntity(IEntity resolved)
		{
			Language currentLanguage = languageService.Language;
			DocumentationUIBuilder renderer = new DocumentationUIBuilder(new CSharpAmbience(), currentLanguage.SyntaxHighlighting, settingsService.DisplaySettings, mainWindow);
			RichText richText = currentLanguage.GetRichTextTooltip(resolved);
			if (richText == null)
			{
				return null;
			}

			renderer.AddSignatureBlock(richText.Text, richText.ToRichTextModel());
			try
			{
				if (resolved.ParentModule == null || resolved.ParentModule.MetadataFile == null)
					return null;
				var docProvider = XmlDocLoader.LoadDocumentation(resolved.ParentModule.MetadataFile);
				if (docProvider != null)
				{
					string documentation = docProvider.GetDocumentation(resolved.GetIdString());
					if (documentation != null)
					{
						renderer.AddXmlDocumentation(documentation, resolved, ResolveReference);
					}
				}
			}
			catch (XmlException)
			{
				// ignore
			}
			return renderer.CreateDocument();

			IEntity? ResolveReference(string idString)
			{
				var assemblyList = exportProvider.GetExportedValue<AssemblyList>();
				return AssemblyTreeModel.FindEntityInRelevantAssemblies(idString, assemblyList.GetAssemblies());
			}
		}

		sealed class FlowDocumentTooltip : Popup
		{
			readonly FlowDocumentScrollViewer viewer;

			public FlowDocumentTooltip(FlowDocument document, double fontSize, double maxWith)
			{
				TextOptions.SetTextFormattingMode(this, TextFormattingMode.Display);
				viewer = new() {
					Width = document.MinPageWidth + fontSize * 5,
					MaxWidth = maxWith,
					Document = document
				};
				Border border = new Border {
					BorderThickness = new Thickness(1),
					MaxHeight = 400,
					Child = viewer
				};
				border.SetResourceReference(Border.BackgroundProperty, SystemColors.ControlBrushKey);
				border.SetResourceReference(Border.BorderBrushProperty, SystemColors.ControlDarkBrushKey);

				this.Child = border;
				viewer.SetResourceReference(ForegroundProperty, SystemColors.InfoTextBrushKey);
				document.TextAlignment = TextAlignment.Left;
				document.FontSize = fontSize;
				document.FontFamily = SystemFonts.SmallCaptionFontFamily;
			}

			public bool CloseWhenMouseMovesAway {
				get { return !this.IsKeyboardFocusWithin; }
			}

			protected override void OnLostKeyboardFocus(KeyboardFocusChangedEventArgs e)
			{
				base.OnLostKeyboardFocus(e);
				this.IsOpen = false;
			}

			protected override void OnMouseLeave(MouseEventArgs e)
			{
				base.OnMouseLeave(e);
				// When the mouse is over the popup, it is possible for ILSpy to be minimized,
				// or moved into the background, and yet the popup stays open.
				// We don't have a good method here to check whether the mouse moved back into the text area
				// or somewhere else, so we'll just close the popup.
				if (CloseWhenMouseMovesAway)
					this.IsOpen = false;
			}
		}
		#endregion

		#region Highlight brackets
		void HighlightBrackets(object? sender, EventArgs e)
		{
			if (settingsService.DisplaySettings.HighlightMatchingBraces)
			{
				var result = languageService.Language.BracketSearcher.SearchBracket(textEditor.Document, textEditor.CaretOffset);
				bracketHighlightRenderer.SetHighlight(result);
			}
			else
			{
				bracketHighlightRenderer.SetHighlight(null);
			}
		}
		#endregion

		#region RunWithCancellation
		public void Report(DecompilationProgress value)
		{
			double v = (double)value.UnitsCompleted / value.TotalUnits;
			Dispatcher.BeginInvoke(DispatcherPriority.Normal, delegate {
				progressBar.IsIndeterminate = !double.IsFinite(v);
				progressBar.Value = v * 100.0;
				progressTitle.Text = !string.IsNullOrWhiteSpace(value.Title) ? value.Title : Properties.Resources.Decompiling;
				progressText.Text = value.Status;
				progressText.Visibility = !string.IsNullOrWhiteSpace(progressText.Text) ? Visibility.Visible : Visibility.Collapsed;
				var taskBar = mainWindow.TaskbarItemInfo;
				if (taskBar != null)
				{
					taskBar.ProgressState = System.Windows.Shell.TaskbarItemProgressState.Normal;
					taskBar.ProgressValue = v;
				}
				if (this.DataContext is TabPageModel model)
				{
					model.Title = progressTitle.Text;
				}
			});
		}

		/// <summary>
		/// Switches the GUI into "waiting" mode, then calls <paramref name="taskCreation"/> to create
		/// the task.
		/// If another task is started before the previous task finishes running, the previous task is cancelled.
		/// </summary>
		public Task<T> RunWithCancellation<T>(Func<CancellationToken, Task<T>> taskCreation, string? progressTitle = null)
		{
			if (waitAdorner.Visibility != Visibility.Visible)
			{
				waitAdorner.Visibility = Visibility.Visible;
				// Work around a WPF bug by setting IsIndeterminate only while the progress bar is visible.
				// https://github.com/icsharpcode/ILSpy/issues/593
				this.progressTitle.Text = progressTitle == null ? Properties.Resources.Decompiling : progressTitle;
				progressBar.IsIndeterminate = true;
				progressText.Text = null;
				progressText.Visibility = Visibility.Collapsed;
				waitAdorner.BeginAnimation(OpacityProperty, new DoubleAnimation(0, 1, new Duration(TimeSpan.FromSeconds(0.5)), FillBehavior.Stop));
				var taskBar = mainWindow.TaskbarItemInfo;
				if (taskBar != null)
				{
					taskBar.ProgressState = System.Windows.Shell.TaskbarItemProgressState.Indeterminate;
				}
			}
			CancellationTokenSource? previousCancellationTokenSource = currentCancellationTokenSource;
			var myCancellationTokenSource = new CancellationTokenSource();
			currentCancellationTokenSource = myCancellationTokenSource;
			// cancel the previous only after current was set to the new one (avoid that the old one still finishes successfully)
			if (previousCancellationTokenSource != null)
			{
				previousCancellationTokenSource.Cancel();
			}

			var tcs = new TaskCompletionSource<T>();
			Task<T> task;
			try
			{
				task = taskCreation(myCancellationTokenSource.Token);
			}
			catch (OperationCanceledException)
			{
				task = TaskHelper.FromCancellation<T>();
			}
			catch (Exception ex)
			{
				task = TaskHelper.FromException<T>(ex);
			}
			Action continuation = delegate {
				try
				{
					if (currentCancellationTokenSource == myCancellationTokenSource)
					{
						currentCancellationTokenSource = null;
						waitAdorner.Visibility = Visibility.Collapsed;
						progressBar.IsIndeterminate = false;
						progressText.Text = null;
						progressText.Visibility = Visibility.Collapsed;
						var taskBar = mainWindow.TaskbarItemInfo;
						if (taskBar != null)
						{
							taskBar.ProgressState = System.Windows.Shell.TaskbarItemProgressState.None;
						}
						if (task.IsCanceled)
						{
							AvalonEditTextOutput output = new AvalonEditTextOutput();
							output.WriteLine("The operation was canceled.");
							ShowOutput(output);
						}
						tcs.SetFromTask(task);
					}
					else
					{
						tcs.SetCanceled();
					}
				}
				finally
				{
					myCancellationTokenSource.Dispose();
				}
			};
			task.ContinueWith(delegate { Dispatcher.BeginInvoke(DispatcherPriority.Normal, continuation); });
			return tcs.Task;
		}

		void CancelButton_Click(object sender, RoutedEventArgs e)
		{
			if (currentCancellationTokenSource != null)
			{
				currentCancellationTokenSource.Cancel();
				// Don't set to null: the task still needs to produce output and hide the wait adorner
			}
		}
		#endregion

		#region ShowOutput
		public void ShowText(AvalonEditTextOutput textOutput)
		{
			ShowNodes(textOutput, null);
		}

		public void ShowNode(AvalonEditTextOutput textOutput, ILSpyTreeNode node, IHighlightingDefinition? highlighting = null)
		{
			ShowNodes(textOutput, new[] { node }, highlighting);
		}

		/// <summary>
		/// Shows the given output in the text view.
		/// Cancels any currently running decompilation tasks.
		/// </summary>
		public void ShowNodes(AvalonEditTextOutput textOutput, ILSpyTreeNode[]? nodes, IHighlightingDefinition? highlighting = null)
		{
			// Cancel the decompilation task:
			if (currentCancellationTokenSource != null)
			{
				currentCancellationTokenSource.Cancel();
				currentCancellationTokenSource = null; // prevent canceled task from producing output
			}
			if (this.nextDecompilationRun != null)
			{
				// remove scheduled decompilation run
				this.nextDecompilationRun.TaskCompletionSource.TrySetCanceled();
				this.nextDecompilationRun = null;
			}
			if (nodes != null && (string.IsNullOrEmpty(textOutput.Title)
				|| textOutput.Title == Properties.Resources.NewTab))
			{
				textOutput.Title = string.Join(", ", nodes.Select(n => n.Text));
			}

			decompiledNodes = nodes;
			ShowOutput(textOutput, highlighting);
		}

		/// <summary>
		/// Shows the given output in the text view.
		/// </summary>
		void ShowOutput(AvalonEditTextOutput textOutput, IHighlightingDefinition? highlighting = null, DecompilerTextViewState? state = null)
		{
			Debug.WriteLine("Showing {0} characters of output", textOutput.TextLength);
			Stopwatch w = Stopwatch.StartNew();

			ClearLocalReferenceMarks();
			textEditor.ScrollToHome();
			if (foldingManager != null)
			{
				FoldingManager.Uninstall(foldingManager);
				foldingManager = null;
			}
			textEditor.Document = null; // clear old document while we're changing the highlighting
			uiElementGenerator.UIElements = textOutput.UIElements;
			referenceElementGenerator.References = textOutput.References;
			references = textOutput.References;
			definitionLookup = textOutput.DefinitionLookup;
			textEditor.SyntaxHighlighting = highlighting;
			textEditor.Options.EnableEmailHyperlinks = textOutput.EnableHyperlinks;
			textEditor.Options.EnableHyperlinks = textOutput.EnableHyperlinks;
			activeRichTextModel = null;
			if (activeRichTextColorizer != null)
				textEditor.TextArea.TextView.LineTransformers.Remove(activeRichTextColorizer);
			if (textOutput.HighlightingModel != null)
			{
				activeRichTextModel = textOutput.HighlightingModel;
				activeRichTextColorizer = new RichTextColorizer(textOutput.HighlightingModel);
				textEditor.TextArea.TextView.LineTransformers.Insert(highlighting == null ? 0 : 1, activeRichTextColorizer);
			}

			// Change the set of active element generators:
			foreach (var elementGenerator in activeCustomElementGenerators)
			{
				textEditor.TextArea.TextView.ElementGenerators.Remove(elementGenerator);
			}
			activeCustomElementGenerators.Clear();

			foreach (var elementGenerator in textOutput.elementGenerators)
			{
				textEditor.TextArea.TextView.ElementGenerators.Add(elementGenerator);
				activeCustomElementGenerators.Add(elementGenerator);
			}

			Debug.WriteLine("  Set-up: {0}", w.Elapsed);
			w.Restart();
			textEditor.Document = textOutput.GetDocument();
			Debug.WriteLine("  Assigning document: {0}", w.Elapsed);
			w.Restart();
			if (textOutput.Foldings.Count > 0)
			{
				if (state != null)
				{
					state.RestoreFoldings(textOutput.Foldings, settingsService.DisplaySettings.ExpandMemberDefinitions);
					textEditor.ScrollToVerticalOffset(state.VerticalOffset);
					textEditor.ScrollToHorizontalOffset(state.HorizontalOffset);
				}
				foldingManager = FoldingManager.Install(textEditor.TextArea);
				foldingManager.UpdateFoldings(textOutput.Foldings.OrderBy(f => f.StartOffset), -1);
				Debug.WriteLine("  Updating folding: {0}", w.Elapsed);
				w.Restart();
			}
			else if (highlighting?.Name == "XML")
			{
				foldingManager = FoldingManager.Install(textEditor.TextArea);
				var foldingStrategy = new XmlFoldingStrategy();
				foldingStrategy.UpdateFoldings(foldingManager, textEditor.Document);
				Debug.WriteLine("  Updating folding: {0}", w.Elapsed);
				w.Restart();
			}

			if (this.DataContext is PaneModel model)
			{
				model.Title = textOutput.Title;
			}
			currentAddress = textOutput.Address;
			currentTitle = textOutput.Title;
			expandMemberDefinitions = settingsService.DisplaySettings.ExpandMemberDefinitions;
		}
		#endregion

		#region Decompile (for display)
		// more than 5M characters is too slow to output (when user browses treeview)
		public const int DefaultOutputLengthLimit = 5000000;

		// more than 75M characters can get us into trouble with memory usage
		public const int ExtendedOutputLengthLimit = 75000000;

		DecompilationContext? nextDecompilationRun;

		[Obsolete("Use DecompileAsync() instead")]
		public void Decompile(ILSpy.Language language, IEnumerable<ILSpyTreeNode> treeNodes, DecompilationOptions options)
		{
			DecompileAsync(language, treeNodes, options).HandleExceptions();
		}

		/// <summary>
		/// Starts the decompilation of the given nodes.
		/// The result is displayed in the text view.
		/// If any errors occur, the error message is displayed in the text view, and the task returned by this method completes successfully.
		/// If the operation is cancelled (by starting another decompilation action); the returned task is marked as cancelled.
		/// </summary>
		public Task DecompileAsync(ILSpy.Language language, IEnumerable<ILSpyTreeNode> treeNodes, DecompilationOptions options)
		{
			// Some actions like loading an assembly list cause several selection changes in the tree view,
			// and each of those will start a decompilation action.

			bool isDecompilationScheduled = this.nextDecompilationRun != null;
			if (this.nextDecompilationRun != null)
				this.nextDecompilationRun.TaskCompletionSource.TrySetCanceled();
			this.nextDecompilationRun = new DecompilationContext(language, treeNodes.ToArray(), options);
			var task = this.nextDecompilationRun.TaskCompletionSource.Task;
			if (!isDecompilationScheduled)
			{
				Dispatcher.BeginInvoke(DispatcherPriority.Background, new Action(
					delegate {
						var context = this.nextDecompilationRun;
						this.nextDecompilationRun = null;
						if (context != null)
							DoDecompile(context, DefaultOutputLengthLimit)
								.ContinueWith(t => context.TaskCompletionSource.SetFromTask(t)).HandleExceptions();
					}
				));
			}
			return task;
		}

		sealed class DecompilationContext
		{
			public readonly ILSpy.Language Language;
			public readonly ILSpyTreeNode[] TreeNodes;
			public readonly DecompilationOptions Options;
			public readonly TaskCompletionSource<object?> TaskCompletionSource = new TaskCompletionSource<object?>();

			public DecompilationContext(ILSpy.Language language, ILSpyTreeNode[] treeNodes, DecompilationOptions options)
			{
				this.Language = language;
				this.TreeNodes = treeNodes;
				this.Options = options;
			}
		}

		Task DoDecompile(DecompilationContext context, int outputLengthLimit)
		{
			return RunWithCancellation(
				delegate (CancellationToken ct) { // creation of the background task
					context.Options.CancellationToken = ct;
					context.Options.Progress = this;
					decompiledNodes = context.TreeNodes;
					return DecompileAsync(context, outputLengthLimit);
				})
			.Then(
				delegate (AvalonEditTextOutput textOutput) { // handling the result
					ShowOutput(textOutput, context.Language.SyntaxHighlighting, context.Options.TextViewState);
				})
			.Catch<Exception>(exception => {
				textEditor.SyntaxHighlighting = null;
				Debug.WriteLine("Decompiler crashed: " + exception.ToString());
				AvalonEditTextOutput output = new AvalonEditTextOutput();
				if (exception is OutputLengthExceededException)
				{
					WriteOutputLengthExceededMessage(output, context, outputLengthLimit == DefaultOutputLengthLimit);
				}
				else
				{
					output.WriteLine(exception.ToString());
				}
				ShowOutput(output);
			});
		}

		Task<AvalonEditTextOutput> DecompileAsync(DecompilationContext context, int outputLengthLimit)
		{
			Debug.WriteLine("Start decompilation of {0} tree nodes", context.TreeNodes.Length);

			TaskCompletionSource<AvalonEditTextOutput> tcs = new TaskCompletionSource<AvalonEditTextOutput>();
			if (context.TreeNodes.Length == 0)
			{
				// If there's nothing to be decompiled, don't bother starting up a thread.
				// (Improves perf in some cases since we don't have to wait for the thread-pool to accept our task)
				tcs.SetResult(new AvalonEditTextOutput());
				return tcs.Task;
			}

			Thread thread = new Thread(new ThreadStart(
				delegate {
					try
					{
						AvalonEditTextOutput textOutput = new AvalonEditTextOutput();
						textOutput.LengthLimit = outputLengthLimit;
						DecompileNodes(context, textOutput);
						textOutput.PrepareDocument();
						tcs.SetResult(textOutput);
					}
					catch (OperationCanceledException)
					{
						tcs.SetCanceled();
					}
					catch (Exception ex)
					{
						tcs.SetException(ex);
					}
				}));
			thread.Start();
			return tcs.Task;
		}

		void DecompileNodes(DecompilationContext context, ITextOutput textOutput)
		{
			var nodes = context.TreeNodes;
			if (textOutput is ISmartTextOutput smartTextOutput)
			{
				smartTextOutput.Title = string.Join(", ", nodes.Select(n => n.Text));
			}
			for (int i = 0; i < nodes.Length; i++)
			{
				if (i > 0)
					textOutput.WriteLine();

				context.Options.CancellationToken.ThrowIfCancellationRequested();
				nodes[i].Decompile(context.Language, textOutput, context.Options);
			}
		}
		#endregion

		#region WriteOutputLengthExceededMessage
		/// <summary>
		/// Creates a message that the decompiler output was too long.
		/// The message contains buttons that allow re-trying (with larger limit) or saving to a file.
		/// </summary>
		void WriteOutputLengthExceededMessage(ISmartTextOutput output, DecompilationContext context, bool wasNormalLimit)
		{
			if (wasNormalLimit)
			{
				output.WriteLine("You have selected too much code for it to be displayed automatically.");
			}
			else
			{
				output.WriteLine("You have selected too much code; it cannot be displayed here.");
			}
			output.WriteLine();
			if (wasNormalLimit)
			{
				output.AddButton(
					Images.ViewCode, Properties.Resources.DisplayCode,
					delegate {
						DoDecompile(context, ExtendedOutputLengthLimit).HandleExceptions();
					});
				output.WriteLine();
			}

			output.AddButton(
				Images.Save, Properties.Resources.SaveCode,
				delegate {
					SaveToDisk(context.Language, context.TreeNodes, context.Options);
				});
			output.WriteLine();
		}
		#endregion

		#region JumpToReference
		/// <summary>
		/// Jumps to the definition referred to by the <see cref="ReferenceSegment"/>.
		/// </summary>
		internal void JumpToReference(ReferenceSegment referenceSegment, bool openInNewTab)
		{
			object reference = referenceSegment.Reference;
			if (referenceSegment.IsLocal)
			{
				ClearLocalReferenceMarks();
				if (references != null)
				{
					foreach (var r in references)
					{
						if (reference.Equals(r.Reference))
						{

							var mark = textMarkerService.Create(r.StartOffset, r.Length);
							mark.BackgroundColor = (Color)(r.IsDefinition ? FindResource(ResourceKeys.TextMarkerDefinitionBackgroundColor) : FindResource(ResourceKeys.TextMarkerBackgroundColor));
							localReferenceMarks.Add(mark);
						}
					}
				}
				return;
			}
			if (definitionLookup != null)
			{
				int pos = definitionLookup.GetDefinitionPosition(reference);
				if (pos >= 0)
				{
					textEditor.TextArea.Focus();
					textEditor.Select(pos, 0);
					textEditor.ScrollTo(textEditor.TextArea.Caret.Line, textEditor.TextArea.Caret.Column);
					Dispatcher.Invoke(DispatcherPriority.Background, new Action(
						delegate {
							CaretHighlightAdorner.DisplayCaretHighlightAnimation(textEditor.TextArea);
						}));
					return;
				}
			}
			MessageBus.Send(this, new NavigateToReferenceEventArgs(reference, openInNewTab));
		}

		Point? mouseDownPos;

		void TextAreaMouseDown(object sender, MouseButtonEventArgs e)
		{
			mouseDownPos = e.GetPosition(this);
		}

		void TextAreaMouseUp(object sender, MouseButtonEventArgs e)
		{
			if (mouseDownPos == null)
				return;
			Vector dragDistance = e.GetPosition(this) - mouseDownPos.Value;
			if (Math.Abs(dragDistance.X) < SystemParameters.MinimumHorizontalDragDistance
				&& Math.Abs(dragDistance.Y) < SystemParameters.MinimumVerticalDragDistance
				&& (e.ChangedButton == MouseButton.Left || e.ChangedButton == MouseButton.Middle))
			{
				// click without moving mouse
				var referenceSegment = GetReferenceSegmentAtMousePosition();
				if (referenceSegment == null)
				{
					ClearLocalReferenceMarks();
				}
				else if (referenceSegment.IsLocal || !referenceSegment.IsDefinition)
				{
					textEditor.TextArea.ClearSelection();
					// cancel mouse selection to avoid AvalonEdit selecting between the new
					// cursor position and the mouse position.
					textEditor.TextArea.MouseSelectionMode = MouseSelectionMode.None;

					JumpToReference(referenceSegment, e.ChangedButton == MouseButton.Middle || Keyboard.Modifiers.HasFlag(ModifierKeys.Shift));
				}
			}
		}

		void ClearLocalReferenceMarks()
		{
			foreach (var mark in localReferenceMarks)
			{
				textMarkerService.Remove(mark);
			}
			localReferenceMarks.Clear();
		}

		/// <summary>
		/// Filters all ReferenceSegments that are no real links.
		/// </summary>
		bool IsLink(ReferenceSegment referenceSegment)
		{
			return referenceSegment.IsLocal || !referenceSegment.IsDefinition;
		}
		#endregion

		#region SaveToDisk
		/// <summary>
		/// Shows the 'save file dialog', prompting the user to save the decompiled nodes to disk.
		/// </summary>
		public void SaveToDisk(ILSpy.Language language, IEnumerable<ILSpyTreeNode> treeNodes, DecompilationOptions options)
		{
			if (!treeNodes.Any())
				return;

			SaveFileDialog dlg = new SaveFileDialog();
			dlg.DefaultExt = language.FileExtension;
			dlg.Filter = language.Name + "|*" + language.FileExtension + Properties.Resources.AllFiles;
			dlg.FileName = WholeProjectDecompiler.CleanUpFileName(treeNodes.First().ToString(), language.FileExtension);
			if (dlg.ShowDialog() == true)
			{
				SaveToDisk(new DecompilationContext(language, treeNodes.ToArray(), options), dlg.FileName);
			}
		}

		public void SaveToDisk(ILSpy.Language language, IEnumerable<ILSpyTreeNode> treeNodes, DecompilationOptions options, string fileName)
		{
			SaveToDisk(new DecompilationContext(language, treeNodes.ToArray(), options), fileName);
		}

		/// <summary>
		/// Starts the decompilation of the given nodes.
		/// The result will be saved to the given file name.
		/// </summary>
		void SaveToDisk(DecompilationContext context, string fileName)
		{
			RunWithCancellation(
				delegate (CancellationToken ct) {
					context.Options.CancellationToken = ct;
					return SaveToDiskAsync(context, fileName);
				})
				.Then(output => ShowOutput(output))
				.Catch((Exception ex) => {
					textEditor.SyntaxHighlighting = null;
					Debug.WriteLine("Decompiler crashed: " + ex.ToString());
					// Unpack aggregate exceptions as long as there's only a single exception:
					// (assembly load errors might produce nested aggregate exceptions)
					AvalonEditTextOutput output = new AvalonEditTextOutput();
					output.WriteLine(ex.ToString());
					ShowOutput(output);
				}).HandleExceptions();
		}

		Task<AvalonEditTextOutput> SaveToDiskAsync(DecompilationContext context, string fileName)
		{
			TaskCompletionSource<AvalonEditTextOutput> tcs = new TaskCompletionSource<AvalonEditTextOutput>();
			Thread thread = new Thread(new ThreadStart(
				delegate {
					try
					{
						bool originalProjectFormatSetting = context.Options.DecompilerSettings.UseSdkStyleProjectFormat;
						context.Options.EscapeInvalidIdentifiers = true;
						context.Options.Progress = this;
						AvalonEditTextOutput output = new AvalonEditTextOutput {
							EnableHyperlinks = true,
							Title = string.Join(", ", context.TreeNodes.Select(n => n.Text))
						};
						Stopwatch stopwatch = new Stopwatch();
						stopwatch.Start();
						try
						{
							using (StreamWriter w = new StreamWriter(fileName))
							{
								try
								{
									DecompileNodes(context, new PlainTextOutput(w));
								}
								catch (OperationCanceledException)
								{
									w.WriteLine();
									w.WriteLine(Properties.Resources.DecompilationWasCancelled);
									throw;
								}
								catch (PathTooLongException pathTooLong) when (context.Options.SaveAsProjectDirectory != null)
								{
									output.WriteLine(Properties.Resources.ProjectExportPathTooLong, string.Join(", ", context.TreeNodes.Select(n => n.Text)));
									output.WriteLine();
									output.WriteLine(pathTooLong.ToString());
									tcs.SetResult(output);
									return;
								}
							}
						}
						finally
						{
							stopwatch.Stop();
						}

						output.WriteLine(Properties.Resources.DecompilationCompleteInF1Seconds, stopwatch.Elapsed.TotalSeconds);
						if (context.Options.SaveAsProjectDirectory != null)
						{
							output.WriteLine();
							bool useSdkStyleProjectFormat = context.Options.DecompilerSettings.UseSdkStyleProjectFormat;
							if (useSdkStyleProjectFormat)
							{
								output.WriteLine(Properties.Resources.ProjectExportFormatSDKHint);
							}
							else
							{
								output.WriteLine(Properties.Resources.ProjectExportFormatNonSDKHint);
							}
							output.WriteLine(Properties.Resources.ProjectExportFormatChangeSettingHint);
							if (originalProjectFormatSetting != useSdkStyleProjectFormat)
							{
								output.WriteLine(Properties.Resources.CouldNotUseSdkStyleProjectFormat);
							}
						}
						output.WriteLine();
						output.AddButton(null, Properties.Resources.OpenExplorer, delegate { Process.Start("explorer", "/select,\"" + fileName + "\""); });
						output.WriteLine();
						tcs.SetResult(output);
					}
					catch (OperationCanceledException)
					{
						tcs.SetCanceled();
					}
					catch (Exception ex)
					{
						tcs.SetException(ex);
					}
				}));
			thread.Start();
			return tcs.Task;
		}
		#endregion

		#region Clipboard
		private void OnSettingData(object sender, DataObjectSettingDataEventArgs e)
		{
			if (e.Format == DataFormats.Html && e.DataObject is DataObject dataObject)
			{
				e.CancelCommand();
				HtmlClipboard.SetHtml(dataObject, CreateHtmlFragmentFromSelection());
			}
		}

		private string CreateHtmlFragmentFromSelection()
		{
			var options = new HtmlOptions(textEditor.TextArea.Options);
			var highlighter = textEditor.TextArea.GetService(typeof(IHighlighter)) as IHighlighter;
			var html = new StringBuilder();

			foreach (var segment in textEditor.TextArea.Selection.Segments)
			{
				var line = textEditor.Document.GetLineByOffset(segment.StartOffset);

				while (line != null && line.Offset < segment.EndOffset)
				{
					if (html.Length > 0)
						html.AppendLine("<br>");

					var s = GetOverlap(segment, line);
					var highlightedLine = highlighter?.HighlightLine(line.LineNumber) ?? new HighlightedLine(textEditor.Document, line);

					if (activeRichTextModel is not null)
					{
						var richTextHighlightedLine = new HighlightedLine(textEditor.Document, line);
						foreach (HighlightedSection richTextSection in activeRichTextModel.GetHighlightedSections(s.Offset, s.Length))
							richTextHighlightedLine.Sections.Add(richTextSection);
						highlightedLine.MergeWith(richTextHighlightedLine);
					}

					html.Append(highlightedLine.ToHtml(s.Offset, s.Offset + s.Length, options));
					line = line.NextLine;
				}
			}

			return html.ToString();

			static (int Offset, int Length) GetOverlap(ISegment segment1, ISegment segment2)
			{
				int start = Math.Max(segment1.Offset, segment2.Offset);
				int end = Math.Min(segment1.EndOffset, segment2.EndOffset);
				return (start, end - start);
			}
		}
		#endregion

		internal ReferenceSegment? GetReferenceSegmentAtMousePosition()
		{
			if (referenceElementGenerator.References == null)
				return null;
			TextViewPosition? position = GetPositionFromMousePosition();
			if (position == null)
				return null;
			int offset = textEditor.Document.GetOffset(position.Value.Location);
			return referenceElementGenerator.References.FindSegmentsContaining(offset).FirstOrDefault();
		}

		internal TextViewPosition? GetPositionFromMousePosition()
		{
			var position = textEditor.TextArea.TextView.GetPosition(Mouse.GetPosition(textEditor.TextArea.TextView) + textEditor.TextArea.TextView.ScrollOffset);
			if (position == null)
				return null;
			var lineLength = textEditor.Document.GetLineByNumber(position.Value.Line).Length + 1;
			if (position.Value.Column == lineLength)
				return null;
			return position;
		}

		public DecompilerTextViewState? GetState()
		{
			if (decompiledNodes == null && currentAddress == null)
				return null;

			var state = new DecompilerTextViewState();
			if (foldingManager != null)
				state.SaveFoldingsState(foldingManager.AllFoldings);
			state.VerticalOffset = textEditor.VerticalOffset;
			state.HorizontalOffset = textEditor.HorizontalOffset;
			state.ExpandMemberDefinitions = expandMemberDefinitions;
			state.DecompiledNodes = decompiledNodes == null ? null : new HashSet<ILSpyTreeNode>(decompiledNodes);
			state.ViewedUri = currentAddress;
			return state;
		}

		ViewState? IHaveState.GetState() => GetState();

		public static void RegisterHighlighting()
		{
			HighlightingManager.Instance.RegisterHighlighting("ILAsm", new[] { ".il" }, "ILAsm-Mode");
			HighlightingManager.Instance.RegisterHighlighting("C#", new[] { ".cs" }, "CSharp-Mode");
			HighlightingManager.Instance.RegisterHighlighting("Asm", new[] { ".s", ".asm" }, "Asm-Mode");
			HighlightingManager.Instance.RegisterHighlighting("xml", new[] { ".xml", ".baml" }, "XML-Mode");
		}

		#region Unfold
		public void UnfoldAndScroll(int lineNumber)
		{
			if (lineNumber <= 0 || lineNumber > textEditor.Document.LineCount)
				return;
			if (foldingManager == null)
				return;

			var line = textEditor.Document.GetLineByNumber(lineNumber);

			// unfold
			var foldings = foldingManager.GetFoldingsContaining(line.Offset);
			if (foldings != null)
			{
				foreach (var folding in foldings)
				{
					if (folding.IsFolded)
					{
						folding.IsFolded = false;
					}
				}
			}
			// scroll to
			textEditor.ScrollTo(lineNumber, 0);
		}

		public FoldingManager? FoldingManager {
			get {
				return foldingManager;
			}
		}
		#endregion
	}

	[DebuggerDisplay("Nodes = {DecompiledNodes}, ViewedUri = {ViewedUri}")]
	public class ViewState : IEquatable<ViewState>
	{
		public HashSet<ILSpyTreeNode>? DecompiledNodes;
		public Uri? ViewedUri;

		public virtual bool Equals(ViewState? other)
		{
			return other != null
				&& ViewedUri == other.ViewedUri
				&& NullSafeSetEquals(DecompiledNodes, other.DecompiledNodes);

			static bool NullSafeSetEquals(HashSet<ILSpyTreeNode>? a, HashSet<ILSpyTreeNode>? b)
			{
				if (a == b)
					return true;
				if (a == null || b == null)
					return false;
				return a.SetEquals(b);
			}
		}
	}

	public class DecompilerTextViewState : ViewState
	{
		private List<(int StartOffset, int EndOffset)>? ExpandedFoldings;
		private int FoldingsChecksum;
		public bool ExpandMemberDefinitions;
		public double VerticalOffset;
		public double HorizontalOffset;

		public void SaveFoldingsState(IEnumerable<FoldingSection> foldings)
		{
			ExpandedFoldings = foldings.Where(f => !f.IsFolded)
				.Select(f => (f.StartOffset, f.EndOffset)).ToList();
			FoldingsChecksum = unchecked(foldings.Select(f => f.StartOffset * 3 - f.EndOffset)
				.DefaultIfEmpty()
				.Aggregate((a, b) => a + b));
		}

		internal void RestoreFoldings(List<NewFolding> list, bool expandMemberDefinitions)
		{
			if (ExpandedFoldings == null)
				return;
			var checksum = unchecked(list.Select(f => f.StartOffset * 3 - f.EndOffset)
				.DefaultIfEmpty()
				.Aggregate((a, b) => a + b));
			if (FoldingsChecksum == checksum)
			{
				foreach (var folding in list)
				{
					bool wasExpanded = ExpandedFoldings.Any(
						f => f.StartOffset == folding.StartOffset
							&& f.EndOffset == folding.EndOffset
					);
					bool isExpanded = !folding.DefaultClosed;
					// State of the folding was changed
					if (wasExpanded != isExpanded)
					{
						// The "ExpandMemberDefinitions" setting was not changed
						if (expandMemberDefinitions == ExpandMemberDefinitions)
						{
							// restore fold state
							folding.DefaultClosed = !wasExpanded;
						}
						else
						{
							// only restore fold state if fold was not a definition
							if (!folding.IsDefinition)
							{
								folding.DefaultClosed = !wasExpanded;
							}
						}
					}
				}
			}
		}

		public override bool Equals(ViewState? other)
		{
			if (other is DecompilerTextViewState vs)
			{
				return base.Equals(vs)
					&& FoldingsChecksum == vs.FoldingsChecksum
					&& VerticalOffset == vs.VerticalOffset
					&& HorizontalOffset == vs.HorizontalOffset;
			}
			return false;
		}
	}

	static class ExtensionMethods
	{
		public static void RegisterHighlighting(
			this HighlightingManager manager,
			string name,
			string[] extensions,
			string resourceName)
		{
			Stream? resourceStream = typeof(DecompilerTextView).Assembly
				.GetManifestResourceStream(typeof(DecompilerTextView), resourceName + ".xshd");

			if (resourceStream != null)
			{
				IHighlightingDefinition highlightingDefinition;

				using (resourceStream)
				using (XmlTextReader reader = new XmlTextReader(resourceStream))
				{
					highlightingDefinition = HighlightingLoader.Load(reader, manager);
				}

				manager.RegisterHighlighting(
				name, extensions,
				delegate {
					ThemeManager.Current.ApplyHighlightingColors(highlightingDefinition);
					return highlightingDefinition;
				});
			}
		}
	}
}