// 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.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.Composition;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Reflection.Metadata;
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;
using ICSharpCode.Decompiler.CSharp.OutputVisitor;
using ICSharpCode.Decompiler.Documentation;
using ICSharpCode.Decompiler.Metadata;
using ICSharpCode.Decompiler.Output;
using ICSharpCode.Decompiler.TypeSystem;
using ICSharpCode.ILSpy.AvalonEdit;
using ICSharpCode.ILSpy.Options;
using ICSharpCode.ILSpy.TreeNodes;
using ICSharpCode.ILSpy.ViewModels;
using Microsoft.Win32;

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, IDisposable, IHaveState
	{
		readonly ReferenceElementGenerator referenceElementGenerator;
		readonly UIElementGenerator uiElementGenerator;
		readonly List<VisualLineElementGenerator> activeCustomElementGenerators = new List<VisualLineElementGenerator>();
		RichTextColorizer activeRichTextColorizer;
		BracketHighlightRenderer bracketHighlightRenderer;
		FoldingManager foldingManager;
		ILSpyTreeNode[] decompiledNodes;
		Uri currentAddress;
		
		DefinitionLookup definitionLookup;
		TextSegmentCollection<ReferenceSegment> references;
		CancellationTokenSource currentCancellationTokenSource;
		
		readonly TextMarkerService textMarkerService;
		readonly List<ITextMarker> localReferenceMarks = new List<ITextMarker>();
		
		#region Constructor
		public DecompilerTextView()
		{
			HighlightingManager.Instance.RegisterHighlighting(
				"ILAsm", new string[] { ".il" },
				delegate {
					using (Stream s = typeof(DecompilerTextView).Assembly.GetManifestResourceStream(typeof(DecompilerTextView), "ILAsm-Mode.xshd")) {
						using (XmlTextReader reader = new XmlTextReader(s)) {
							return HighlightingLoader.Load(reader, HighlightingManager.Instance);
						}
					}
				});

			HighlightingManager.Instance.RegisterHighlighting(
				"C#", new string[] { ".cs" },
				delegate {
					using (Stream s = typeof(DecompilerTextView).Assembly.GetManifestResourceStream(typeof(DecompilerTextView), "CSharp-Mode.xshd")) {
						using (XmlTextReader reader = new XmlTextReader(s)) {
							return HighlightingLoader.Load(reader, HighlightingManager.Instance);
						}
					}
				});

			HighlightingManager.Instance.RegisterHighlighting(
				"Asm", new string[] { ".s", ".asm" },
				delegate {
					using (Stream s = typeof(DecompilerTextView).Assembly.GetManifestResourceStream(typeof(DecompilerTextView), "Asm-Mode.xshd")) {
						using (XmlTextReader reader = new XmlTextReader(s)) {
							return HighlightingLoader.Load(reader, HighlightingManager.Instance);
						}
					}
				});

			InitializeComponent();

			this.referenceElementGenerator = new ReferenceElementGenerator(this.JumpToReference, 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 = DisplaySettingsPanel.CurrentDisplaySettings, Path = new PropertyPath("SelectedFont") });
			textEditor.SetBinding(Control.FontSizeProperty, new Binding { Source = DisplaySettingsPanel.CurrentDisplaySettings, Path = new PropertyPath("SelectedFontSize") });
			textEditor.SetBinding(TextEditor.WordWrapProperty, new Binding { Source = DisplaySettingsPanel.CurrentDisplaySettings, 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;
			DisplaySettingsPanel.CurrentDisplaySettings.PropertyChanged += CurrentDisplaySettings_PropertyChanged;

			// SearchPanel
			SearchPanel.Install(textEditor.TextArea)
				.RegisterCommands(Application.Current.MainWindow.CommandBindings);
			
			ShowLineMargin();
			
			// add marker service & margin
			textEditor.TextArea.TextView.BackgroundRenderers.Add(textMarkerService);
			textEditor.TextArea.TextView.LineTransformers.Add(textMarkerService);

			ContextMenuProvider.Add(this);
		}

		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

		void CurrentDisplaySettings_PropertyChanged(object sender, PropertyChangedEventArgs e)
		{
			if (e.PropertyName == "ShowLineNumbers") {
				ShowLineMargin();
			}
		}
		
		void ShowLineMargin()
		{
			foreach (var margin in this.textEditor.TextArea.LeftMargins) {
				if (margin is LineNumberMargin || margin is System.Windows.Shapes.Line) {
					margin.Visibility = DisplaySettingsPanel.CurrentDisplaySettings.ShowLineNumbers ? Visibility.Visible : Visibility.Collapsed;
				}
			}
		}

		#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.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);
			Point positionInPixels;
			// align Popup with line bottom
			TextViewPosition? logicalPos = textEditor.GetPositionFromPoint(mousePos);
			if (logicalPos.HasValue) {
				var textView = textEditor.TextArea.TextView;
				positionInPixels =
					textView.PointToScreen(
						textView.GetVisualPosition(logicalPos.Value, VisualYPosition.LineBottom) - textView.ScrollOffset);
				positionInPixels.X -= 4;
			} else {
				positionInPixels = PointToScreen(mousePos + new Vector(-4, 6));
			}
			// use device independent units, because Popup Left/Top are in independent units
			return positionInPixels.TransformFromDevice(this);
		}

		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) {
				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
				popupToolTip.Closed -= ToolTipClosed;
				popupToolTip = null;
			}
		}

		object GenerateTooltip(ReferenceSegment segment)
		{
			if (segment.Reference is ICSharpCode.Decompiler.Disassembler.OpCodeInfo code) {
				XmlDocumentationProvider docProvider = XmlDocLoader.MscorlibDocumentation;
				DocumentationUIBuilder renderer = new DocumentationUIBuilder(new CSharpAmbience(), MainWindow.Instance.CurrentLanguage.SyntaxHighlighting);
				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());
			} else if (segment.Reference is IEntity entity) {
				var document = CreateTooltipForEntity(entity);
				if (document == null)
					return null;
				return new FlowDocumentTooltip(document);
			} else if (segment.Reference is EntityReference unresolvedEntity) {
				var typeSystem = new DecompilerTypeSystem(unresolvedEntity.Module, unresolvedEntity.Module.GetAssemblyResolver(), TypeSystemOptions.Default | TypeSystemOptions.Uncached);
				try {
					IEntity resolved = typeSystem.MainModule.ResolveEntity((EntityHandle)unresolvedEntity.Handle);
					if (resolved == null)
						return null;
					var document = CreateTooltipForEntity(resolved);
					if (document == null)
						return null;
					return new FlowDocumentTooltip(document);
				} catch (BadImageFormatException) {
					return null;
				}
			}
			return null;
		}

		static FlowDocument CreateTooltipForEntity(IEntity resolved)
		{
			Language currentLanguage = MainWindow.Instance.CurrentLanguage;
			DocumentationUIBuilder renderer = new DocumentationUIBuilder(new CSharpAmbience(), currentLanguage.SyntaxHighlighting);
			RichText richText = currentLanguage.GetRichTextTooltip(resolved);
			renderer.AddSignatureBlock(richText.Text, richText.ToRichTextModel());
			try {
				if (resolved.ParentModule == null || resolved.ParentModule.PEFile == null)
					return null;
				var docProvider = XmlDocLoader.LoadDocumentation(resolved.ParentModule.PEFile);
				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)
			{
				return MainWindow.FindEntityInRelevantAssemblies(idString, MainWindow.Instance.CurrentAssemblyList.GetAssemblies());
			}
		}

		sealed class FlowDocumentTooltip : Popup
		{
			readonly FlowDocumentScrollViewer viewer;

			public FlowDocumentTooltip(FlowDocument document)
			{
				TextOptions.SetTextFormattingMode(this, TextFormattingMode.Display);
				double fontSize = DisplaySettingsPanel.CurrentDisplaySettings.SelectedFontSize;
				viewer = new FlowDocumentScrollViewer() {
					Width = document.MinPageWidth + fontSize * 5,
					MaxWidth = MainWindow.Instance.ActualWidth
				};
				viewer.Document = document;
				Border border = new Border {
					Background = SystemColors.ControlBrush,
					BorderBrush = SystemColors.ControlDarkBrush,
					BorderThickness = new Thickness(1),
					MaxHeight = 400,
					Child = viewer
				};
				this.Child = border;
				viewer.Foreground = SystemColors.InfoTextBrush;
				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 (DisplaySettingsPanel.CurrentDisplaySettings.HighlightMatchingBraces) {
				var result = MainWindow.Instance.CurrentLanguage.BracketSearcher.SearchBracket(textEditor.Document, textEditor.CaretOffset);
				bracketHighlightRenderer.SetHighlight(result);
			} else {
				bracketHighlightRenderer.SetHighlight(null);
			}
		}
		#endregion

		#region RunWithCancellation
		/// <summary>
		/// Switches the GUI into "waiting" mode, then calls <paramref name="taskCreation"/> to create
		/// the task.
		/// When the task completes without being cancelled, the <paramref name="taskCompleted"/>
		/// callback is called on the GUI thread.
		/// When the task is cancelled before completing, the callback is not called; and any result
		/// of the task (including exceptions) are ignored.
		/// </summary>
		[Obsolete("RunWithCancellation(taskCreation).ContinueWith(taskCompleted) instead")]
		public void RunWithCancellation<T>(Func<CancellationToken, Task<T>> taskCreation, Action<Task<T>> taskCompleted)
		{
			RunWithCancellation(taskCreation).ContinueWith(taskCompleted, CancellationToken.None, TaskContinuationOptions.NotOnCanceled, TaskScheduler.FromCurrentSynchronizationContext());
		}
		
		/// <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)
		{
			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
				progressBar.IsIndeterminate = true;
				waitAdorner.BeginAnimation(OpacityProperty, new DoubleAnimation(0, 1, new Duration(TimeSpan.FromSeconds(0.5)), FillBehavior.Stop));
				var taskBar = MainWindow.Instance.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;
						var taskBar = MainWindow.Instance.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 = string.Join(", ", nodes.Select(n => n.Text));
			ShowOutput(textOutput, highlighting);
			decompiledNodes = nodes;
		}
		
		/// <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;
			if (activeRichTextColorizer != null)
				textEditor.TextArea.TextView.LineTransformers.Remove(activeRichTextColorizer);
			if (textOutput.HighlightingModel != null) {
				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);
					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;
		}
		#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;
					return DecompileAsync(context, outputLengthLimit);
				})
			.Then(
				delegate (AvalonEditTextOutput textOutput) { // handling the result
					ShowOutput(textOutput, context.Language.SyntaxHighlighting, context.Options.TextViewState);
					decompiledNodes = context.TreeNodes;
				})
			.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);
					decompiledNodes = context.TreeNodes;
				});
		}
		
		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)
		{
			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 = r.IsDefinition ? Colors.LightSeaGreen : Colors.GreenYellow;
							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;
				}
			}
			MainWindow.Instance.JumpToReference(reference);
		}

		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)
			{
				// 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);
				}
			}
		}
		
		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 = CleanUpName(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 {
						context.Options.EscapeInvalidIdentifiers = true;
						Stopwatch stopwatch = new Stopwatch();
						stopwatch.Start();
						using (StreamWriter w = new StreamWriter(fileName)) {
							try {
								DecompileNodes(context, new PlainTextOutput(w));
							} catch (OperationCanceledException) {
								w.WriteLine();
								w.WriteLine("Decompiled was cancelled.");
								throw;
							}
						}
						stopwatch.Stop();
						AvalonEditTextOutput output = new AvalonEditTextOutput();
						output.WriteLine("Decompilation complete in " + stopwatch.Elapsed.TotalSeconds.ToString("F1") + " seconds.");
						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;
		}
		
		/// <summary>
		/// Cleans up a node name for use as a file name.
		/// </summary>
		internal static string CleanUpName(string text)
		{
			return WholeProjectDecompiler.CleanUpFileName(text);
		}
		#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.DecompiledNodes = decompiledNodes == null ? null : new HashSet<ILSpyTreeNode>(decompiledNodes);
			state.ViewedUri = currentAddress;
			return state;
		}

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

		public void Dispose()
		{
			DisplaySettingsPanel.CurrentDisplaySettings.PropertyChanged -= CurrentDisplaySettings_PropertyChanged;
		}
		
		#region Unfold
		public void UnfoldAndScroll(int lineNumber)
		{
			if (lineNumber <= 0 || lineNumber > textEditor.Document.LineCount)
				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
				&& (DecompiledNodes == other.DecompiledNodes || DecompiledNodes?.SetEquals(other.DecompiledNodes) == true);
		}
	}
	
	public class DecompilerTextViewState : ViewState
	{
		private List<Tuple<int, int>> ExpandedFoldings;
		private int FoldingsChecksum;
		public double VerticalOffset;
		public double HorizontalOffset;

		public void SaveFoldingsState(IEnumerable<FoldingSection> foldings)
		{
			ExpandedFoldings = foldings.Where(f => !f.IsFolded).Select(f => Tuple.Create(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)
		{
			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)
					folding.DefaultClosed = !ExpandedFoldings.Any(f => f.Item1 == folding.StartOffset && f.Item2 == folding.EndOffset);
		}

		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;
		}
	}
}