// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
//
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using System;
using System.Linq;
using System.Threading.Tasks;

using Avalonia.Controls;
using Avalonia.Headless.NUnit;

using AwesomeAssertions;

using ILSpy.AppEnv;
using ILSpy.AssemblyTree;
using ILSpy.TextView;
using ILSpy.TreeNodes;
using ILSpy.ViewModels;
using ILSpy.Views;

using NUnit.Framework;

namespace ICSharpCode.ILSpy.Tests;

[TestFixture]
public class CaretHighlightAdornerTests
{
	// audit (2026-05-12):
	//   * catches commenting out `BackgroundRenderers.Add(adorner)` in
	//     CaretHighlightAdorner.DisplayCaretHighlightAnimation (the "registered" assertion).
	//   * catches commenting out the `CaretHighlightAdorner.DisplayCaretHighlightAnimation(...)`
	//     call inside DecompilerTextView.OnReferenceClicked — the integration path the test
	//     drives. A direct unit test on DisplayCaretHighlightAnimation would not have caught
	//     this regression.
	[AvaloniaTest]
	public async Task Clicking_A_Member_Definition_In_The_Decompiled_Output_Triggers_Caret_Highlight()
	{
		// Integration test for the caret-highlight gesture: select a type, wait for the
		// decompile to populate the editor + reference collection, then drive the same
		// `ReferenceElementGenerator.OnReferenceClicked` entry point that a real
		// `VisualLineReferenceText.OnPointerPressed` fires when the user clicks a member
		// name. Member definitions register themselves in `DefinitionLookup` (see
		// AvaloniaEditTextOutput.AddReference), so `OnReferenceClicked` resolves the click
		// to an in-document jump and DecompilerTextView fires the caret highlight.
		//
		// The lifecycle (register then unregister after ~1 s) is verified end-to-end —
		// hand-tuned animation curve is left for eyeball validation.
		var window = AppComposition.Current.GetExport<MainWindow>();
		window.Show();
		var vm = (MainWindowViewModel)window.DataContext!;
		await vm.AssemblyTreeModel.WaitForAssembliesAsync(minimumCount: 1);
		// Decompile a single method instead of the whole Enumerable type — the full type
		// takes >15 s in headless and flakes WaitForDecompiledTextAsync. `Empty<TSource>`
		// is one of the smallest methods and still emits a member-definition reference
		// (the method name) plus type-definition references on its return type.
		var typeNode = vm.AssemblyTreeModel.FindNode<TypeTreeNode>(
			"System.Linq", "System.Linq", "System.Linq.Enumerable");
		typeNode.IsExpanded = true;
		var method = typeNode.Children.OfType<MethodTreeNode>()
			.First(m => m.MethodDefinition.Name == "Empty");
		vm.AssemblyTreeModel.SelectNode(method);
		await vm.DockWorkspace.WaitForDecompiledTextAsync();

		var view = await window.WaitForComponent<DecompilerTextView>();
		var editor = await view.WaitForComponent<AvaloniaEdit.TextEditor>();
		var renderers = editor.TextArea.TextView.BackgroundRenderers;

		// Sanity check — no adorner from a previous gesture is hanging around.
		renderers.Should().NotContain(r => r is CaretHighlightAdorner,
			"the test starts before any caret-highlight gesture is triggered");

		// Locate the live ReferenceElementGenerator and an in-document member-definition
		// segment (the spot where the member's name is written; IsDefinition=true causes
		// DefinitionLookup to register the entity + offset together, so OnReferenceClicked's
		// in-document branch is guaranteed to fire).
		var generator = editor.TextArea.TextView.ElementGenerators
			.OfType<ReferenceElementGenerator>().Single();
		generator.References.Should().NotBeNull(
			"DecompilerTextView assigns the live References collection on every ApplyDocument");
		var memberDef = generator.References!
			.FirstOrDefault(s => s.IsDefinition && !s.IsLocal && s.Reference != null);
		((object?)memberDef).Should().NotBeNull(
			"the decompiled Enumerable class contains at least one member-definition reference");

		// Same code path a real pointer-press on the member name routes through.
		generator.OnReferenceClicked(memberDef!);

		renderers.Should().Contain(r => r is CaretHighlightAdorner,
			"clicking a member definition must route through DecompilerTextView.OnReferenceClicked "
			+ "and call CaretHighlightAdorner.DisplayCaretHighlightAnimation");

		// Wait for the lifetime timer (~1 s) to tear it back down.
		await Waiters.WaitForAsync(
			() => !renderers.Any(r => r is CaretHighlightAdorner),
			timeout: TimeSpan.FromSeconds(3));
	}
}