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

using Avalonia;
using Avalonia.Controls;
using Avalonia.Headless;
using Avalonia.Headless.NUnit;
using Avalonia.Input;
using Avalonia.VisualTree;

using AwesomeAssertions;

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

using NUnit.Framework;

namespace ICSharpCode.ILSpy.Tests.Input;

/// <summary>
/// Drives a real <see cref="HeadlessWindowExtensions.MouseDown"/> event through the
/// input pipeline so the MMB → "open in new tab" gesture is verified end-to-end
/// rather than via a synthetic <c>OpenNodeInNewTab</c> call. Catches routing regressions
/// (the existing synthetic tests would pass even if the PointerPressed handler stopped
/// being installed).
/// </summary>
[TestFixture]
public class HeadlessMmbPointerTests
{
	[AvaloniaTest]
	public async Task Middle_Click_On_An_Assembly_Tree_Row_Opens_A_New_Decompiler_Tab()
	{
		// Boot + load enough assemblies that we have visible rows.
		var window = AppComposition.Current.GetExport<MainWindow>();
		window.Show();
		var vm = (MainWindowViewModel)window.DataContext!;
		await vm.AssemblyTreeModel.WaitForAssembliesAsync(minimumCount: 1);

		var pane = await window.WaitForComponent<AssemblyListPane>();
		var grid = await pane.WaitForComponent<global::ILSpy.Controls.TreeView.SharpTreeView>();

		// Any realised SharpTreeViewItem whose DataContext is an ILSpyTreeNode is a valid click
		// target — the exact node doesn't matter, only that the gesture pipeline fires.
		await Waiters.WaitForAsync(() => grid.GetVisualDescendants().OfType<global::ILSpy.Controls.TreeView.SharpTreeViewItem>()
			.Any(r => r.DataContext is ILSpyTreeNode));
		var row = grid.GetVisualDescendants().OfType<global::ILSpy.Controls.TreeView.SharpTreeViewItem>()
			.First(r => r.DataContext is ILSpyTreeNode);

		// Snapshot the tab count BEFORE the gesture so we can assert a strict +1 after.
		var documents = ((ILSpyDockFactory)vm.DockWorkspace.Factory).Documents!;
		int before = documents.VisibleDockables?.Count ?? 0;

		// Translate the row's centre into TopLevel coordinates so MouseDown lands inside it.
		var topLevel = TopLevel.GetTopLevel(row)!;
		var rowBounds = row.Bounds;
		// Tree rows stretch to content width (with horizontal scroll), so clamp the click X to the
		// visible grid viewport — the row centre can sit off-screen past the grid's right edge.
		var centreInRow = new Point(System.Math.Min(rowBounds.Width, grid.Bounds.Width) / 2, rowBounds.Height / 2);
		var centreInTopLevel = row.TranslatePoint(centreInRow, topLevel)
			?? throw new System.InvalidOperationException("Row not in TopLevel visual tree");

		// Real pointer event — exercises bubble + handledEventsToo routing through SharpTreeView.
		topLevel.MouseDown(centreInTopLevel, MouseButton.Middle);
		topLevel.MouseUp(centreInTopLevel, MouseButton.Middle);

		// Wait for the tab to land. Without WaitForAsync this races the async decompile path.
		await Waiters.WaitForAsync(() => (documents.VisibleDockables?.Count ?? 0) > before);

		(documents.VisibleDockables?.Count ?? 0).Should().Be(before + 1);
	}

	[AvaloniaTest]
	public async Task Ctrl_LMB_On_An_Assembly_Tree_Row_Does_Not_Open_A_New_Tab()
	{
		// Ctrl+LMB previously did double duty: the tree's Extended-selection mode treats
		// it as "toggle this row in the multi-selection", and our OnTreePointerPressed
		// also treated it as "open in new tab". Both fired on a single click, so users
		// trying to extend a multi-selection ended up spawning unwanted tabs. The intended
		// gesture for "open in new tab" is MMB (matches WPF's DecompileInNewViewCommand
		// InputGestureText). Pin the corrected behaviour: Ctrl+LMB must NOT open a tab —
		// any future regression that re-adds the branch fails this test.

		var window = AppComposition.Current.GetExport<MainWindow>();
		window.Show();
		var vm = (MainWindowViewModel)window.DataContext!;
		await vm.AssemblyTreeModel.WaitForAssembliesAsync(minimumCount: 1);

		var pane = await window.WaitForComponent<AssemblyListPane>();
		var grid = await pane.WaitForComponent<global::ILSpy.Controls.TreeView.SharpTreeView>();

		await Waiters.WaitForAsync(() => grid.GetVisualDescendants().OfType<global::ILSpy.Controls.TreeView.SharpTreeViewItem>()
			.Any(r => r.DataContext is ILSpyTreeNode));
		var row = grid.GetVisualDescendants().OfType<global::ILSpy.Controls.TreeView.SharpTreeViewItem>()
			.First(r => r.DataContext is ILSpyTreeNode);

		var documents = ((ILSpyDockFactory)vm.DockWorkspace.Factory).Documents!;
		int before = documents.VisibleDockables?.Count ?? 0;

		var topLevel = TopLevel.GetTopLevel(row)!;
		var rowBounds = row.Bounds;
		// Tree rows stretch to content width (with horizontal scroll), so clamp the click X to the
		// visible grid viewport — the row centre can sit off-screen past the grid's right edge.
		var centreInRow = new Point(System.Math.Min(rowBounds.Width, grid.Bounds.Width) / 2, rowBounds.Height / 2);
		var centreInTopLevel = row.TranslatePoint(centreInRow, topLevel)
			?? throw new System.InvalidOperationException("Row not in TopLevel visual tree");

		topLevel.MouseDown(centreInTopLevel, MouseButton.Left, RawInputModifiers.Control);
		topLevel.MouseUp(centreInTopLevel, MouseButton.Left, RawInputModifiers.Control);

		// Give the (former) "open new tab" path a beat to land if it were going to.
		await Task.Delay(250);
		global::Avalonia.Threading.Dispatcher.UIThread.RunJobs();

		(documents.VisibleDockables?.Count ?? 0).Should().Be(before,
			"Ctrl+LMB must be reserved for the tree's multi-selection toggle — only MMB opens a new tab");
	}

	[AvaloniaTest]
	public async Task LMB_Double_Click_On_An_Internal_Tree_Row_Expands_Without_Opening_A_New_Tab()
	{
		// LMB double-click is WPF's expand/collapse gesture. The OnTreeGridDoubleTapped handler
		// is supposed to be the only path that fires; an earlier patch had OnTreeGridPointerPressed
		// also treating double-click as a "open in new tab" gesture, which produced both effects
		// at once. Pin the behaviour so it doesn't drift back: double-click on an internal
		// (non-leaf) row must change neither the tab count nor the dock topology.

		var window = AppComposition.Current.GetExport<MainWindow>();
		window.Show();
		var vm = (MainWindowViewModel)window.DataContext!;
		await vm.AssemblyTreeModel.WaitForAssembliesAsync(minimumCount: 1);

		var pane = await window.WaitForComponent<AssemblyListPane>();
		var grid = await pane.WaitForComponent<global::ILSpy.Controls.TreeView.SharpTreeView>();

		// Any realised SharpTreeViewItem whose data is an ILSpyTreeNode is a fine target; the
		// non-leaf assembly node row (depth 0) is always present and never confused with a
		// method row whose tree-toggle area is null.
		await Waiters.WaitForAsync(() => grid.GetVisualDescendants().OfType<global::ILSpy.Controls.TreeView.SharpTreeViewItem>()
			.Any(r => r.DataContext is ILSpyTreeNode));
		var row = grid.GetVisualDescendants().OfType<global::ILSpy.Controls.TreeView.SharpTreeViewItem>()
			.First(r => r.DataContext is ILSpyTreeNode);

		var documents = ((ILSpyDockFactory)vm.DockWorkspace.Factory).Documents!;
		int before = documents.VisibleDockables?.Count ?? 0;

		var topLevel = TopLevel.GetTopLevel(row)!;
		var rowBounds = row.Bounds;
		// Tree rows stretch to content width (with horizontal scroll), so clamp the click X to the
		// visible grid viewport — the row centre can sit off-screen past the grid's right edge.
		var centreInRow = new Point(System.Math.Min(rowBounds.Width, grid.Bounds.Width) / 2, rowBounds.Height / 2);
		var centreInTopLevel = row.TranslatePoint(centreInRow, topLevel)
			?? throw new System.InvalidOperationException("Row not in TopLevel visual tree");

		// Drive two LMB clicks at the same coordinate — Avalonia.Headless interprets the
		// second click within the double-click threshold as a real double-click event.
		topLevel.MouseDown(centreInTopLevel, MouseButton.Left);
		topLevel.MouseUp(centreInTopLevel, MouseButton.Left);
		topLevel.MouseDown(centreInTopLevel, MouseButton.Left);
		topLevel.MouseUp(centreInTopLevel, MouseButton.Left);

		// Give the decompile path a beat — if a tab is going to spawn, it will have queued by
		// now. (We can't `WaitForAsync` on "did NOT spawn", so wait a short fixed budget.)
		await Task.Delay(250);
		global::Avalonia.Threading.Dispatcher.UIThread.RunJobs();

		(documents.VisibleDockables?.Count ?? 0).Should().Be(before,
			"LMB double-click must not open a new tab — only MMB does");
	}
}