using System.Collections.Generic;
using System.Linq;
using System.Text;
using Xunit;
using Xunit.Abstractions;

namespace Terminal.Gui.ViewsTests;

public class TreeViewTests {

	readonly ITestOutputHelper _output;

	public TreeViewTests (ITestOutputHelper output) => _output = output;

	/// <summary>
	/// Tests that <see cref="TreeView.Expand(object)"/> and <see cref="TreeView.IsExpanded(object)"/> are consistent
	/// </summary>
	[Fact]
	public void IsExpanded_TrueAfterExpand ()
	{
		var tree = CreateTree (out var f, out _, out _);
		Assert.False (tree.IsExpanded (f));

		tree.Expand (f);
		Assert.True (tree.IsExpanded (f));

		tree.Collapse (f);
		Assert.False (tree.IsExpanded (f));
	}

	[Fact]
	public void EmptyTreeView_ContentSizes ()
	{
		var emptyTree = new TreeView ();
		Assert.Equal (0, emptyTree.ContentHeight);
		Assert.Equal (0, emptyTree.GetContentWidth (true));
		Assert.Equal (0, emptyTree.GetContentWidth (false));
	}

	[Fact]
	public void EmptyTreeViewGeneric_ContentSizes ()
	{
		var emptyTree = new TreeView<string> ();
		Assert.Equal (0, emptyTree.ContentHeight);
		Assert.Equal (0, emptyTree.GetContentWidth (true));
		Assert.Equal (0, emptyTree.GetContentWidth (false));
	}

	/// <summary>
	/// Tests that <see cref="TreeView.Expand(object)"/> results in a correct content height
	/// </summary>
	[Fact]
	public void ContentHeight_BiggerAfterExpand ()
	{
		var tree = CreateTree (out var f, out _, out _);
		Assert.Equal (1, tree.ContentHeight);

		tree.Expand (f);
		Assert.Equal (3, tree.ContentHeight);

		tree.Collapse (f);
		Assert.Equal (1, tree.ContentHeight);
	}

	[Fact]
	public void ContentWidth_BiggerAfterExpand ()
	{
		var tree = CreateTree (out var f, out var car1, out _);
		tree.BeginInit ();
		tree.EndInit ();

		tree.Bounds = new Rect (0, 0, 10, 10);

		InitFakeDriver ();

		//-+Factory
		Assert.Equal (9, tree.GetContentWidth (true));

		car1.Name = "123456789";

		tree.Expand (f);

		//..├-123456789
		Assert.Equal (13, tree.GetContentWidth (true));

		tree.Collapse (f);
		//-+Factory
		Assert.Equal (9, tree.GetContentWidth (true));

		Application.Shutdown ();
	}

	[Fact]
	public void ContentWidth_VisibleVsAll ()
	{
		var tree = CreateTree (out var f, out var car1, out var car2);
		tree.BeginInit ();
		tree.EndInit ();

		// control only allows 1 row to be viewed at once
		tree.Bounds = new Rect (0, 0, 20, 1);

		InitFakeDriver ();

		//-+Factory
		Assert.Equal (9, tree.GetContentWidth (true));
		Assert.Equal (9, tree.GetContentWidth (false));

		car1.Name = "123456789";
		car2.Name = "12345678";

		tree.Expand (f);

		// Although expanded the bigger (longer) child node is not in the rendered area of the control
		Assert.Equal (9, tree.GetContentWidth (true));
		Assert.Equal (13, tree.GetContentWidth (false)); // If you ask for the global max width it includes the longer child

		// Now that we have scrolled down 1 row we should see the big child
		tree.ScrollOffsetVertical = 1;
		Assert.Equal (13, tree.GetContentWidth (true));
		Assert.Equal (13, tree.GetContentWidth (false));

		// Scroll down so only car2 is visible
		tree.ScrollOffsetVertical = 2;
		Assert.Equal (12, tree.GetContentWidth (true));
		Assert.Equal (13, tree.GetContentWidth (false));

		// Scroll way down (off bottom of control even)
		tree.ScrollOffsetVertical = 5;
		Assert.Equal (0, tree.GetContentWidth (true));
		Assert.Equal (13, tree.GetContentWidth (false));

		Application.Shutdown ();
	}

	/// <summary>
	/// Tests that <see cref="TreeView.IsExpanded(object)"/> and <see cref="TreeView.Expand(object)"/> behaves correctly when
	/// an object cannot be expanded (because it has no children)
	/// </summary>
	[Fact]
	public void IsExpanded_FalseIfCannotExpand ()
	{
		var tree = CreateTree (out var f, out var c, out _);

		// expose the car by expanding the factory
		tree.Expand (f);

		// car is not expanded
		Assert.False (tree.IsExpanded (c));

		//try to expand the car (should have no effect because cars have no children)
		tree.Expand (c);

		Assert.False (tree.IsExpanded (c));

		// should also be ignored
		tree.Collapse (c);

		Assert.False (tree.IsExpanded (c));

		Application.Shutdown ();
	}

	/// <summary>
	/// Tests illegal ranges for <see cref="TreeView.ScrollOffset"/>
	/// </summary>
	[Fact]
	public void ScrollOffset_CannotBeNegative ()
	{
		var tree = CreateTree ();

		Assert.Equal (0, tree.ScrollOffsetVertical);

		tree.ScrollOffsetVertical = -100;
		Assert.Equal (0, tree.ScrollOffsetVertical);

		tree.ScrollOffsetVertical = 10;
		Assert.Equal (10, tree.ScrollOffsetVertical);
	}

	/// <summary>
	/// Tests <see cref="TreeView.GetScrollOffsetOf(object)"/> for objects that are as yet undiscovered by the tree
	/// </summary>
	[Fact]
	public void GetScrollOffsetOf_MinusOneForUnRevealed ()
	{
		var tree = CreateTree (out var f, out var c1, out var c2);

		// to start with the tree is collapsed and only knows about the root object
		Assert.Equal (0, tree.GetScrollOffsetOf (f));
		Assert.Equal (-1, tree.GetScrollOffsetOf (c1));
		Assert.Equal (-1, tree.GetScrollOffsetOf (c2));

		// reveal it by expanding the root object
		tree.Expand (f);

		// tree now knows about children
		Assert.Equal (0, tree.GetScrollOffsetOf (f));
		Assert.Equal (1, tree.GetScrollOffsetOf (c1));
		Assert.Equal (2, tree.GetScrollOffsetOf (c2));

		// after collapsing the root node again
		tree.Collapse (f);

		// tree no longer knows about the locations of these objects
		Assert.Equal (0, tree.GetScrollOffsetOf (f));
		Assert.Equal (-1, tree.GetScrollOffsetOf (c1));
		Assert.Equal (-1, tree.GetScrollOffsetOf (c2));
	}

	/// <summary>
	/// Simulates behind the scenes changes to an object (which children it has) and how to sync that into the tree using
	/// <see cref="TreeView.RefreshObject(object, bool)"/>
	/// </summary>
	[Fact]
	public void RefreshObject_ChildRemoved ()
	{
		var tree = CreateTree (out var f, out var c1, out var c2);

		//reveal it by expanding the root object
		tree.Expand (f);

		Assert.Equal (0, tree.GetScrollOffsetOf (f));
		Assert.Equal (1, tree.GetScrollOffsetOf (c1));
		Assert.Equal (2, tree.GetScrollOffsetOf (c2));

		// Factory now no longer makes Car c1 (only c2)
		f.Cars = new [] { c2 };

		// Tree does not know this yet
		Assert.Equal (0, tree.GetScrollOffsetOf (f));
		Assert.Equal (1, tree.GetScrollOffsetOf (c1));
		Assert.Equal (2, tree.GetScrollOffsetOf (c2));

		// If the user has selected the node c1
		tree.SelectedObject = c1;

		// When we refresh the tree
		tree.RefreshObject (f);

		// Now tree knows that factory has only one child node c2
		Assert.Equal (0, tree.GetScrollOffsetOf (f));
		Assert.Equal (-1, tree.GetScrollOffsetOf (c1));
		Assert.Equal (1, tree.GetScrollOffsetOf (c2));

		// The old selection was c1 which is now gone so selection should default to the parent of that branch (the factory)
		Assert.Equal (f, tree.SelectedObject);
	}

	/// <summary>
	/// Tests that <see cref="TreeView.GetParent(object)"/> returns the parent object for
	/// Cars (Factories).  Note that the method only works once the parent branch (Factory)
	/// is expanded to expose the child (Car)
	/// </summary>
	[Fact]
	public void GetParent_ReturnsParentOnlyWhenExpanded ()
	{
		var tree = CreateTree (out var f, out var c1, out var c2);

		Assert.Null (tree.GetParent (f));
		Assert.Null (tree.GetParent (c1));
		Assert.Null (tree.GetParent (c2));

		// now when we expand the factory we discover the cars
		tree.Expand (f);

		Assert.Null (tree.GetParent (f));
		Assert.Equal (f, tree.GetParent (c1));
		Assert.Equal (f, tree.GetParent (c2));

		tree.Collapse (f);

		Assert.Null (tree.GetParent (f));
		Assert.Null (tree.GetParent (c1));
		Assert.Null (tree.GetParent (c2));
	}

	/// <summary>
	/// Tests how the tree adapts to changes in the ChildrenGetter delegate during runtime
	/// when some branches are expanded and the new delegate returns children for a node that
	/// previously didn't have any children
	/// </summary>
	[Fact]
	public void RefreshObject_AfterChangingChildrenGetterDuringRuntime ()
	{
		var tree = CreateTree (out var f, out var c1, out var c2);

		var wheel = "Shiny Wheel";

		// Expand the Factory
		tree.Expand (f);

		// c1 cannot have children
		Assert.Equal (f, tree.GetParent (c1));

		// expanding it does nothing
		tree.Expand (c1);
		Assert.False (tree.IsExpanded (c1));

		// change the children getter so that now cars can have wheels
		tree.TreeBuilder = new DelegateTreeBuilder<object> (o =>
			// factories have cars
			o is Factory ? new object [] { c1, c2 }
				// cars have wheels
				: new object [] { wheel });

		// still cannot expand
		tree.Expand (c1);
		Assert.False (tree.IsExpanded (c1));

		tree.RefreshObject (c1);
		tree.Expand (c1);
		Assert.True (tree.IsExpanded (c1));
		Assert.Equal (wheel, tree.GetChildren (c1).FirstOrDefault ());
	}

	/// <summary>
	/// Same as <see cref="RefreshObject_AfterChangingChildrenGetterDuringRuntime"/> but
	/// uses <see cref="TreeView.RebuildTree()"/> instead of <see cref="TreeView.RefreshObject(object, bool)"/>
	/// </summary>
	[Fact]
	public void RebuildTree_AfterChangingChildrenGetterDuringRuntime ()
	{
		var tree = CreateTree (out var f, out var c1, out var c2);

		var wheel = "Shiny Wheel";

		// Expand the Factory
		tree.Expand (f);

		// c1 cannot have children
		Assert.Equal (f, tree.GetParent (c1));

		// expanding it does nothing
		tree.Expand (c1);
		Assert.False (tree.IsExpanded (c1));

		// change the children getter so that now cars can have wheels
		tree.TreeBuilder = new DelegateTreeBuilder<object> (o =>
			// factories have cars
			o is Factory ? new object [] { c1, c2 }
				// cars have wheels
				: new object [] { wheel });

		// still cannot expand
		tree.Expand (c1);
		Assert.False (tree.IsExpanded (c1));

		// Rebuild the tree
		tree.RebuildTree ();

		// Rebuild should not have collapsed any branches or done anything wierd
		Assert.True (tree.IsExpanded (f));

		tree.Expand (c1);
		Assert.True (tree.IsExpanded (c1));
		Assert.Equal (wheel, tree.GetChildren (c1).FirstOrDefault ());
	}

	/// <summary>
	/// Tests that <see cref="TreeView.GetChildren(object)"/> returns the child objects for
	/// the factory.  Note that the method only works once the parent branch (Factory)
	/// is expanded to expose the child (Car)
	/// </summary>
	[Fact]
	public void GetChildren_ReturnsChildrenOnlyWhenExpanded ()
	{
		var tree = CreateTree (out var f, out var c1, out var c2);

		Assert.Empty (tree.GetChildren (f));
		Assert.Empty (tree.GetChildren (c1));
		Assert.Empty (tree.GetChildren (c2));

		// now when we expand the factory we discover the cars
		tree.Expand (f);

		Assert.Contains (c1, tree.GetChildren (f));
		Assert.Contains (c2, tree.GetChildren (f));
		Assert.Empty (tree.GetChildren (c1));
		Assert.Empty (tree.GetChildren (c2));

		tree.Collapse (f);

		Assert.Empty (tree.GetChildren (f));
		Assert.Empty (tree.GetChildren (c1));
		Assert.Empty (tree.GetChildren (c2));
	}

	[Fact]
	public void TreeNode_WorksWithoutDelegate ()
	{
		var tree = new TreeView ();

		var root = new TreeNode ("Root");
		root.Children.Add (new TreeNode ("Leaf1"));
		root.Children.Add (new TreeNode ("Leaf2"));

		tree.AddObject (root);

		tree.Expand (root);
		Assert.Equal (2, tree.GetChildren (root).Count ());
	}

	[Fact]
	public void MultiSelect_GetAllSelectedObjects ()
	{
		var tree = new TreeView ();

		TreeNode l1;
		TreeNode l2;
		TreeNode l3;
		TreeNode l4;

		var root = new TreeNode ("Root");
		root.Children.Add (l1 = new TreeNode ("Leaf1"));
		root.Children.Add (l2 = new TreeNode ("Leaf2"));
		root.Children.Add (l3 = new TreeNode ("Leaf3"));
		root.Children.Add (l4 = new TreeNode ("Leaf4"));

		tree.AddObject (root);
		tree.MultiSelect = true;

		tree.Expand (root);
		Assert.Empty (tree.GetAllSelectedObjects ());

		tree.SelectedObject = root;

		Assert.Single (tree.GetAllSelectedObjects (), root);

		// move selection down 1
		tree.AdjustSelection (1);

		Assert.Single (tree.GetAllSelectedObjects (), l1);

		// expand selection down 2 (e.g. shift down twice)
		tree.AdjustSelection (1, true);
		tree.AdjustSelection (1, true);

		Assert.Equal (3, tree.GetAllSelectedObjects ().Count ());
		Assert.Contains (l1, tree.GetAllSelectedObjects ());
		Assert.Contains (l2, tree.GetAllSelectedObjects ());
		Assert.Contains (l3, tree.GetAllSelectedObjects ());

		tree.Collapse (root);

		// No selected objects since the root was collapsed
		Assert.Empty (tree.GetAllSelectedObjects ());
	}

	[Fact]
	public void ObjectActivated_Called ()
	{
		var tree = CreateTree (out var f, out var car1, out _);

		InitFakeDriver ();

		object activated = null;
		var called = false;

		// register for the event
		tree.ObjectActivated += (s, e) => {
			activated = e.ActivatedObject;
			called = true;
		};

		Assert.False (called);

		// no object is selected yet so no event should happen
		tree.NewKeyDownEvent (new Key (KeyCode.Enter));

		Assert.Null (activated);
		Assert.False (called);

		// down to select factory
		tree.NewKeyDownEvent (new Key (KeyCode.CursorDown));

		tree.NewKeyDownEvent (new Key (KeyCode.Enter));

		Assert.True (called);
		Assert.Same (f, activated);

		Application.Shutdown ();
	}

	[Fact]
	public void GoTo_OnlyAppliesToExposedObjects ()
	{
		var tree = CreateTree (out var f, out var car1, out _);
		tree.BeginInit ();
		tree.EndInit ();

		// Make tree bounds 1 in height so that EnsureVisible always requires updating scroll offset
		tree.Bounds = new Rect (0, 0, 50, 1);

		Assert.Null (tree.SelectedObject);
		Assert.Equal (0, tree.ScrollOffsetVertical);

		// car 1 is not yet exposed
		tree.GoTo (car1);

		Assert.Null (tree.SelectedObject);
		Assert.Equal (0, tree.ScrollOffsetVertical);

		tree.Expand (f);

		// Car1 is now exposed by expanding the factory
		tree.GoTo (car1);

		Assert.Equal (car1, tree.SelectedObject);
		Assert.Equal (1, tree.ScrollOffsetVertical);
	}

	[Fact]
	public void GoToEnd_ShouldNotFailOnEmptyTreeView ()
	{
		var tree = new TreeView ();

		var exception = Record.Exception (() => tree.GoToEnd ());

		Assert.Null (exception);
	}

	[Fact]
	public void ObjectActivated_CustomKey ()
	{
		var tree = CreateTree (out var f, out var car1, out _);

		InitFakeDriver ();

		tree.ObjectActivationKey = KeyCode.Delete;
		object activated = null;
		var called = false;

		// register for the event
		tree.ObjectActivated += (s, e) => {
			activated = e.ActivatedObject;
			called = true;
		};

		Assert.False (called);

		// no object is selected yet so no event should happen
		tree.NewKeyDownEvent (new Key (KeyCode.Enter));

		Assert.Null (activated);
		Assert.False (called);

		// down to select factory
		tree.NewKeyDownEvent (new Key (KeyCode.CursorDown));

		tree.NewKeyDownEvent (new Key (KeyCode.Enter));

		// Enter is not the activation key in this unit test
		Assert.Null (activated);
		Assert.False (called);

		// Delete is the activation key in this test so should result in activation occurring
		tree.NewKeyDownEvent (new Key (KeyCode.Delete));

		Assert.True (called);
		Assert.Same (f, activated);

		Application.Shutdown ();
	}

	[Fact]
	public void ObjectActivationButton_DoubleClick ()
	{
		var tree = CreateTree (out var f, out var car1, out _);

		InitFakeDriver ();

		object activated = null;
		var called = false;

		// register for the event
		tree.ObjectActivated += (s, e) => {
			activated = e.ActivatedObject;
			called = true;
		};

		Assert.False (called);

		// double click triggers activation
		tree.MouseEvent (new MouseEvent { Y = 0, Flags = MouseFlags.Button1DoubleClicked });

		Assert.True (called);
		Assert.Same (f, activated);
		Assert.Same (f, tree.SelectedObject);

		Application.Shutdown ();
	}

	[Fact]
	public void ObjectActivationButton_SetToNull ()
	{
		var tree = CreateTree (out var f, out var car1, out _);

		InitFakeDriver ();

		// disable activation
		tree.ObjectActivationButton = null;

		object activated = null;
		var called = false;

		// register for the event
		tree.ObjectActivated += (s, e) => {
			activated = e.ActivatedObject;
			called = true;
		};

		Assert.False (called);

		// double click does nothing because we changed button to null
		tree.MouseEvent (new MouseEvent { Y = 0, Flags = MouseFlags.Button1DoubleClicked });

		Assert.False (called);
		Assert.Null (activated);
		Assert.Null (tree.SelectedObject);

		Application.Shutdown ();
	}

	[Fact]
	public void ObjectActivationButton_RightClick ()
	{
		var tree = CreateTree (out var f, out var car1, out _);

		InitFakeDriver ();

		tree.ObjectActivationButton = MouseFlags.Button2Clicked;
		tree.ExpandAll ();

		object activated = null;
		var called = false;

		// register for the event
		tree.ObjectActivated += (s, e) => {
			activated = e.ActivatedObject;
			called = true;
		};

		Assert.False (called);

		// double click does nothing because we changed button binding to right click
		tree.MouseEvent (new MouseEvent { Y = 1, Flags = MouseFlags.Button1DoubleClicked });

		Assert.Null (activated);
		Assert.False (called);

		tree.MouseEvent (new MouseEvent { Y = 1, Flags = MouseFlags.Button2Clicked });

		Assert.True (called);
		Assert.Same (car1, activated);
		Assert.Same (car1, tree.SelectedObject);

		Application.Shutdown ();
	}


	/// <summary>
	/// Simulates behind the scenes changes to an object (which children it has) and how to sync that into the tree using
	/// <see cref="TreeView.RefreshObject(object, bool)"/>
	/// </summary>
	[Fact]
	public void RefreshObject_EqualityTest ()
	{
		var obj1 = new EqualityTestObject { Name = "Bob", Age = 1 };
		var obj2 = new EqualityTestObject { Name = "Bob", Age = 2 };
		;

		var root = "root";

		var tree = new TreeView<object> ();
		tree.TreeBuilder = new DelegateTreeBuilder<object> (s => ReferenceEquals (s, root) ? new object [] { obj1 } : null);
		tree.AddObject (root);

		// Tree is not expanded so the root has no children yet
		Assert.Empty (tree.GetChildren (root));

		tree.Expand (root);

		// now that the tree is expanded we should get our child returned
		Assert.Equal (1, tree.GetChildren (root).Count (child => ReferenceEquals (obj1, child)));

		// change the getter to return an Equal object (but not the same reference - obj2)
		tree.TreeBuilder = new DelegateTreeBuilder<object> (s => ReferenceEquals (s, root) ? new object [] { obj2 } : null);

		// tree has cached the knowledge of what children the root has so won't know about the change (we still get obj1)
		Assert.Equal (1, tree.GetChildren (root).Count (child => ReferenceEquals (obj1, child)));

		// now that we refresh the root we should get the new child reference (obj2)
		tree.RefreshObject (root);
		Assert.Equal (1, tree.GetChildren (root).Count (child => ReferenceEquals (obj2, child)));

	}

	[Fact, AutoInitShutdown]
	public void TestGetObjectOnRow ()
	{
		var tv = new TreeView { Width = 20, Height = 10 };
		tv.BeginInit ();
		tv.EndInit ();
		var n1 = new TreeNode ("normal");
		var n1_1 = new TreeNode ("pink");
		var n1_2 = new TreeNode ("normal");
		n1.Children.Add (n1_1);
		n1.Children.Add (n1_2);

		var n2 = new TreeNode ("pink");
		tv.AddObject (n1);
		tv.AddObject (n2);
		tv.Expand (n1);

		tv.ColorScheme = new ColorScheme ();
		tv.LayoutSubviews ();
		tv.Draw ();

		TestHelpers.AssertDriverContentsAre (
			@"├-normal
│ ├─pink
│ └─normal
└─pink
", _output);

		Assert.Same (n1, tv.GetObjectOnRow (0));
		Assert.Same (n1_1, tv.GetObjectOnRow (1));
		Assert.Same (n1_2, tv.GetObjectOnRow (2));
		Assert.Same (n2, tv.GetObjectOnRow (3));
		Assert.Null (tv.GetObjectOnRow (4));

		tv.Collapse (n1);

		tv.Draw ();

		TestHelpers.AssertDriverContentsAre (
			@"├+normal
└─pink
", _output);

		Assert.Same (n1, tv.GetObjectOnRow (0));
		Assert.Same (n2, tv.GetObjectOnRow (1));
		Assert.Null (tv.GetObjectOnRow (2));
		Assert.Null (tv.GetObjectOnRow (3));
		Assert.Null (tv.GetObjectOnRow (4));
	}

	[Fact, AutoInitShutdown]
	public void TestGetObjectRow ()
	{
		var tv = new TreeView { Width = 20, Height = 10 };

		var n1 = new TreeNode ("normal");
		var n1_1 = new TreeNode ("pink");
		var n1_2 = new TreeNode ("normal");
		n1.Children.Add (n1_1);
		n1.Children.Add (n1_2);

		var n2 = new TreeNode ("pink");
		tv.AddObject (n1);
		tv.AddObject (n2);
		tv.Expand (n1);

		tv.ColorScheme = new ColorScheme ();
		tv.LayoutSubviews ();
		tv.Draw ();

		TestHelpers.AssertDriverContentsAre (
			@"├-normal
│ ├─pink
│ └─normal
└─pink
", _output);

		Assert.Equal (0, tv.GetObjectRow (n1));
		Assert.Equal (1, tv.GetObjectRow (n1_1));
		Assert.Equal (2, tv.GetObjectRow (n1_2));
		Assert.Equal (3, tv.GetObjectRow (n2));

		tv.Collapse (n1);

		tv.LayoutSubviews ();
		tv.Draw ();

		TestHelpers.AssertDriverContentsAre (
			@"├+normal
└─pink
", _output);
		Assert.Equal (0, tv.GetObjectRow (n1));
		Assert.Null (tv.GetObjectRow (n1_1));
		Assert.Null (tv.GetObjectRow (n1_2));
		Assert.Equal (1, tv.GetObjectRow (n2));

		// scroll down 1
		tv.ScrollOffsetVertical = 1;

		tv.LayoutSubviews ();
		tv.Draw ();

		TestHelpers.AssertDriverContentsAre (
			@"└─pink
", _output);
		Assert.Equal (-1, tv.GetObjectRow (n1));
		Assert.Null (tv.GetObjectRow (n1_1));
		Assert.Null (tv.GetObjectRow (n1_2));
		Assert.Equal (0, tv.GetObjectRow (n2));
	}

	[Fact, AutoInitShutdown]
	public void TestTreeViewColor ()
	{
		var tv = new TreeView { Width = 20, Height = 10 };
		tv.BeginInit ();
		tv.EndInit ();
		var n1 = new TreeNode ("normal");
		var n1_1 = new TreeNode ("pink");
		var n1_2 = new TreeNode ("normal");
		n1.Children.Add (n1_1);
		n1.Children.Add (n1_2);

		var n2 = new TreeNode ("pink");
		tv.AddObject (n1);
		tv.AddObject (n2);
		tv.Expand (n1);

		tv.ColorScheme = new ColorScheme ();
		tv.LayoutSubviews ();
		tv.Draw ();

		// create a new color scheme
		var pink = new Attribute (Color.Magenta, Color.Black);
		var hotpink = new Attribute (Color.BrightMagenta, Color.Black);

		// Normal drawing of the tree view
		TestHelpers.AssertDriverContentsAre (@"
├-normal
│ ├─pink
│ └─normal
└─pink
", _output);
		// Should all be the same color
		TestHelpers.AssertDriverAttributesAre (@"
0000000000
0000000000
0000000000
0000000000
", Application.Driver, tv.ColorScheme.Normal, pink);

		var pinkScheme = new ColorScheme {
			Normal = pink,
			Focus = hotpink
		};

		// and a delegate that uses the pink color scheme 
		// for nodes "pink"
		tv.ColorGetter = n => n.Text.Equals ("pink") ? pinkScheme : null;

		// redraw now that the custom color
		// delegate is registered
		tv.Draw ();

		// Same text
		TestHelpers.AssertDriverContentsAre (@"
├-normal
│ ├─pink
│ └─normal
└─pink
", _output);
		// but now the item (only not lines) appear
		// in pink when they are the word "pink"
		TestHelpers.AssertDriverAttributesAre (@"
00000000
00001111
0000000000
001111
", Application.Driver, tv.ColorScheme.Normal, pink);
	}

	[Fact, AutoInitShutdown]
	public void TestBottomlessTreeView_MaxDepth_5 ()
	{
		var tv = new TreeView<string> { Width = 20, Height = 10 };

		tv.TreeBuilder = new DelegateTreeBuilder<string> (
			s => new [] { (int.Parse (s) + 1).ToString () }
		);

		tv.AddObject ("1");
		tv.ColorScheme = new ColorScheme ();

		tv.LayoutSubviews ();
		tv.Draw ();

		// Nothing expanded
		TestHelpers.AssertDriverContentsAre (
			@"└+1
", _output);
		tv.MaxDepth = 5;
		tv.ExpandAll ();

		tv.Draw ();

		// Normal drawing of the tree view
		TestHelpers.AssertDriverContentsAre (
			@"    
└-1
  └-2
    └-3
      └-4
        └-5
          └─6
", _output);
		Assert.False (tv.CanExpand ("6"));
		Assert.False (tv.IsExpanded ("6"));

		tv.Collapse ("6");

		Assert.False (tv.CanExpand ("6"));
		Assert.False (tv.IsExpanded ("6"));

		tv.Collapse ("5");

		Assert.True (tv.CanExpand ("5"));
		Assert.False (tv.IsExpanded ("5"));

		tv.Draw ();

		// Normal drawing of the tree view
		TestHelpers.AssertDriverContentsAre (
			@"    
└-1
  └-2
    └-3
      └-4
        └+5
", _output);
	}

	[Fact, AutoInitShutdown]
	public void TestBottomlessTreeView_MaxDepth_3 ()
	{
		var tv = new TreeView<string> { Width = 20, Height = 10 };

		tv.TreeBuilder = new DelegateTreeBuilder<string> (
			s => new [] { (int.Parse (s) + 1).ToString () }
		);

		tv.AddObject ("1");
		tv.ColorScheme = new ColorScheme ();

		tv.LayoutSubviews ();
		tv.Draw ();

		// Nothing expanded
		TestHelpers.AssertDriverContentsAre (
			@"└+1
", _output);
		tv.MaxDepth = 3;
		tv.ExpandAll ();
		tv.Draw ();

		// Normal drawing of the tree view
		TestHelpers.AssertDriverContentsAre (
			@"    
└-1
  └-2
    └-3
      └─4
", _output);
	}

	[Fact, AutoInitShutdown]
	public void TestTreeView_DrawLineEvent ()
	{
		var tv = new TreeView { Width = 20, Height = 10 };

		var eventArgs = new List<DrawTreeViewLineEventArgs<ITreeNode>> ();

		tv.DrawLine += (s, e) => {
			eventArgs.Add (e);
		};

		var n1 = new TreeNode ("root one");
		var n1_1 = new TreeNode ("leaf 1");
		var n1_2 = new TreeNode ("leaf 2");
		n1.Children.Add (n1_1);
		n1.Children.Add (n1_2);

		var n2 = new TreeNode ("root two");
		tv.AddObject (n1);
		tv.AddObject (n2);
		tv.Expand (n1);

		tv.ColorScheme = new ColorScheme ();
		tv.LayoutSubviews ();
		tv.Draw ();

		// Normal drawing of the tree view
		TestHelpers.AssertDriverContentsAre (
			@"
├-root one
│ ├─leaf 1
│ └─leaf 2
└─root two
", _output);
		Assert.Equal (4, eventArgs.Count ());

		Assert.Equal (0, eventArgs [0].Y);
		Assert.Equal (1, eventArgs [1].Y);
		Assert.Equal (2, eventArgs [2].Y);
		Assert.Equal (3, eventArgs [3].Y);

		Assert.All (eventArgs, ea => Assert.Equal (ea.Tree, tv));
		Assert.All (eventArgs, ea => Assert.False (ea.Handled));

		Assert.Equal ("├-root one", eventArgs [0].RuneCells.Aggregate ("", (s, n) => s += n.Rune).TrimEnd ());
		Assert.Equal ("│ ├─leaf 1", eventArgs [1].RuneCells.Aggregate ("", (s, n) => s += n.Rune).TrimEnd ());
		Assert.Equal ("│ └─leaf 2", eventArgs [2].RuneCells.Aggregate ("", (s, n) => s += n.Rune).TrimEnd ());
		Assert.Equal ("└─root two", eventArgs [3].RuneCells.Aggregate ("", (s, n) => s += n.Rune).TrimEnd ());

		Assert.Equal (1, eventArgs [0].IndexOfExpandCollapseSymbol);
		Assert.Equal (3, eventArgs [1].IndexOfExpandCollapseSymbol);
		Assert.Equal (3, eventArgs [2].IndexOfExpandCollapseSymbol);
		Assert.Equal (1, eventArgs [3].IndexOfExpandCollapseSymbol);

		Assert.Equal (2, eventArgs [0].IndexOfModelText);
		Assert.Equal (4, eventArgs [1].IndexOfModelText);
		Assert.Equal (4, eventArgs [2].IndexOfModelText);
		Assert.Equal (2, eventArgs [3].IndexOfModelText);


		Assert.Equal ("root one", eventArgs [0].Model.Text);
		Assert.Equal ("leaf 1", eventArgs [1].Model.Text);
		Assert.Equal ("leaf 2", eventArgs [2].Model.Text);
		Assert.Equal ("root two", eventArgs [3].Model.Text);
	}

	[Fact, AutoInitShutdown]
	public void TestTreeView_DrawLineEvent_WithScrolling ()
	{
		var tv = new TreeView { Width = 20, Height = 10 };

		var eventArgs = new List<DrawTreeViewLineEventArgs<ITreeNode>> ();

		tv.DrawLine += (s, e) => {
			eventArgs.Add (e);
		};

		tv.ScrollOffsetHorizontal = 3;
		tv.ScrollOffsetVertical = 1;

		var n1 = new TreeNode ("root one");
		var n1_1 = new TreeNode ("leaf 1");
		var n1_2 = new TreeNode ("leaf 2");
		n1.Children.Add (n1_1);
		n1.Children.Add (n1_2);

		var n2 = new TreeNode ("root two");
		tv.AddObject (n1);
		tv.AddObject (n2);
		tv.Expand (n1);

		tv.ColorScheme = new ColorScheme ();
		tv.LayoutSubviews ();
		tv.Draw ();

		// Normal drawing of the tree view
		TestHelpers.AssertDriverContentsAre (
			@"
─leaf 1
─leaf 2
oot two
", _output);
		Assert.Equal (3, eventArgs.Count ());

		Assert.Equal (0, eventArgs [0].Y);
		Assert.Equal (1, eventArgs [1].Y);
		Assert.Equal (2, eventArgs [2].Y);

		Assert.All (eventArgs, ea => Assert.Equal (ea.Tree, tv));
		Assert.All (eventArgs, ea => Assert.False (ea.Handled));

		Assert.Equal ("─leaf 1", eventArgs [0].RuneCells.Aggregate ("", (s, n) => s += n.Rune).TrimEnd ());
		Assert.Equal ("─leaf 2", eventArgs [1].RuneCells.Aggregate ("", (s, n) => s += n.Rune).TrimEnd ());
		Assert.Equal ("oot two", eventArgs [2].RuneCells.Aggregate ("", (s, n) => s += n.Rune).TrimEnd ());

		Assert.Equal (0, eventArgs [0].IndexOfExpandCollapseSymbol);
		Assert.Equal (0, eventArgs [1].IndexOfExpandCollapseSymbol);
		Assert.Null (eventArgs [2].IndexOfExpandCollapseSymbol);

		Assert.Equal (1, eventArgs [0].IndexOfModelText);
		Assert.Equal (1, eventArgs [1].IndexOfModelText);
		Assert.Equal (-1, eventArgs [2].IndexOfModelText);

		Assert.Equal ("leaf 1", eventArgs [0].Model.Text);
		Assert.Equal ("leaf 2", eventArgs [1].Model.Text);
		Assert.Equal ("root two", eventArgs [2].Model.Text);
	}

	[Fact, AutoInitShutdown]
	public void TestTreeView_DrawLineEvent_Handled ()
	{
		var tv = new TreeView { Width = 20, Height = 10 };

		tv.DrawLine += (s, e) => {
			if (e.Model.Text.Equals ("leaf 1")) {
				e.Handled = true;

				for (var i = 0; i < 10; i++) {

					e.Tree.AddRune (i, e.Y, new Rune ('F'));
				}
			}
		};

		var n1 = new TreeNode ("root one");
		var n1_1 = new TreeNode ("leaf 1");
		var n1_2 = new TreeNode ("leaf 2");
		n1.Children.Add (n1_1);
		n1.Children.Add (n1_2);

		var n2 = new TreeNode ("root two");
		tv.AddObject (n1);
		tv.AddObject (n2);
		tv.Expand (n1);

		tv.ColorScheme = new ColorScheme ();
		tv.LayoutSubviews ();
		tv.Draw ();

		// Normal drawing of the tree view
		TestHelpers.AssertDriverContentsAre (
			@"
├-root one
FFFFFFFFFF
│ └─leaf 2
└─root two
", _output);
	}

	[Fact, AutoInitShutdown]
	public void TestTreeView_Filter ()
	{
		var tv = new TreeView { Width = 20, Height = 10 };

		var n1 = new TreeNode ("root one");
		var n1_1 = new TreeNode ("leaf 1");
		var n1_2 = new TreeNode ("leaf 2");
		n1.Children.Add (n1_1);
		n1.Children.Add (n1_2);

		var n2 = new TreeNode ("root two");
		tv.AddObject (n1);
		tv.AddObject (n2);
		tv.Expand (n1);

		tv.ColorScheme = new ColorScheme ();
		tv.LayoutSubviews ();
		tv.Draw ();

		// Normal drawing of the tree view
		TestHelpers.AssertDriverContentsAre (
			@"
├-root one
│ ├─leaf 1
│ └─leaf 2
└─root two
", _output);
		var filter = new TreeViewTextFilter<ITreeNode> (tv);
		tv.Filter = filter;

		// matches nothing
		filter.Text = "asdfjhasdf";
		tv.Draw ();
		// Normal drawing of the tree view
		TestHelpers.AssertDriverContentsAre (
			@"", _output);


		// Matches everything
		filter.Text = "root";
		tv.Draw ();
		TestHelpers.AssertDriverContentsAre (
			@"
├-root one
│ ├─leaf 1
│ └─leaf 2
└─root two
", _output);
		// Matches 2 leaf nodes
		filter.Text = "leaf";
		tv.Draw ();
		TestHelpers.AssertDriverContentsAre (
			@"
├-root one
│ ├─leaf 1
│ └─leaf 2
", _output);

		// Matches 1 leaf nodes
		filter.Text = "leaf 1";
		tv.Draw ();
		TestHelpers.AssertDriverContentsAre (
			@"
├-root one
│ ├─leaf 1
", _output);
	}

	[Fact, AutoInitShutdown]
	public void DesiredCursorVisibility_MultiSelect ()
	{
		var tv = new TreeView { Width = 20, Height = 10 };

		var n1 = new TreeNode ("normal");
		var n2 = new TreeNode ("pink");
		tv.AddObject (n1);
		tv.AddObject (n2);

		Application.Top.Add (tv);
		Application.Begin (Application.Top);

		Assert.True (tv.MultiSelect);
		Assert.True (tv.HasFocus);
		Assert.Equal (CursorVisibility.Invisible, tv.DesiredCursorVisibility);

		tv.SelectAll ();
		tv.DesiredCursorVisibility = CursorVisibility.Default;
		Application.Refresh ();
		Application.Driver.GetCursorVisibility (out var visibility);
		Assert.Equal (CursorVisibility.Default, tv.DesiredCursorVisibility);
		Assert.Equal (CursorVisibility.Default, visibility);
	}

	void InitFakeDriver ()
	{
		var driver = new FakeDriver ();
		Application.Init (driver);
		driver.Init ();
	}

	/// <summary>
	/// Test object which considers for equality only <see cref="Name"/>
	/// </summary>
	class EqualityTestObject {
		public string Name { get; set; }

		public int Age { get; set; }

		public override int GetHashCode () => Name?.GetHashCode () ?? base.GetHashCode ();

		public override bool Equals (object obj) => obj is EqualityTestObject eto && Equals (Name, eto.Name);
	}

	#region Test Setup Methods
	class Factory {
		public Car [] Cars { get; set; }

		public override string ToString () => "Factory";
	}

	class Car {
		public string Name { get; set; }

		public override string ToString () => Name;
	}

	TreeView<object> CreateTree () => CreateTree (out _, out _, out _);

	TreeView<object> CreateTree (out Factory factory1, out Car car1, out Car car2)
	{
		car1 = new Car ();
		car2 = new Car ();

		factory1 = new Factory {
			Cars = new [] { car1, car2 }
		};

		var tree = new TreeView<object> (new DelegateTreeBuilder<object> (s => s is Factory f ? f.Cars : null));
		tree.AddObject (factory1);

		return tree;
	}
	#endregion
}