using System;
using Avalonia.Controls.Presenters;
using Avalonia.Controls.Templates;
using Avalonia.Controls.UnitTests.Utils;
using Avalonia.Data;
using Avalonia.Input;
using Avalonia.Interactivity;
using Avalonia.Layout;
using Avalonia.Media;
using Avalonia.Platform;
using Avalonia.Rendering;
using Avalonia.Threading;
using Avalonia.UnitTests;
using Moq;
using Xunit;
using MouseButton = Avalonia.Input.MouseButton;

namespace Avalonia.Controls.UnitTests
{
    public class ButtonTests : ScopedTestBase
    {
        private MouseTestHelper _helper = new MouseTestHelper();

        [Fact]
        public void Button_Is_Disabled_When_Command_Is_Disabled()
        {
            var command = new TestCommand(false);
            var target = new Button
            {
                Command = command,
            };
            var root = new TestRoot { Child = target };

            Assert.False(target.IsEffectivelyEnabled);
            command.IsEnabled = true;
            Assert.True(target.IsEffectivelyEnabled);
            command.IsEnabled = false;
            Assert.False(target.IsEffectivelyEnabled);
        }

        [Fact]
        public void Button_Is_Disabled_When_Command_Is_Enabled_But_IsEnabled_Is_False()
        {
            var command = new TestCommand(true);
            var target = new Button
            {
                IsEnabled = false,
                Command = command,
            };

            var root = new TestRoot { Child = target };

            Assert.False(((IInputElement)target).IsEffectivelyEnabled);
        }

        [Fact]
        public void Button_Is_Disabled_When_Bound_Command_Doesnt_Exist()
        {
            var target = new Button
            {
                [!Button.CommandProperty] = new Binding("Command"),
            };

            Assert.True(target.IsEnabled);
            Assert.False(target.IsEffectivelyEnabled);
        }

        [Fact]
        public void Button_Is_Disabled_When_Bound_Command_Is_Removed()
        {
            var viewModel = new
            {
                Command = new TestCommand(true),
            };

            var target = new Button
            {
                DataContext = viewModel,
                [!Button.CommandProperty] = new Binding("Command"),
            };

            Assert.True(target.IsEnabled);
            Assert.True(target.IsEffectivelyEnabled);

            target.DataContext = null;

            Assert.True(target.IsEnabled);
            Assert.False(target.IsEffectivelyEnabled);
        }

        [Fact]
        public void Button_Is_Enabled_When_Bound_Command_Is_Added()
        {
            var viewModel = new
            {
                Command = new TestCommand(true),
            };

            var target = new Button
            {
                DataContext = new object(),
                [!Button.CommandProperty] = new Binding("Command"),
            };
            var root = new TestRoot { Child = target };

            Dispatcher.UIThread.RunJobs(DispatcherPriority.Loaded);

            Assert.True(target.IsEnabled);
            Assert.False(target.IsEffectivelyEnabled);

            target.DataContext = viewModel;

            Assert.True(target.IsEnabled);
            Assert.True(target.IsEffectivelyEnabled);
        }

        [Fact]
        public void Button_Is_Disabled_When_Disabled_Bound_Command_Is_Added()
        {
            var viewModel = new
            {
                Command = new TestCommand(false),
            };

            var target = new Button
            {
                DataContext = new object(),
                [!Button.CommandProperty] = new Binding("Command"),
            };

            Assert.True(target.IsEnabled);
            Assert.False(target.IsEffectivelyEnabled);

            target.DataContext = viewModel;

            Assert.True(target.IsEnabled);
            Assert.False(target.IsEffectivelyEnabled);
        }

        [Fact]
        public void Button_Raises_Click()
        {
            var renderer = new Mock<IHitTester>();
            var pt = new Point(50, 50);
            renderer.Setup(r => r.HitTest(It.IsAny<Point>(), It.IsAny<Visual>(), It.IsAny<Func<Visual, bool>>()))
                .Returns<Point, Visual, Func<Visual, bool>>((p, r, f) =>
                    r.Bounds.Contains(p) ? new Visual[] { r } : new Visual[0]);

            using var _ = UnitTestApplication.Start(TestServices.StyledWindow);

            var root = new Window() { HitTesterOverride = renderer.Object };
            var target = new Button()
            {
                Width = 100,
                Height = 100,
                VerticalAlignment = VerticalAlignment.Top,
                HorizontalAlignment = HorizontalAlignment.Left
            };
            root.Content = target;
            root.Show();

            bool clicked = false;

            target.Click += (s, e) => clicked = true;

            RaisePointerEntered(target);
            RaisePointerMove(target, pt);
            RaisePointerPressed(target, 1, MouseButton.Left, pt);

            Assert.Equal(_helper.Captured, target);

            RaisePointerReleased(target, MouseButton.Left, pt);

            Assert.Equal(_helper.Captured, null);

            Assert.True(clicked);
        }

        [Fact]
        public void Button_Does_Not_Raise_Click_When_PointerReleased_Outside()
        {
            var root = new TestRoot();
            var target = new Button()
            {
                Width = 100,
                Height = 100
            };
            root.Child = target;

            bool clicked = false;

            target.Click += (s, e) => clicked = true;

            RaisePointerEntered(target);
            RaisePointerMove(target, new Point(50, 50));
            RaisePointerPressed(target, 1, MouseButton.Left, new Point(50, 50));
            RaisePointerExited(target);

            Assert.Equal(_helper.Captured, target);

            RaisePointerReleased(target, MouseButton.Left, new Point(200, 50));

            Assert.Equal(_helper.Captured, null);

            Assert.False(clicked);
        }

        [Fact]
        public void Button_With_RenderTransform_Raises_Click()
        {
            var renderer = new Mock<IHitTester>();
            var pt = new Point(150, 50);
            renderer.Setup(r => r.HitTest(It.IsAny<Point>(), It.IsAny<Visual>(), It.IsAny<Func<Visual, bool>>()))
                .Returns<Point, Visual, Func<Visual, bool>>((p, r, f) =>
                    r.Bounds.Contains(p.Transform(r.RenderTransform.Value.Invert())) ?
                    new Visual[] { r } : new Visual[0]);

            using var _ = UnitTestApplication.Start(TestServices.StyledWindow);

            var root = new Window() { HitTesterOverride = renderer.Object };
            var target = new Button()
            {
                Width = 100,
                Height = 100,
                VerticalAlignment = VerticalAlignment.Top,
                HorizontalAlignment = HorizontalAlignment.Left,
                RenderTransform = new TranslateTransform { X = 100, Y = 0 }
            };
            root.Content = target;
            root.Show();

            //actual bounds of button should  be 100,0,100,100 x -> translated 100 pixels
            //so mouse with x=150 coordinates should trigger click
            //button shouldn't count on bounds to calculate pointer is in the over or not, but
            //on avalonia event system, as renderer hit test will properly calculate whether to send
            //mouse over events to button based on rendered bounds
            //note: button also may have not rectangular shape and only renderer hit testing is reliable

            bool clicked = false;

            target.Click += (s, e) => clicked = true;

            RaisePointerEntered(target);
            RaisePointerMove(target, pt);
            RaisePointerPressed(target, 1, MouseButton.Left, pt);

            Assert.Equal(_helper.Captured, target);

            RaisePointerReleased(target, MouseButton.Left, pt);

            Assert.Equal(_helper.Captured, null);

            Assert.True(clicked);
        }

        [Fact]
        public void Button_Does_Not_Subscribe_To_Command_CanExecuteChanged_Until_Added_To_Logical_Tree()
        {
            var command = new TestCommand(true);
            var target = new Button
            {
                Command = command,
            };

            Assert.Equal(0, command.SubscriptionCount);
        }

        [Fact]
        public void Button_Subscribes_To_Command_CanExecuteChanged_When_Added_To_Logical_Tree()
        {
            var command = new TestCommand(true);
            var target = new Button { Command = command };
            var root = new TestRoot { Child = target };

            Assert.Equal(1, command.SubscriptionCount);
        }

        [Fact]
        public void Button_Unsubscribes_From_Command_CanExecuteChanged_When_Removed_From_Logical_Tree()
        {
            var command = new TestCommand(true);
            var target = new Button { Command = command };
            var root = new TestRoot { Child = target };

            root.Child = null;
            Assert.Equal(0, command.SubscriptionCount);
        }

        [Fact]
        public void Button_Invokes_CanExecute_When_CommandParameter_Changed()
        {
            var target = new Button();
            var raised = 0;

            target.Click += (s, e) => ++raised;
            
            target.RaiseEvent(new AccessKeyEventArgs("b", false));
            
            Assert.Equal(1, raised);
        }

        [Fact]
        public void Raises_Click_When_AccessKey_Raised()
        {
            var raised = 0;
            var ah = new AccessKeyHandler();
            var kd = new KeyboardDevice();
            using var app = UnitTestApplication.Start(TestServices.StyledWindow
                .With(
                    accessKeyHandler: ah, 
                    keyboardDevice: () => kd)
            );

            var impl = CreateMockTopLevelImpl();
            var command = new TestCommand(p => p is bool value && value, _ => raised++);

            Button target;
            var root = new TestTopLevel(impl.Object)
            {
                Template = CreateTemplate(),
                Content = target = new Button
                {
                    Content = "_A",
                    Command = command,
                    Template = new FuncControlTemplate<Button>((parent, scope) =>
                    {
                        return new ContentPresenter
                        {
                            Name = "PART_ContentPresenter",
                            [~ContentPresenter.ContentProperty] = new TemplateBinding(Button.ContentProperty),
                            [~ContentPresenter.ContentTemplateProperty] = new TemplateBinding(Button.ContentProperty),
                            RecognizesAccessKey = true,
                        }.RegisterInNameScope(scope);
                    })
                },
            };

            root.ApplyTemplate();
            root.Presenter.UpdateChild();
            target.ApplyTemplate();
            target.Presenter.UpdateChild();
            kd.SetFocusedElement(target, NavigationMethod.Unspecified, KeyModifiers.None);

            Dispatcher.UIThread.RunJobs(DispatcherPriority.Loaded);

            var accessKey = Key.A;
            target.CommandParameter = true;

            RaiseAccessKey(root, accessKey);

            Assert.Equal(1, raised);

            target.CommandParameter = false;

            RaiseAccessKey(root, accessKey);

            Assert.Equal(1, raised);
            
            static FuncControlTemplate<TestTopLevel> CreateTemplate()
            {
                return new FuncControlTemplate<TestTopLevel>((x, scope) =>
                    new ContentPresenter
                    {
                        Name = "PART_ContentPresenter",
                        [~ContentPresenter.ContentProperty] = new TemplateBinding(ContentControl.ContentProperty),
                        [~ContentPresenter.ContentTemplateProperty] = new TemplateBinding(ContentControl.ContentTemplateProperty)
                    }.RegisterInNameScope(scope));
            }

            static Mock<ITopLevelImpl> CreateMockTopLevelImpl(bool setupProperties = false)
            {
                var topLevel = new Mock<ITopLevelImpl>();
                if (setupProperties)
                    topLevel.SetupAllProperties();
                topLevel.Setup(x => x.RenderScaling).Returns(1);
                topLevel.Setup(x => x.Compositor).Returns(RendererMocks.CreateDummyCompositor());
                return topLevel;
            }

            static void RaiseAccessKey(IInputElement target, Key accessKey)
            {
                KeyDown(target, Key.LeftAlt);
                KeyDown(target, accessKey, KeyModifiers.Alt);
                KeyUp(target, accessKey, KeyModifiers.Alt);
                KeyUp(target, Key.LeftAlt);
            }

            static void KeyDown(IInputElement target, Key key, KeyModifiers modifiers = KeyModifiers.None)
            {
                target.RaiseEvent(new KeyEventArgs
                {
                    RoutedEvent = InputElement.KeyDownEvent,
                    Key = key,
                    KeyModifiers = modifiers,
                });
            }

            static void KeyUp(IInputElement target, Key key, KeyModifiers modifiers = KeyModifiers.None)
            {
                target.RaiseEvent(new KeyEventArgs
                {
                    RoutedEvent = InputElement.KeyUpEvent,
                    Key = key,
                    KeyModifiers = modifiers,
                });
            }
        }

        [Fact]
        public void Button_Invokes_Doesnt_Execute_When_Button_Disabled()
        {
            var target = new Button();
            var raised = 0;

            target.IsEnabled = false;
            target.Click += (s, e) => ++raised;

            target.RaiseEvent(new AccessKeyEventArgs("b", false));

            Assert.Equal(0, raised);
        }

        [Fact]
        public void Button_IsDefault_Works()
        {
            using (UnitTestApplication.Start(TestServices.StyledWindow))
            {
                var raised = 0;
                var target = new Button();
                var window = new Window { Content = target };
                window.Show();

                target.Click += (s, e) => ++raised;

                target.IsDefault = false;
                window.RaiseEvent(CreateKeyDownEvent(Key.Enter));
                Assert.Equal(0, raised);

                target.IsDefault = true;
                window.RaiseEvent(CreateKeyDownEvent(Key.Enter));
                Assert.Equal(1, raised);

                target.IsDefault = false;
                window.RaiseEvent(CreateKeyDownEvent(Key.Enter));
                Assert.Equal(1, raised);

                target.IsDefault = true;
                window.RaiseEvent(CreateKeyDownEvent(Key.Enter));
                Assert.Equal(2, raised);

                window.Content = null;
                // To check if handler was raised on the button, when it's detached, we need to pass it as a source manually.
                window.RaiseEvent(CreateKeyDownEvent(Key.Enter, target));
                Assert.Equal(2, raised);
            }
        }
        
        [Fact]
        public void Button_IsDefault_Should_Not_Work_When_Button_Is_Not_Effectively_Visible()
        {
            using (UnitTestApplication.Start(TestServices.StyledWindow))
            {
                var raised = 0;
                var panel = new Panel();
                var target = new Button();
                panel.Children.Add(target);
                var window = new Window { Content = panel };
                window.Show();

                target.Click += (s, e) => ++raised;
                
                target.IsDefault = true;
                panel.IsVisible = false;
                window.RaiseEvent(CreateKeyDownEvent(Key.Enter));
                Assert.Equal(0, raised);
            }
        }

        [Fact]
        public void Button_IsCancel_Works()
        {
            using (UnitTestApplication.Start(TestServices.StyledWindow))
            {
                var raised = 0;
                var target = new Button();
                var window = new Window { Content = target };
                window.Show();

                target.Click += (s, e) => ++raised;

                target.IsCancel = false;
                window.RaiseEvent(CreateKeyDownEvent(Key.Escape));
                Assert.Equal(0, raised);

                target.IsCancel = true;
                window.RaiseEvent(CreateKeyDownEvent(Key.Escape));
                Assert.Equal(1, raised);

                target.IsCancel = false;
                window.RaiseEvent(CreateKeyDownEvent(Key.Escape));
                Assert.Equal(1, raised);

                target.IsCancel = true;
                window.RaiseEvent(CreateKeyDownEvent(Key.Escape));
                Assert.Equal(2, raised);

                window.Content = null;
                window.RaiseEvent(CreateKeyDownEvent(Key.Escape, target));
                Assert.Equal(2, raised);
            }
        }
        
        [Fact]
        public void Button_IsCancel_Should_Not_Work_When_Button_Is_Not_Effectively_Visible()
        {
            using (UnitTestApplication.Start(TestServices.StyledWindow))
            {
                var raised = 0;
                var panel = new Panel();
                var target = new Button();
                panel.Children.Add(target);
                var window = new Window { Content = panel };
                window.Show();

                target.Click += (s, e) => ++raised;
                
                target.IsCancel = true;
                panel.IsVisible = false;
                window.RaiseEvent(CreateKeyDownEvent(Key.Escape));
                Assert.Equal(0, raised);
            }
        }

        [Fact]
        public void Button_CommandParameter_Does_Not_Change_While_Execution()
        {
            var target = new Button();
            object lastParamenter = "A";
            var generator = new Random();
            var onlyOnce = false;
            var command = new TestCommand(parameter =>
            {
                if (!onlyOnce)
                {
                    onlyOnce = true;
                    target.CommandParameter = generator.Next();
                }
                lastParamenter = parameter;
                return true;
            },
            parameter =>
            {
                Assert.Equal(lastParamenter, parameter);
            });
            target.CommandParameter = lastParamenter;
            target.Command = command;
            var root = new TestRoot { Child = target };

            (target as IClickableControl).RaiseClick();
        }

        [Fact]
        void Should_Not_Fire_Click_Event_On_Space_Key_When_It_Is_Not_Focus()
        {
            using (UnitTestApplication.Start(TestServices.StyledWindow))
            {
                var raised = 0;
                var target = new TextBox();
                var button = new Button()
                {
                    Content = target,
                };

                var window = new Window { Content = button };
                window.Show();

                button.Click += (s, e) => ++raised;
                target.Focus();
                target.RaiseEvent(CreateKeyDownEvent(Key.Space));
                target.RaiseEvent(CreateKeyUpEvent(Key.Space));
                Assert.Equal(0, raised);
            }
        }

        private KeyEventArgs CreateKeyDownEvent(Key key, Interactive source = null)
        {
            return new KeyEventArgs { RoutedEvent = InputElement.KeyDownEvent, Key = key, Source = source };
        }

        private KeyEventArgs CreateKeyUpEvent(Key key, Interactive source = null)
        {
            return new KeyEventArgs { RoutedEvent = InputElement.KeyUpEvent, Key = key, Source = source };
        }

        private void RaisePointerPressed(Button button, int clickCount, MouseButton mouseButton, Point position)
        {
            _helper.Down(button, mouseButton, position, clickCount: clickCount);
        }

        private void RaisePointerReleased(Button button, MouseButton mouseButton, Point pt)
        {
            _helper.Up(button, mouseButton, pt);
        }

        private void RaisePointerEntered(Button button)
        {
            _helper.Enter(button);
        }

        private void RaisePointerExited(Button button)
        {
            _helper.Leave(button);
        }

        private void RaisePointerMove(Button button, Point pos)
        {
            _helper.Move(button, pos);
        }



        private class TestTopLevel : TopLevel
        {
            private readonly ILayoutManager _layoutManager;
            public bool IsClosed { get; private set; }

            public TestTopLevel(ITopLevelImpl impl, ILayoutManager layoutManager = null)
                : base(impl)
            {
                _layoutManager = layoutManager ?? new LayoutManager(this);
            }

            private protected override ILayoutManager CreateLayoutManager() => _layoutManager;
        }
    }
}