// Copyright (c) The Avalonia Project. All rights reserved.
// Licensed under the MIT license. See licence.md file in the project root for full license information.

using Avalonia.Controls;
using Avalonia.Controls.Presenters;
using Avalonia.Layout;
using Avalonia.Media;
using Avalonia.Platform;
using Avalonia.Rendering;
using Avalonia.UnitTests;
using Moq;
using System;
using System.Collections.Generic;
using System.IO;
using Xunit;

namespace Avalonia.Input.UnitTests
{
    public class InputElement_HitTesting
    {
        [Fact]
        public void InputHitTest_Should_Find_Control_At_Point()
        {
            using (var application = UnitTestApplication.Start(new TestServices(renderInterface: new MockRenderInterface())))
            {
                var container = new Decorator
                {
                    Width = 200,
                    Height = 200,
                    Child = new Border
                    {
                        Width = 100,
                        Height = 100,
                        HorizontalAlignment = HorizontalAlignment.Center,
                        VerticalAlignment = VerticalAlignment.Center
                    }
                };

                container.Measure(Size.Infinity);
                container.Arrange(new Rect(container.DesiredSize));

                var context = new DrawingContext(Mock.Of<IDrawingContextImpl>());
                context.Render(container);

                var result = container.InputHitTest(new Point(100, 100));

                Assert.Equal(container.Child, result);
            }
        }

        [Fact]
        public void InputHitTest_Should_Not_Find_Control_Outside_Point()
        {
            using (UnitTestApplication.Start(new TestServices(renderInterface: new MockRenderInterface())))
            {
                var container = new Decorator
                {
                    Width = 200,
                    Height = 200,
                    Child = new Border
                    {
                        Width = 100,
                        Height = 100,
                        HorizontalAlignment = HorizontalAlignment.Center,
                        VerticalAlignment = VerticalAlignment.Center
                    }
                };

                container.Measure(Size.Infinity);
                container.Arrange(new Rect(container.DesiredSize));

                var context = new DrawingContext(Mock.Of<IDrawingContextImpl>());
                context.Render(container);

                var result = container.InputHitTest(new Point(10, 10));

                Assert.Equal(container, result);
            }
        }

        [Fact]
        public void InputHitTest_Should_Find_Top_Control_At_Point()
        {
            using (UnitTestApplication.Start(new TestServices(renderInterface: new MockRenderInterface())))
            {
                var container = new Panel
                {
                    Width = 200,
                    Height = 200,
                    Children = new Controls.Controls
                {
                    new Border
                    {
                        Width = 100,
                        Height = 100,
                        HorizontalAlignment = HorizontalAlignment.Center,
                        VerticalAlignment = VerticalAlignment.Center
                    },
                    new Border
                    {
                        Width = 50,
                        Height = 50,
                        HorizontalAlignment = HorizontalAlignment.Center,
                        VerticalAlignment = VerticalAlignment.Center
                    }
                }
                };

                container.Measure(Size.Infinity);
                container.Arrange(new Rect(container.DesiredSize));

                var context = new DrawingContext(Mock.Of<IDrawingContextImpl>());
                context.Render(container);

                var result = container.InputHitTest(new Point(100, 100));

                Assert.Equal(container.Children[1], result);
            }
        }

        [Fact]
        public void InputHitTest_Should_Find_Top_Control_At_Point_With_ZOrder()
        {
            using (UnitTestApplication.Start(new TestServices(renderInterface: new MockRenderInterface())))
            {
                var container = new Panel
                {
                    Width = 200,
                    Height = 200,
                    Children = new Controls.Controls
                {
                    new Border
                    {
                        Width = 100,
                        Height = 100,
                        ZIndex = 1,
                        HorizontalAlignment = HorizontalAlignment.Center,
                        VerticalAlignment = VerticalAlignment.Center
                    },
                    new Border
                    {
                        Width = 50,
                        Height = 50,
                        HorizontalAlignment = HorizontalAlignment.Center,
                        VerticalAlignment = VerticalAlignment.Center
                    }
                }
                };

                container.Measure(Size.Infinity);
                container.Arrange(new Rect(container.DesiredSize));

                var context = new DrawingContext(Mock.Of<IDrawingContextImpl>());
                context.Render(container);

                var result = container.InputHitTest(new Point(100, 100));

                Assert.Equal(container.Children[0], result);
            }
        }

        [Fact]
        public void InputHitTest_Should_Find_Control_Translated_Outside_Parent_Bounds()
        {
            using (UnitTestApplication.Start(new TestServices(renderInterface: new MockRenderInterface())))
            {
                Border target;
                var container = new Panel
                {
                    Width = 200,
                    Height = 200,
                    ClipToBounds = false,
                    Children = new Controls.Controls
                    {
                        new Border
                        {
                            Width = 100,
                            Height = 100,
                            ZIndex = 1,
                            HorizontalAlignment = HorizontalAlignment.Left,
                            VerticalAlignment = VerticalAlignment.Top,
                            Child = target = new Border
                            {
                                Width = 50,
                                Height = 50,
                                HorizontalAlignment = HorizontalAlignment.Left,
                                VerticalAlignment = VerticalAlignment.Top,
                                RenderTransform = new TranslateTransform(110, 110),
                            }
                        },
                    }
                };

                container.Measure(Size.Infinity);
                container.Arrange(new Rect(container.DesiredSize));

                var context = new DrawingContext(Mock.Of<IDrawingContextImpl>());
                context.Render(container);

                var result = container.InputHitTest(new Point(120, 120));

                Assert.Equal(target, result);
            }
        }

        [Fact]
        public void InputHitTest_Should_Not_Find_Control_Outside_Parent_Bounds_When_Clipped()
        {
            using (UnitTestApplication.Start(new TestServices(renderInterface: new MockRenderInterface())))
            {
                Border target;

                var container = new Panel
                {
                    Width = 100,
                    Height = 200,
                    Children = new Controls.Controls
                    {
                        new Panel()
                        {
                            Width = 100,
                            Height = 100,
                            Margin = new Thickness(0, 100, 0, 0),
                            ClipToBounds = true,
                            Children = new Controls.Controls
                            {
                                (target = new Border()
                                {
                                    Width = 100,
                                    Height = 100,
                                    Margin = new Thickness(0, -100, 0, 0)
                                })
                            }
                        }
                    }
                };

                container.Measure(Size.Infinity);
                container.Arrange(new Rect(container.DesiredSize));

                var context = new DrawingContext(Mock.Of<IDrawingContextImpl>());
                context.Render(container);

                var result = container.InputHitTest(new Point(50, 50));

                Assert.NotEqual(target, result);
                Assert.Equal(container, result);
            }
        }

        [Fact]
        public void InputHitTest_Should_Not_Find_Control_Outside_Scroll_ViewPort()
        {
            using (UnitTestApplication.Start(new TestServices(renderInterface: new MockRenderInterface())))
            {
                Border target;
                Border item1;
                Border item2;
                ScrollContentPresenter scroll;

                var container = new Panel
                {
                    Width = 100,
                    Height = 200,
                    Children = new Controls.Controls
                    {
                        (target = new Border()
                        {
                            Width = 100,
                            Height = 100
                        }),
                        new Border()
                        {
                            Width = 100,
                            Height = 100,
                            Margin = new Thickness(0, 100, 0, 0),
                            Child = scroll = new ScrollContentPresenter()
                            {
                                Content = new StackPanel()
                                {
                                    Children = new Controls.Controls
                                    {
                                        (item1 = new Border()
                                        {
                                            Width = 100,
                                            Height = 100,
                                        }),
                                        (item2 = new Border()
                                        {
                                            Width = 100,
                                            Height = 100,
                                        }),
                                    }
                                }
                            }
                        }
                    }
                };

                scroll.UpdateChild();

                container.Measure(Size.Infinity);
                container.Arrange(new Rect(container.DesiredSize));

                var context = new DrawingContext(Mock.Of<IDrawingContextImpl>());
                context.Render(container);

                var result = container.InputHitTest(new Point(50, 150));

                Assert.Equal(item1, result);

                result = container.InputHitTest(new Point(50, 50));

                Assert.Equal(target, result);

                scroll.Offset = new Vector(0, 100);

                //we don't have setup LayoutManager so we will make it manually
                scroll.Parent.InvalidateArrange();
                container.InvalidateArrange();

                container.Arrange(new Rect(container.DesiredSize));
                context.Render(container);

                result = container.InputHitTest(new Point(50, 150));

                Assert.Equal(item2, result);

                result = container.InputHitTest(new Point(50, 50));

                Assert.NotEqual(item1, result);
                Assert.Equal(target, result);
            }
        }

        class MockRenderInterface : IPlatformRenderInterface
        {
            public IFormattedTextImpl CreateFormattedText(string text, string fontFamilyName, double fontSize, FontStyle fontStyle, TextAlignment textAlignment, FontWeight fontWeight, TextWrapping wrapping)
            {
                throw new NotImplementedException();
            }

            public IRenderTarget CreateRenderTarget(IEnumerable<object> surfaces)
            {
                throw new NotImplementedException();
            }

            public IRenderTargetBitmapImpl CreateRenderTargetBitmap(int width, int height)
            {
                throw new NotImplementedException();
            }

            public IStreamGeometryImpl CreateStreamGeometry()
            {
                return new MockStreamGeometry();
            }

            public IBitmapImpl LoadBitmap(Stream stream)
            {
                throw new NotImplementedException();
            }

            public IBitmapImpl LoadBitmap(string fileName)
            {
                throw new NotImplementedException();
            }

            public IBitmapImpl LoadBitmap(PixelFormat format, IntPtr data, int width, int height, int stride)
            {
                throw new NotImplementedException();
            }

            public IWritableBitmapImpl CreateWritableBitmap(int width, int height, PixelFormat? fmt)
            {
                throw new NotImplementedException();
            }

            class MockStreamGeometry : Avalonia.Platform.IStreamGeometryImpl
            {
                private MockStreamGeometryContext _impl = new MockStreamGeometryContext();
                public Rect Bounds
                {
                    get
                    {
                        throw new NotImplementedException();
                    }
                }

                public Matrix Transform
                {
                    get
                    {
                        throw new NotImplementedException();
                    }

                    set
                    {
                        throw new NotImplementedException();
                    }
                }

                public IStreamGeometryImpl Clone()
                {
                    return this;
                }

                public bool FillContains(Point point)
                {
                    return _impl.FillContains(point);
                }

                public Rect GetRenderBounds(double strokeThickness)
                {
                    throw new NotImplementedException();
                }

                public IStreamGeometryContextImpl Open()
                {
                    return _impl;
                }

                class MockStreamGeometryContext : IStreamGeometryContextImpl
                {
                    private List<Point> points = new List<Point>();
                    public void ArcTo(Point point, Size size, double rotationAngle, bool isLargeArc, SweepDirection sweepDirection)
                    {
                        throw new NotImplementedException();
                    }

                    public void BeginFigure(Point startPoint, bool isFilled)
                    {
                        points.Add(startPoint);
                    }

                    public void CubicBezierTo(Point point1, Point point2, Point point3)
                    {
                        throw new NotImplementedException();
                    }

                    public void Dispose()
                    {
                    }

                    public void EndFigure(bool isClosed)
                    {
                    }

                    public void LineTo(Point point)
                    {
                        points.Add(point);
                    }

                    public void QuadraticBezierTo(Point control, Point endPoint)
                    {
                        throw new NotImplementedException();
                    }

                    public void SetFillRule(FillRule fillRule)
                    {
                    }

                    public bool FillContains(Point point)
                    {
                        // Use the algorithm from http://www.blackpawn.com/texts/pointinpoly/default.html
                        // to determine if the point is in the geometry (since it will always be convex in this situation)
                        for (int i = 0; i < points.Count; i++)
                        {
                            var a = points[i];
                            var b = points[(i + 1) % points.Count];
                            var c = points[(i + 2) % points.Count];

                            Vector v0 = c - a;
                            Vector v1 = b - a;
                            Vector v2 = point - a;

                            var dot00 = v0 * v0;
                            var dot01 = v0 * v1;
                            var dot02 = v0 * v2;
                            var dot11 = v1 * v1;
                            var dot12 = v1 * v2;


                            var invDenom = 1 / (dot00 * dot11 - dot01 * dot01);
                            var u = (dot11 * dot02 - dot01 * dot12) * invDenom;
                            var v = (dot00 * dot12 - dot01 * dot02) * invDenom;
                            if ((u >= 0) && (v >= 0) && (u + v < 1)) return true;
                        }
                        return false;
                    }
                }
            }
        }
    }
}