using System;
using System.Threading.Tasks;
using Avalonia.Animation;
using Avalonia.Controls;
using Avalonia.Styling;
using Xunit;
using Avalonia.Animation.Easings;
using System.Threading;
using System.Reactive.Linq;
using Avalonia.Layout;

namespace Avalonia.Base.UnitTests.Animation
{
    using Animation = Avalonia.Animation.Animation;

    public class AnimationIterationTests
    {
        [Fact]
        public void Check_KeyTime_Correctly_Converted_To_Cue()
        {
            var keyframe1 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 100d), }, KeyTime = TimeSpan.FromSeconds(0.5)
            };

            var keyframe2 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 0d), }, KeyTime = TimeSpan.FromSeconds(0)
            };

            var animation = new Animation() { Duration = TimeSpan.FromSeconds(1), Children = { keyframe2, keyframe1 } };

            var border = new Border() { Height = 100d, Width = 100d };

            var clock = new TestClock();

            animation.RunAsync(border, clock);

            clock.Step(TimeSpan.Zero);
            Assert.Equal(border.Width, 0d);

            clock.Step(TimeSpan.FromSeconds(1));
            Assert.Equal(border.Width, 100d);
        }


        [Fact]
        public void Check_Initial_Inter_and_Trailing_Delay_Values()
        {
            var keyframe1 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 200d), }, Cue = new Cue(1d)
            };

            var keyframe2 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 100d), }, Cue = new Cue(0d)
            };

            var animation = new Animation()
            {
                Duration = TimeSpan.FromSeconds(3),
                Delay = TimeSpan.FromSeconds(3),
                DelayBetweenIterations = TimeSpan.FromSeconds(3),
                IterationCount = new IterationCount(2),
                Children = { keyframe2, keyframe1 }
            };

            var border = new Border() { Height = 100d, Width = 100d };

            var clock = new TestClock();
            var animationRun = animation.RunAsync(border, clock);

            border.Measure(Size.Infinity);
            border.Arrange(new Rect(border.DesiredSize));
            
            clock.Step(TimeSpan.Zero);

            // Initial Delay.
            clock.Step(TimeSpan.FromSeconds(0));
            Assert.Equal(100d, border.Width);

            clock.Step(TimeSpan.FromSeconds(6));

            // First Inter-Iteration delay.
            clock.Step(TimeSpan.FromSeconds(8));
            Assert.Equal(border.Width, 200d);

            // Trailing Delay should be non-existent.
            clock.Step(TimeSpan.FromSeconds(14));
            Assert.True(animationRun.Status == TaskStatus.RanToCompletion);
            Assert.Equal(border.Width, 100d);
        }

        [Fact]
        public void Check_FillModes_Start_and_End_Values_if_Retained()
        {
            var keyframe1 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 0d), }, Cue = new Cue(0.0d)
            };

            var keyframe2 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 300d), }, Cue = new Cue(1.0d)
            };

            var animation = new Animation()
            {
                Duration = TimeSpan.FromSeconds(0.05d),
                Delay = TimeSpan.FromSeconds(0.05d),
                Easing = new SineEaseInOut(),
                FillMode = FillMode.Both,
                Children = { keyframe1, keyframe2 }
            };

            var border = new Border() { Height = 100d, Width = 100d, };

            var clock = new TestClock();

            animation.RunAsync(border, clock);

            clock.Step(TimeSpan.FromSeconds(0d));
            Assert.Equal(border.Width, 0d);

            clock.Step(TimeSpan.FromSeconds(0.050d));
            Assert.Equal(border.Width, 0d);

            clock.Step(TimeSpan.FromSeconds(0.100d));
            Assert.Equal(border.Width, 300d);
        }
        
        [Theory]
        [InlineData(FillMode.Backward, 50.0, 0.0, 0.7, false)]
        [InlineData(FillMode.Backward, 50.0, 0.0, 0.7, true )]
        [InlineData(FillMode.Both,     50.0, 0.0, 0.7, false)]
        [InlineData(FillMode.Both,     50.0, 0.0, 0.7, true )]
        [InlineData(FillMode.Forward,  50.0, 0.0, 0.7, false)] // no delay but cue 0.0: the animation has started normally, explaining the 50.0 target without fill
        [InlineData(FillMode.Forward, 100.0, 0.0, 0.7, true )]
        [InlineData(FillMode.Backward, 50.0, 0.3, 0.7, false)]
        [InlineData(FillMode.Backward, 50.0, 0.3, 0.7, true )]
        [InlineData(FillMode.Both,     50.0, 0.3, 0.7, false)]
        [InlineData(FillMode.Both,     50.0, 0.3, 0.7, true )]
        [InlineData(FillMode.Forward, 100.0, 0.3, 0.7, false)]
        [InlineData(FillMode.Forward, 100.0, 0.3, 0.7, true )]
        public void Check_FillMode_Start_Value(FillMode fillMode, double target, double startCue, double endCue, bool delay)
        {
            var keyframe1 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 50d), }, Cue = new Cue(startCue)
            };

            var keyframe2 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 300d), }, Cue = new Cue(endCue)
            };

            var animation = new Animation()
            {
                Duration = TimeSpan.FromSeconds(10d),
                Delay = delay ? TimeSpan.FromSeconds(5d) : TimeSpan.Zero,
                FillMode = fillMode,
                Children = { keyframe1, keyframe2 }
            };

            var border = new Border() { Height = 100d, Width = 100d, };
            
            var clock = new TestClock();
            
            animation.RunAsync(border, clock);
            
            clock.Step(TimeSpan.Zero);
            
            Assert.Equal(target, border.Width);
        }
        
        [Theory]
        [InlineData(FillMode.Backward, 100.0, 0.3, 1.0, false)]
        [InlineData(FillMode.Backward, 100.0, 0.3, 1.0, true )]
        [InlineData(FillMode.Both,     300.0, 0.3, 1.0, false)]
        [InlineData(FillMode.Both,     300.0, 0.3, 1.0, true )]
        [InlineData(FillMode.Forward,  300.0, 0.3, 1.0, false)]
        [InlineData(FillMode.Forward,  300.0, 0.3, 1.0, true )]
        [InlineData(FillMode.Backward, 100.0, 0.3, 0.7, false)]
        [InlineData(FillMode.Backward, 100.0, 0.3, 0.7, true )]
        [InlineData(FillMode.Both,     300.0, 0.3, 0.7, false)]
        [InlineData(FillMode.Both,     300.0, 0.3, 0.7, true )]
        [InlineData(FillMode.Forward,  300.0, 0.3, 0.7, false)]
        [InlineData(FillMode.Forward,  300.0, 0.3, 0.7, true )]
        public void Check_FillMode_End_Value(FillMode fillMode, double target, double startCue, double endCue, bool delay)
        {
            var keyframe1 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 0d), }, Cue = new Cue(startCue)
            };

            var keyframe2 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 300d), }, Cue = new Cue(endCue)
            };

            var animation = new Animation()
            {
                Duration = TimeSpan.FromSeconds(10d),
                Delay = delay ? TimeSpan.FromSeconds(5d) : TimeSpan.Zero,
                FillMode = fillMode,
                Children = { keyframe1, keyframe2 }
            };

            var border = new Border() { Height = 100d, Width = 100d, };
            
            var clock = new TestClock();
            
            animation.RunAsync(border, clock);
            
            clock.Step(TimeSpan.FromSeconds(0));
            clock.Step(TimeSpan.FromSeconds(20));
            
            Assert.Equal(target, border.Width);
        }
        
        [Fact]
        public void Dispose_Subscription_Should_Stop_Animation()
        {
            var keyframe1 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 200d), }, Cue = new Cue(1d)
            };

            var keyframe2 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 100d), }, Cue = new Cue(0d)
            };

            var animation = new Animation()
            {
                Duration = TimeSpan.FromSeconds(10),
                Delay = TimeSpan.FromSeconds(0),
                DelayBetweenIterations = TimeSpan.FromSeconds(0),
                IterationCount = new IterationCount(1),
                Children = { keyframe2, keyframe1 }
            };

            var border = new Border() { Height = 100d, Width = 50d };
            var propertyChangedCount = 0;
            var animationCompletedCount = 0;
            border.PropertyChanged += (_, e) =>
            {
                if (e.Property == Layoutable.WidthProperty)
                {
                    propertyChangedCount++;
                }
            };

            var clock = new TestClock();
            var disposable = animation.Apply(border, clock, Observable.Return(true), () => animationCompletedCount++);

            Assert.Equal(0, propertyChangedCount);

            clock.Step(TimeSpan.FromSeconds(0));
            Assert.Equal(0, animationCompletedCount);
            Assert.Equal(1, propertyChangedCount);

            disposable.Dispose();

            // Clock ticks should be ignored after Dispose
            clock.Step(TimeSpan.FromSeconds(5));
            clock.Step(TimeSpan.FromSeconds(6));
            clock.Step(TimeSpan.FromSeconds(7));

            // On animation disposing (cancellation) on completed is not invoked (is it expected?)
            Assert.Equal(0, animationCompletedCount);
            // Initial property changed before cancellation + animation value removal.
            Assert.Equal(2, propertyChangedCount);
        }

        [Fact]
        public void Do_Not_Run_Cancelled_Animation()
        {
            var keyframe1 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 200d), }, Cue = new Cue(1d)
            };

            var keyframe2 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 100d), }, Cue = new Cue(0d)
            };

            var animation = new Animation()
            {
                Duration = TimeSpan.FromSeconds(10),
                Delay = TimeSpan.FromSeconds(0),
                DelayBetweenIterations = TimeSpan.FromSeconds(0),
                IterationCount = new IterationCount(1),
                Children = { keyframe2, keyframe1 }
            };

            var border = new Border() { Height = 100d, Width = 100d };
            var propertyChangedCount = 0;
            border.PropertyChanged += (_, e) =>
            {
                if (e.Property == Layoutable.WidthProperty)
                {
                    propertyChangedCount++;
                }
            };

            var clock = new TestClock();
            var cancellationTokenSource = new CancellationTokenSource();
            cancellationTokenSource.Cancel();
            var animationRun = animation.RunAsync(border, clock, cancellationTokenSource.Token);

            clock.Step(TimeSpan.FromSeconds(10));
            Assert.Equal(0, propertyChangedCount);
            Assert.True(animationRun.IsCompleted);
        }

        [Fact]
        public async Task Cancellation_Should_Stop_Animation()
        {
            var keyframe1 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 200d), }, Cue = new Cue(1d)
            };

            var keyframe2 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 100d), }, Cue = new Cue(0d)
            };

            var animation = new Animation()
            {
                Duration = TimeSpan.FromSeconds(10),
                Delay = TimeSpan.FromSeconds(0),
                DelayBetweenIterations = TimeSpan.FromSeconds(0),
                IterationCount = new IterationCount(1),
                Children = { keyframe2, keyframe1 }
            };

            var border = new Border() { Height = 100d, Width = 50d };
            var propertyChangedCount = 0;
            border.PropertyChanged += (_, e) =>
            {
                if (e.Property == Layoutable.WidthProperty)
                {
                    propertyChangedCount++;
                }
            };

            var clock = new TestClock();
            var cancellationTokenSource = new CancellationTokenSource();
            var animationRun = animation.RunAsync(border, clock, cancellationTokenSource.Token);
            Assert.False(animationRun.IsCompleted);

            Assert.Equal(0, propertyChangedCount);

            clock.Step(TimeSpan.FromSeconds(0));
            Assert.False(animationRun.IsCompleted);
            Assert.Equal(1, propertyChangedCount);

            cancellationTokenSource.Cancel();
            clock.Step(TimeSpan.FromSeconds(1));
            clock.Step(TimeSpan.FromSeconds(2));
            clock.Step(TimeSpan.FromSeconds(3));

            await animationRun;

            clock.Step(TimeSpan.FromSeconds(6));
            Assert.True(animationRun.IsCompleted);
            Assert.Equal(2, propertyChangedCount);
        }

        [Fact]
        public void Dont_Run_Infinite_Iteration_Animation_On_RunAsync_Method()
        {
            var keyframe1 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 200d), }, Cue = new Cue(1d)
            };

            var keyframe2 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 100d), }, Cue = new Cue(0d)
            };

            var animation = new Animation()
            {
                Duration = TimeSpan.FromSeconds(10),
                Delay = TimeSpan.FromSeconds(0),
                DelayBetweenIterations = TimeSpan.FromSeconds(0),
                IterationCount = IterationCount.Infinite,
                Children = { keyframe2, keyframe1 }
            };

            var border = new Border() { Height = 100d, Width = 50d };
            var clock = new TestClock();
            var cancellationTokenSource = new CancellationTokenSource();
            var animationRun = animation.RunAsync(border, clock, cancellationTokenSource.Token);


            Assert.True(animationRun.IsCompleted);
            Assert.NotNull(animationRun.Exception);
        }

        [Fact]
        public async Task Cancellation_Of_Completed_Animation_Does_Not_Fail()
        {
            var keyframe1 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 200d), }, Cue = new Cue(1d)
            };

            var keyframe2 = new KeyFrame()
            {
                Setters = { new Setter(Layoutable.WidthProperty, 100d), }, Cue = new Cue(0d)
            };

            var animation = new Animation()
            {
                Duration = TimeSpan.FromSeconds(10),
                Delay = TimeSpan.FromSeconds(0),
                DelayBetweenIterations = TimeSpan.FromSeconds(0),
                IterationCount = new IterationCount(1),
                Children = { keyframe2, keyframe1 }
            };

            var border = new Border() { Height = 100d, Width = 50d };
            var propertyChangedCount = 0;
            border.PropertyChanged += (_, e) =>
            {
                if (e.Property == Layoutable.WidthProperty)
                {
                    propertyChangedCount++;
                }
            };

            var clock = new TestClock();
            var cancellationTokenSource = new CancellationTokenSource();
            var animationRun = animation.RunAsync(border, clock, cancellationTokenSource.Token);

            Assert.Equal(0, propertyChangedCount);

            clock.Step(TimeSpan.FromSeconds(0));
            Assert.False(animationRun.IsCompleted);
            Assert.Equal(1, propertyChangedCount);

            clock.Step(TimeSpan.FromSeconds(10));
            Assert.True(animationRun.IsCompleted);
            Assert.Equal(2, propertyChangedCount);

            cancellationTokenSource.Cancel();
            await animationRun;
        }

        // https://github.com/AvaloniaUI/Avalonia/issues/12582
        [Fact]
        public async Task Interpolator_Is_Not_Called_After_Last_Iteration()
        {
            var animator = new FakeAnimator();

            Setter CreateWidthSetter(double value)
            {
                var setter = new Setter(Layoutable.WidthProperty, value);
                Animation.SetAnimator(setter, animator);
                return setter;
            }

            var animation = new Animation
            {
                Duration = TimeSpan.FromSeconds(1),
                Delay = TimeSpan.FromSeconds(0),
                DelayBetweenIterations = TimeSpan.FromSeconds(0),
                IterationCount = new IterationCount(1),
                Easing = new LinearEasing(),
                Children =
                {
                    new KeyFrame
                    {
                        Setters = { CreateWidthSetter(100d) },
                        Cue = new Cue(0d)
                    },
                    new KeyFrame
                    {
                        Setters = { CreateWidthSetter(200d) },
                        Cue = new Cue(1d)
                    }
                }
            };

            var border = new Border
            {
                Height = 100d,
                Width = 50d
            };

            var clock = new TestClock();
            var animationRun = animation.RunAsync(border, clock);

            clock.Step(TimeSpan.Zero);
            Assert.Equal(1, animator.CallCount);
            Assert.Equal(0.0d, animator.LastProgress);
            animator.LastProgress = double.NaN;

            clock.Step(TimeSpan.FromSeconds(0.5d));
            Assert.Equal(2, animator.CallCount);
            Assert.Equal(0.5d, animator.LastProgress);
            animator.LastProgress = double.NaN;

            clock.Step(TimeSpan.FromSeconds(1.5d));
            Assert.Equal(3, animator.CallCount);
            Assert.Equal(1.0d, animator.LastProgress);

            await animationRun;
        }

        [Theory]
        [InlineData(0, 1, 2)]
        [InlineData(0, 2, 1)]
        [InlineData(1, 0, 2)]
        [InlineData(1, 2, 0)]
        [InlineData(2, 0, 1)]
        [InlineData(2, 1, 0)]
        public void KeyFrames_Order_Does_Not_Matter(int index0, int index1, int index2)
        {
            static KeyFrame CreateKeyFrame(double width, double cue)
                => new()
                {
                    Setters = { new Setter(Layoutable.WidthProperty, width) },
                    Cue = new Cue(cue)
                };

            var keyFrames = new[]
            {
                CreateKeyFrame(100.0, 0.0),
                CreateKeyFrame(200.0, 0.5),
                CreateKeyFrame(300.0, 1.0)
            };

            var animation = new Animation
            {
                Duration = TimeSpan.FromSeconds(1.0),
                IterationCount = new IterationCount(1),
                Easing = new LinearEasing(),
                FillMode = FillMode.Forward
            };

            animation.Children.Add(keyFrames[index0]);
            animation.Children.Add(keyFrames[index1]);
            animation.Children.Add(keyFrames[index2]);

            var border = new Border
            {
                Height = 100.0,
                Width = 50.0
            };

            var clock = new TestClock();
            animation.RunAsync(border, clock);

            clock.Step(TimeSpan.Zero);
            Assert.Equal(100.0, border.Width);

            clock.Step(TimeSpan.FromSeconds(0.5));
            Assert.Equal(200.0, border.Width);

            clock.Step(TimeSpan.FromSeconds(1.0));
            Assert.Equal(300.0, border.Width);
        }

        [Theory]
        [InlineData(0.0)]
        [InlineData(0.5)]
        [InlineData(1.0)]
        public void Single_KeyFrame_Works(double cue)
        {
            var animation = new Animation
            {
                Duration = TimeSpan.FromSeconds(1.0),
                IterationCount = new IterationCount(1),
                Easing = new LinearEasing(),
                FillMode = FillMode.Forward,
                Children =
                {
                    new KeyFrame
                    {
                        Setters = { new Setter(Layoutable.WidthProperty, 100.0) },
                        Cue = new Cue(cue)
                    }
                }
            };

            var border = new Border
            {
                Height = 100.0,
                Width = 50.0
            };

            var clock = new TestClock();
            animation.RunAsync(border, clock);

            clock.Step(TimeSpan.Zero);
            clock.Step(TimeSpan.FromSeconds(cue));
            Assert.Equal(100.0, border.Width);
        }

        private sealed class FakeAnimator : InterpolatingAnimator<double>
        {
            public double LastProgress { get; set; } = double.NaN;

            public int CallCount { get; set; }

            public override double Interpolate(double progress, double oldValue, double newValue)
            {
                ++CallCount;
                LastProgress = progress;
                return newValue;
            }
        }
    }
}