// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.

using System.Numerics;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Processing;
using SixLabors.ImageSharp.Processing.Drawing;
using SixLabors.ImageSharp.Processing.Drawing.Pens;
using SixLabors.ImageSharp.Processing.Overlays;
using SixLabors.Shapes;
using Xunit;

namespace SixLabors.ImageSharp.Tests.Drawing
{
    using SixLabors.Memory;

    public class DrawPathTests : FileTestBase
    {
        [Fact]
        public void ImageShouldBeOverlayedByPath()
        {
            string path = TestEnvironment.CreateOutputDirectory("Drawing", "Path");
            using (var image = new Image<Rgba32>(500, 500))
            {
                var linerSegemnt = new LinearLineSegment(
                    new Vector2(10, 10),
                    new Vector2(200, 150),
                    new Vector2(50, 300));
                var bazierSegment = new CubicBezierLineSegment(
                    new Vector2(50, 300),
                    new Vector2(500, 500),
                    new Vector2(60, 10),
                    new Vector2(10, 400));

                var p = new Path(linerSegemnt, bazierSegment);

                image.Mutate(x => x.BackgroundColor(Rgba32.Blue).Draw(Rgba32.HotPink, 5, p));
                image.Save($"{path}/Simple.png");

                Buffer2D<Rgba32> sourcePixels = image.GetRootFramePixelBuffer();
                Assert.Equal(Rgba32.HotPink, sourcePixels[11, 11]);

                Assert.Equal(Rgba32.HotPink, sourcePixels[199, 149]);

                Assert.Equal(Rgba32.Blue, sourcePixels[50, 50]);
            }
        }


        [Fact]
        public void ImageShouldBeOverlayedPathWithOpacity()
        {
            string path = TestEnvironment.CreateOutputDirectory("Drawing", "Path");

            var color = new Rgba32(Rgba32.HotPink.R, Rgba32.HotPink.G, Rgba32.HotPink.B, 150);


            var linerSegemnt = new LinearLineSegment(
                            new Vector2(10, 10),
                            new Vector2(200, 150),
                            new Vector2(50, 300)
                    );

            var bazierSegment = new CubicBezierLineSegment(new Vector2(50, 300),
                new Vector2(500, 500),
                new Vector2(60, 10),
                new Vector2(10, 400));

            var p = new Path(linerSegemnt, bazierSegment);

            using (var image = new Image<Rgba32>(500, 500))
            {
                image.Mutate(x => x.BackgroundColor(Rgba32.Blue).Draw(color, 10, p));
                image.Save($"{path}/Opacity.png");

                //shift background color towards forground color by the opacity amount
                var mergedColor = new Rgba32(
                    Vector4.Lerp(Rgba32.Blue.ToVector4(), Rgba32.HotPink.ToVector4(), 150f / 255f));

                Buffer2D<Rgba32> sourcePixels = image.GetRootFramePixelBuffer();
                Assert.Equal(mergedColor, sourcePixels[11, 11]);

                Assert.Equal(mergedColor, sourcePixels[199, 149]);

                Assert.Equal(Rgba32.Blue, sourcePixels[50, 50]);
            }
        }

        [Fact]
        public void PathExtendingOffEdgeOfImageShouldNotBeCropped()
        {

            string path = TestEnvironment.CreateOutputDirectory("Drawing", "Path");
            using (var image = new Image<Rgba32>(256, 256))
            {
                image.Mutate(x => x.Fill(Rgba32.Black));
                Pen<Rgba32> pen = Pens.Solid(Rgba32.White, 5f);

                for (int i = 0; i < 300; i += 20)
                {
                    image.Mutate(
                        x => x.DrawLines(
                            pen,
                            new SixLabors.Primitives.PointF[] { new Vector2(100, 2), new Vector2(-10, i) }));
                }

                image.Save($"{path}/ClippedLines.png");
                Buffer2D<Rgba32> sourcePixels = image.GetRootFramePixelBuffer();
                Assert.Equal(Rgba32.White, sourcePixels[0, 90]);
            }
        }
    }
}