// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

using System.Numerics;
using System.Runtime.CompilerServices;
using SixLabors.ImageSharp.PixelFormats;

namespace SixLabors.ImageSharp.Tests.PixelFormats;

[Trait("Category", "PixelFormats")]
public class HalfVector4Tests
{
    [Fact]
    public void HalfVector4_PackedValue()
    {
        Assert.Equal(0uL, new HalfVector4(Vector4.Zero).PackedValue);
        Assert.Equal(4323521613979991040uL, new HalfVector4(Vector4.One).PackedValue);
        Assert.Equal(13547034390470638592uL, new HalfVector4(-Vector4.One).PackedValue);
        Assert.Equal(15360uL, new HalfVector4(Vector4.UnitX).PackedValue);
        Assert.Equal(1006632960uL, new HalfVector4(Vector4.UnitY).PackedValue);
        Assert.Equal(65970697666560uL, new HalfVector4(Vector4.UnitZ).PackedValue);
        Assert.Equal(4323455642275676160uL, new HalfVector4(Vector4.UnitW).PackedValue);
        Assert.Equal(4035285078724390502uL, new HalfVector4(0.1f, 0.3f, 0.4f, 0.5f).PackedValue);
    }

    [Fact]
    public void HalfVector4_ToVector4()
    {
        Assert.Equal(Vector4.Zero, new HalfVector4(Vector4.Zero).ToVector4());
        Assert.Equal(Vector4.One, new HalfVector4(Vector4.One).ToVector4());
        Assert.Equal(-Vector4.One, new HalfVector4(-Vector4.One).ToVector4());
        Assert.Equal(Vector4.UnitX, new HalfVector4(Vector4.UnitX).ToVector4());
        Assert.Equal(Vector4.UnitY, new HalfVector4(Vector4.UnitY).ToVector4());
        Assert.Equal(Vector4.UnitZ, new HalfVector4(Vector4.UnitZ).ToVector4());
        Assert.Equal(Vector4.UnitW, new HalfVector4(Vector4.UnitW).ToVector4());
        Assert.Equal(new Vector4(-2F, 4F, .5F, 8F), new HalfVector4(-2F, 4F, .5F, 8F).ToVector4());
        Assert.Equal(
            new Vector4((float)Half.MinValue, (float)Half.MaxValue, (float)Half.MinValue, (float)Half.MaxValue),
            new HalfVector4((float)Half.MinValue, (float)Half.MaxValue, (float)Half.MinValue, (float)Half.MaxValue).ToVector4());
    }

    [Fact]
    public void HalfVector4_ToScaledVector4()
    {
        // arrange
        Vector4 expected = new(0F, .5F, 1F, 0F);
        HalfVector4 pixel = new((float)Half.MinValue, 0F, (float)Half.MaxValue, (float)Half.MinValue);

        // act
        Vector4 actual = pixel.ToScaledVector4();

        // assert
        Assert.Equal(expected, actual);
    }

    [Fact]
    public void HalfVector4_FromScaledVector4()
    {
        // arrange
        Vector4 scaled = new(0F, .25F, .5F, 1F);
        ulong expected = new HalfVector4((float)Half.MinValue, -32752F, 0F, (float)Half.MaxValue).PackedValue;

        // act
        HalfVector4 pixel = HalfVector4.FromScaledVector4(scaled);
        ulong actual = pixel.PackedValue;

        // assert
        Assert.Equal(expected, actual);
    }

    [Fact]
    public void HalfVector4_BulkScaledConversionsCoverFiniteRange()
    {
        const ulong packedValue = 0xFBFF_7BFF_0000_FBFF;
        HalfVector4 pixel = new() { PackedValue = packedValue };
        HalfVector4[] source = new HalfVector4[17];
        Vector4[] expectedVectors = new Vector4[source.Length];
        Array.Fill(source, pixel);
        Array.Fill(expectedVectors, new Vector4(0F, .5F, 1F, 0F));

        Vector4[] actualVectors = new Vector4[source.Length];
        PixelOperations<HalfVector4>.Instance.ToVector4(Configuration.Default, source, actualVectors, PixelConversionModifiers.Scale);
        Assert.Equal(expectedVectors, actualVectors);

        Vector4[] destructiveSource = [.. expectedVectors];
        HalfVector4[] actualPixels = new HalfVector4[source.Length];
        PixelOperations<HalfVector4>.Instance.FromVector4Destructive(Configuration.Default, destructiveSource, actualPixels, PixelConversionModifiers.Scale);
        Assert.Equal(source, actualPixels);
    }

    [Fact]
    public void HalfVector4_FromBgra5551()
    {
        // arrange
        Vector4 expected = Vector4.One;

        // act
        HalfVector4 pixel = HalfVector4.FromBgra5551(new Bgra5551(1.0f, 1.0f, 1.0f, 1.0f));

        // assert
        Assert.Equal(expected, pixel.ToScaledVector4());
    }

    [Fact]
    public void HalfVector4_PixelInformation()
    {
        PixelTypeInfo info = HalfVector4.GetPixelTypeInfo();
        Assert.Equal(Unsafe.SizeOf<HalfVector4>() * 8, info.BitsPerPixel);
        Assert.Equal(PixelAlphaRepresentation.Unassociated, info.AlphaRepresentation);
        Assert.Equal(PixelColorType.RGB | PixelColorType.Alpha, info.ColorType);

        PixelComponentInfo componentInfo = info.ComponentInfo.Value;
        Assert.Equal(4, componentInfo.ComponentCount);
        Assert.Equal(0, componentInfo.Padding);
        Assert.Equal(16, componentInfo.GetComponentPrecision(0));
        Assert.Equal(16, componentInfo.GetComponentPrecision(1));
        Assert.Equal(16, componentInfo.GetComponentPrecision(2));
        Assert.Equal(16, componentInfo.GetComponentPrecision(3));
        Assert.Equal(16, componentInfo.GetMaximumComponentPrecision());
    }
}