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

using System.Globalization;
using System.Numerics;
using SixLabors.ImageSharp.Processing;

namespace SixLabors.ImageSharp.Tests.Primitives;

public class ColorMatrixTests
{
    private readonly ApproximateFloatComparer approximateFloatComparer = new(1e-6f);

    [Fact]
    public void ColorMatrixIdentityIsCorrect()
    {
        ColorMatrix val = default;
        val.M11 = val.M22 = val.M33 = val.M44 = 1F;

        Assert.Equal(val, ColorMatrix.Identity, this.approximateFloatComparer);
    }

    [Fact]
    public void ColorMatrixCanDetectIdentity()
    {
        ColorMatrix m = ColorMatrix.Identity;
        Assert.True(m.IsIdentity);

        m.M12 = 1F;
        Assert.False(m.IsIdentity);
    }

    [Fact]
    public void ColorMatrixEquality()
    {
        ColorMatrix m = KnownFilterMatrices.CreateHueFilter(45F);
        ColorMatrix m2 = KnownFilterMatrices.CreateHueFilter(45F);
        object obj = m2;

        Assert.True(m.Equals(obj));
        Assert.True(m.Equals(m2));
        Assert.True(m == m2);
        Assert.False(m != m2);
    }

    [Fact]
    public void ColorMatrixMultiply()
    {
        ColorMatrix value1 = CreateAllTwos();
        ColorMatrix value2 = CreateAllThrees();

        ColorMatrix m = default(ColorMatrix);

        // First row
        m.M11 = (value1.M11 * value2.M11) + (value1.M12 * value2.M21) + (value1.M13 * value2.M31) + (value1.M14 * value2.M41);
        m.M12 = (value1.M11 * value2.M12) + (value1.M12 * value2.M22) + (value1.M13 * value2.M32) + (value1.M14 * value2.M42);
        m.M13 = (value1.M11 * value2.M13) + (value1.M12 * value2.M23) + (value1.M13 * value2.M33) + (value1.M14 * value2.M43);
        m.M14 = (value1.M11 * value2.M14) + (value1.M12 * value2.M24) + (value1.M13 * value2.M34) + (value1.M14 * value2.M44);

        // Second row
        m.M21 = (value1.M21 * value2.M11) + (value1.M22 * value2.M21) + (value1.M23 * value2.M31) + (value1.M24 * value2.M41);
        m.M22 = (value1.M21 * value2.M12) + (value1.M22 * value2.M22) + (value1.M23 * value2.M32) + (value1.M24 * value2.M42);
        m.M23 = (value1.M21 * value2.M13) + (value1.M22 * value2.M23) + (value1.M23 * value2.M33) + (value1.M24 * value2.M43);
        m.M24 = (value1.M21 * value2.M14) + (value1.M22 * value2.M24) + (value1.M23 * value2.M34) + (value1.M24 * value2.M44);

        // Third row
        m.M31 = (value1.M31 * value2.M11) + (value1.M32 * value2.M21) + (value1.M33 * value2.M31) + (value1.M34 * value2.M41);
        m.M32 = (value1.M31 * value2.M12) + (value1.M32 * value2.M22) + (value1.M33 * value2.M32) + (value1.M34 * value2.M42);
        m.M33 = (value1.M31 * value2.M13) + (value1.M32 * value2.M23) + (value1.M33 * value2.M33) + (value1.M34 * value2.M43);
        m.M34 = (value1.M31 * value2.M14) + (value1.M32 * value2.M24) + (value1.M33 * value2.M34) + (value1.M34 * value2.M44);

        // Fourth row
        m.M41 = (value1.M41 * value2.M11) + (value1.M42 * value2.M21) + (value1.M43 * value2.M31) + (value1.M44 * value2.M41);
        m.M42 = (value1.M41 * value2.M12) + (value1.M42 * value2.M22) + (value1.M43 * value2.M32) + (value1.M44 * value2.M42);
        m.M43 = (value1.M41 * value2.M13) + (value1.M42 * value2.M23) + (value1.M43 * value2.M33) + (value1.M44 * value2.M43);
        m.M44 = (value1.M41 * value2.M14) + (value1.M42 * value2.M24) + (value1.M43 * value2.M34) + (value1.M44 * value2.M44);

        // Fifth row
        m.M51 = (value1.M51 * value2.M11) + (value1.M52 * value2.M21) + (value1.M53 * value2.M31) + (value1.M54 * value2.M41) + value2.M51;
        m.M52 = (value1.M51 * value2.M12) + (value1.M52 * value2.M22) + (value1.M53 * value2.M32) + (value1.M54 * value2.M52) + value2.M52;
        m.M53 = (value1.M51 * value2.M13) + (value1.M52 * value2.M23) + (value1.M53 * value2.M33) + (value1.M54 * value2.M53) + value2.M53;
        m.M54 = (value1.M51 * value2.M14) + (value1.M52 * value2.M24) + (value1.M53 * value2.M34) + (value1.M54 * value2.M54) + value2.M54;

        Assert.Equal(m, value1 * value2, this.approximateFloatComparer);
    }

    [Fact]
    public void ColorMatrixMultiplyScalar()
    {
        ColorMatrix m = CreateAllTwos();
        Assert.Equal(CreateAllFours(), m * 2, this.approximateFloatComparer);
    }

    [Fact]
    public void ColorMatrixSubtract()
    {
        ColorMatrix m = CreateAllOnes() + CreateAllTwos();
        Assert.Equal(CreateAllThrees(), m);
    }

    [Fact]
    public void ColorMatrixNegate()
    {
        ColorMatrix m = CreateAllOnes() * -1F;
        Assert.Equal(m, -CreateAllOnes());
    }

    [Fact]
    public void ColorMatrixAdd()
    {
        ColorMatrix m = CreateAllOnes() + CreateAllTwos();
        Assert.Equal(CreateAllThrees(), m);
    }

    [Fact]
    public void ColorMatrixHashCode()
    {
        ColorMatrix m = KnownFilterMatrices.CreateBrightnessFilter(.5F);

        HashCode hash = default;

        Vector4 x = new(m.M11, m.M12, m.M13, m.M14);
        Vector4 y = new(m.M21, m.M22, m.M23, m.M24);
        Vector4 z = new(m.M31, m.M32, m.M33, m.M34);
        Vector4 w = new(m.M41, m.M42, m.M43, m.M44);
        Vector4 v = new(m.M51, m.M52, m.M53, m.M54);

        hash.Add(x);
        hash.Add(y);
        hash.Add(z);
        hash.Add(w);
        hash.Add(v);


        Assert.Equal(hash.ToHashCode(), m.GetHashCode());
    }

    [Fact]
    public void ColorMatrixToString()
    {
        ColorMatrix m = KnownFilterMatrices.CreateBrightnessFilter(.5F);

        CultureInfo ci = CultureInfo.CurrentCulture;

#pragma warning disable SA1117 // Parameters should be on same line or separate lines
        string expected = string.Format(ci, "{{ {{M11:{0} M12:{1} M13:{2} M14:{3}}} {{M21:{4} M22:{5} M23:{6} M24:{7}}} {{M31:{8} M32:{9} M33:{10} M34:{11}}} {{M41:{12} M42:{13} M43:{14} M44:{15}}} {{M51:{16} M52:{17} M53:{18} M54:{19}}} }}",
            m.M11.ToString(ci), m.M12.ToString(ci), m.M13.ToString(ci), m.M14.ToString(ci),
            m.M21.ToString(ci), m.M22.ToString(ci), m.M23.ToString(ci), m.M24.ToString(ci),
            m.M31.ToString(ci), m.M32.ToString(ci), m.M33.ToString(ci), m.M34.ToString(ci),
            m.M41.ToString(ci), m.M42.ToString(ci), m.M43.ToString(ci), m.M44.ToString(ci),
            m.M51.ToString(ci), m.M52.ToString(ci), m.M53.ToString(ci), m.M54.ToString(ci));
#pragma warning restore SA1117 // Parameters should be on same line or separate lines

        Assert.Equal(expected, m.ToString());
    }

    private static ColorMatrix CreateAllOnes()
        => new()
        {
            M11 = 1F,
            M12 = 1F,
            M13 = 1F,
            M14 = 1F,
            M21 = 1F,
            M22 = 1F,
            M23 = 1F,
            M24 = 1F,
            M31 = 1F,
            M32 = 1F,
            M33 = 1F,
            M34 = 1F,
            M41 = 1F,
            M42 = 1F,
            M43 = 1F,
            M44 = 1F,
            M51 = 1F,
            M52 = 1F,
            M53 = 1F,
            M54 = 1F
        };

    private static ColorMatrix CreateAllTwos()
        => new()
        {
            M11 = 2F,
            M12 = 2F,
            M13 = 2F,
            M14 = 2F,
            M21 = 2F,
            M22 = 2F,
            M23 = 2F,
            M24 = 2F,
            M31 = 2F,
            M32 = 2F,
            M33 = 2F,
            M34 = 2F,
            M41 = 2F,
            M42 = 2F,
            M43 = 2F,
            M44 = 2F,
            M51 = 2F,
            M52 = 2F,
            M53 = 2F,
            M54 = 2F
        };

    private static ColorMatrix CreateAllThrees()
        => new()
        {
            M11 = 3F,
            M12 = 3F,
            M13 = 3F,
            M14 = 3F,
            M21 = 3F,
            M22 = 3F,
            M23 = 3F,
            M24 = 3F,
            M31 = 3F,
            M32 = 3F,
            M33 = 3F,
            M34 = 3F,
            M41 = 3F,
            M42 = 3F,
            M43 = 3F,
            M44 = 3F,
            M51 = 3F,
            M52 = 3F,
            M53 = 3F,
            M54 = 3F
        };

    private static ColorMatrix CreateAllFours()
        => new()
        {
            M11 = 4F,
            M12 = 4F,
            M13 = 4F,
            M14 = 4F,
            M21 = 4F,
            M22 = 4F,
            M23 = 4F,
            M24 = 4F,
            M31 = 4F,
            M32 = 4F,
            M33 = 4F,
            M34 = 4F,
            M41 = 4F,
            M42 = 4F,
            M43 = 4F,
            M44 = 4F,
            M51 = 4F,
            M52 = 4F,
            M53 = 4F,
            M54 = 4F
        };
}