using AcDream.App.Rendering.Gpu;
using AcDream.App.Rendering.Gpu.Gl;
using Silk.NET.OpenGL;

namespace AcDream.App.Tests.Rendering.Gpu.Gl;

public sealed class GlEnumMappingTests
{
    [Fact]
    public void VertexShapesMatchTheDeclaredComponentCounts()
    {
        Assert.Equal(new GlVertexAttributeShape(1, VertexAttribPointerType.Float, false), GlEnumMapping.VertexShapeOf(GpuVertexFormat.Float1));
        Assert.Equal(new GlVertexAttributeShape(2, VertexAttribPointerType.Float, false), GlEnumMapping.VertexShapeOf(GpuVertexFormat.Float2));
        Assert.Equal(new GlVertexAttributeShape(3, VertexAttribPointerType.Float, false), GlEnumMapping.VertexShapeOf(GpuVertexFormat.Float3));
        Assert.Equal(new GlVertexAttributeShape(4, VertexAttribPointerType.Float, false), GlEnumMapping.VertexShapeOf(GpuVertexFormat.Float4));
        Assert.Equal(new GlVertexAttributeShape(4, VertexAttribPointerType.UnsignedByte, true), GlEnumMapping.VertexShapeOf(GpuVertexFormat.UByte4Normalized));
    }

    [Fact]
    public void IndexTypesMapToTheirGlSizesAndEnums()
    {
        Assert.Equal(DrawElementsType.UnsignedShort, GlEnumMapping.DrawElementsTypeOf(GpuIndexType.UInt16));
        Assert.Equal(2, GlEnumMapping.IndexSizeBytesOf(GpuIndexType.UInt16));
        Assert.Equal(DrawElementsType.UnsignedInt, GlEnumMapping.DrawElementsTypeOf(GpuIndexType.UInt32));
        Assert.Equal(4, GlEnumMapping.IndexSizeBytesOf(GpuIndexType.UInt32));
    }

    [Fact]
    public void BlendFactorsMatchTheDocumentedFormulas()
    {
        (BlendingFactor source, BlendingFactor destination) straight = GlEnumMapping.BlendFactorsOf(GpuBlendMode.StraightAlpha);
        Assert.Equal((BlendingFactor.SrcAlpha, BlendingFactor.OneMinusSrcAlpha), straight);

        (BlendingFactor source, BlendingFactor destination) additive = GlEnumMapping.BlendFactorsOf(GpuBlendMode.Additive);
        Assert.Equal((BlendingFactor.SrcAlpha, BlendingFactor.One), additive);
    }

    [Fact]
    public void BlendNoneHasNoGlFactors()
    {
        Assert.Throws<NotSupportedException>(() => GlEnumMapping.BlendFactorsOf(GpuBlendMode.None));
    }

    [Fact]
    public void CullNoneHasNoGlCullFaceMode()
    {
        Assert.Throws<NotSupportedException>(() => GlEnumMapping.CullFaceModeOf(GpuCullMode.None));
    }

    [Fact]
    public void DepthCompareOpsMapOneToOne()
    {
        Assert.Equal(DepthFunction.Never, GlEnumMapping.DepthFunctionOf(GpuCompareOp.Never));
        Assert.Equal(DepthFunction.Less, GlEnumMapping.DepthFunctionOf(GpuCompareOp.Less));
        Assert.Equal(DepthFunction.Lequal, GlEnumMapping.DepthFunctionOf(GpuCompareOp.LessOrEqual));
        Assert.Equal(DepthFunction.Equal, GlEnumMapping.DepthFunctionOf(GpuCompareOp.Equal));
        Assert.Equal(DepthFunction.Greater, GlEnumMapping.DepthFunctionOf(GpuCompareOp.Greater));
        Assert.Equal(DepthFunction.Gequal, GlEnumMapping.DepthFunctionOf(GpuCompareOp.GreaterOrEqual));
        Assert.Equal(DepthFunction.Always, GlEnumMapping.DepthFunctionOf(GpuCompareOp.Always));
    }

    [Fact]
    public void FilterCombinationsProduceTheExpectedMinFilter()
    {
        Assert.Equal(TextureMinFilter.Nearest, GlEnumMapping.MinFilterOf(GpuFilter.Nearest, GpuMipFilter.None));
        Assert.Equal(TextureMinFilter.Linear, GlEnumMapping.MinFilterOf(GpuFilter.Linear, GpuMipFilter.None));
        Assert.Equal(TextureMinFilter.LinearMipmapLinear, GlEnumMapping.MinFilterOf(GpuFilter.Linear, GpuMipFilter.Linear));
        Assert.Equal(TextureMinFilter.NearestMipmapNearest, GlEnumMapping.MinFilterOf(GpuFilter.Nearest, GpuMipFilter.Nearest));
    }

    [Fact]
    public void EveryNonNoneEnumValueResolvesForFrontFaceAndWrapMode()
    {
        Assert.Equal(FrontFaceDirection.Ccw, GlEnumMapping.FrontFaceDirectionOf(GpuFrontFace.CounterClockwise));
        Assert.Equal(FrontFaceDirection.CW, GlEnumMapping.FrontFaceDirectionOf(GpuFrontFace.Clockwise));
        Assert.Equal(TextureWrapMode.Repeat, GlEnumMapping.WrapModeOf(GpuAddressMode.Repeat));
        Assert.Equal(TextureWrapMode.ClampToEdge, GlEnumMapping.WrapModeOf(GpuAddressMode.ClampToEdge));
    }
}