using System.Collections.Immutable;
using System.Security.Cryptography.X509Certificates;
using Dashboard.Drawing;
using OpenTK.Graphics.OpenGL;

namespace Dashboard.OpenGL.Drawing
{
    public class GLShader : IShader
    {
        public GLDeviceContext Context { get; }
        public int Handle { get; }

        public ImmutableList<ShaderMappingProperty> Attributes { get; }

        public ImmutableList<ShaderMappingProperty> Uniforms { get; }

        public ImmutableList<ShaderMappingProperty> Blocks { get; }

        public ImmutableList<ShaderMappingProperty> Textures { get; }

        public GLShader(GLDeviceContext context, int handle)
        {
            Context = context;
            Handle = handle;

            List<ShaderMappingProperty> list = new List<ShaderMappingProperty>();
            List<ShaderMappingProperty> list2 = new List<ShaderMappingProperty>();

            int count = GL.GetProgrami(handle, ProgramProperty.ActiveAttributes);
            for (int i = 0; i < count; i++)
            {
                list.Add(GetAttribute(handle, i));
            }
            Attributes = list.ToImmutableList();

            list.Clear();
            count = GL.GetProgrami(handle, ProgramProperty.ActiveUniforms);
            for (int i = 0; i < count; i++)
            {
                var property = GetUniform(handle, i, out bool isSampler);
                list.Add(property);
                if (isSampler)
                    list2.Add(property);
            }
            Uniforms = list.ToImmutableList();
            Textures = list2.ToImmutableList();

            list.Clear();
            count = GL.GetProgrami(handle, ProgramProperty.ActiveUniformBlocks);
            for (int i = 0; i < count; i++)
            {
                var property = GetBlock(handle, i);
                list.Add(property);
            }
            Blocks = list.ToImmutableList();
        }

        private static ShaderMappingProperty GetAttribute(int program, int index)
        {
            string name = GL.GetActiveAttrib(program, (uint)index, 260, out _, out _, out _);
            int location = GL.GetAttribLocation(program, name);

            return new ShaderMappingProperty(name, location);
        }

        private static ShaderMappingProperty GetUniform(int program, int index, out bool isSampler)
        {
            string name = GL.GetActiveUniform(program, (uint)index, 260, out _,  out _, out OpenTK.Graphics.OpenGL.UniformType type);
            int location = GL.GetUniformLocation(program, name);

            isSampler = type switch
            {
                OpenTK.Graphics.OpenGL.UniformType.Sampler1D or 
                OpenTK.Graphics.OpenGL.UniformType.Sampler1DArray or
                OpenTK.Graphics.OpenGL.UniformType.Sampler1DShadow or
                OpenTK.Graphics.OpenGL.UniformType.Sampler1DArrayShadow or
                OpenTK.Graphics.OpenGL.UniformType.IntSampler1D or
                OpenTK.Graphics.OpenGL.UniformType.IntSampler1DArray or
                OpenTK.Graphics.OpenGL.UniformType.UnsignedIntSampler1D or
                OpenTK.Graphics.OpenGL.UniformType.UnsignedIntSampler1DArray or
                
                OpenTK.Graphics.OpenGL.UniformType.Sampler2D or
                OpenTK.Graphics.OpenGL.UniformType.Sampler2DShadow or
                OpenTK.Graphics.OpenGL.UniformType.Sampler2DRect or
                OpenTK.Graphics.OpenGL.UniformType.Sampler2DRectShadow or
                OpenTK.Graphics.OpenGL.UniformType.Sampler2DArray or
                OpenTK.Graphics.OpenGL.UniformType.Sampler2DArrayShadow or
                OpenTK.Graphics.OpenGL.UniformType.Sampler2DMultisample or
                OpenTK.Graphics.OpenGL.UniformType.Sampler2DMultisampleArray or
                OpenTK.Graphics.OpenGL.UniformType.IntSampler2D or
                OpenTK.Graphics.OpenGL.UniformType.IntSampler2DRect or
                OpenTK.Graphics.OpenGL.UniformType.IntSampler2DArray or
                OpenTK.Graphics.OpenGL.UniformType.IntSampler2DMultisample or
                OpenTK.Graphics.OpenGL.UniformType.IntSampler2DMultisampleArray or
                OpenTK.Graphics.OpenGL.UniformType.UnsignedIntSampler2D or
                OpenTK.Graphics.OpenGL.UniformType.UnsignedIntSampler2DRect or
                OpenTK.Graphics.OpenGL.UniformType.UnsignedIntSampler2DArray or
                OpenTK.Graphics.OpenGL.UniformType.UnsignedIntSampler2DMultisample or
                OpenTK.Graphics.OpenGL.UniformType.UnsignedIntSampler2DMultisampleArray or
                
                OpenTK.Graphics.OpenGL.UniformType.Sampler3D or
                OpenTK.Graphics.OpenGL.UniformType.IntSampler3D or
                OpenTK.Graphics.OpenGL.UniformType.UnsignedIntSampler3D or
                OpenTK.Graphics.OpenGL.UniformType.SamplerCube or
                OpenTK.Graphics.OpenGL.UniformType.SamplerCubeShadow or
                OpenTK.Graphics.OpenGL.UniformType.SamplerCubeMapArray or
                OpenTK.Graphics.OpenGL.UniformType.SamplerCubeMapArrayShadow or
                OpenTK.Graphics.OpenGL.UniformType.IntSamplerCube or
                OpenTK.Graphics.OpenGL.UniformType.IntSamplerCubeMapArray or
                OpenTK.Graphics.OpenGL.UniformType.UnsignedIntSamplerCube or
                OpenTK.Graphics.OpenGL.UniformType.UnsignedIntSamplerCubeMapArray
                    => true,
                _   => false,
            };

            return new ShaderMappingProperty(name, location);
        }

        private static ShaderMappingProperty GetBlock(int program, int index)
        {
            int size = 0;

            unsafe
            {
                GL.GetActiveUniformBlockiv(program, (uint)index, UniformBlockPName.UniformBlockDataSize, &size);
            }

            GL.GetActiveUniformBlockName(program, (uint)index, 1024, out _, out string name);
            return new ShaderMappingProperty(name, index);
        }

        public void Dispose()
        {
            Context.Collector.DeleteProgram(Handle);
        }
    }
}