using OpenTK.Graphics.OpenGL;
using System;

namespace Ryujinx.Graphics.OpenGL
{
    static class HwCapabilities
    {
        private static Lazy<bool> _supportsAstcCompression = new Lazy<bool>(() => HasExtension("GL_KHR_texture_compression_astc_ldr"));

        private static Lazy<int> _maximumComputeSharedMemorySize = new Lazy<int>(() => GetLimit(All.MaxComputeSharedMemorySize));
        private static Lazy<int> _storageBufferOffsetAlignment   = new Lazy<int>(() => GetLimit(All.ShaderStorageBufferOffsetAlignment));

        private static Lazy<bool> _isNvidiaDriver = new Lazy<bool>(() => IsNvidiaDriver());

        public static bool SupportsAstcCompression          => _supportsAstcCompression.Value;
        public static bool SupportsNonConstantTextureOffset => _isNvidiaDriver.Value;

        public static int MaximumComputeSharedMemorySize => _maximumComputeSharedMemorySize.Value;
        public static int StorageBufferOffsetAlignment   => _storageBufferOffsetAlignment.Value;

        private static bool HasExtension(string name)
        {
            int numExtensions = GL.GetInteger(GetPName.NumExtensions);

            for (int extension = 0; extension < numExtensions; extension++)
            {
                if (GL.GetString(StringNameIndexed.Extensions, extension) == name)
                {
                    return true;
                }
            }

            return false;
        }

        private static int GetLimit(All name)
        {
            return GL.GetInteger((GetPName)name);
        }

        private static bool IsNvidiaDriver()
        {
            return GL.GetString(StringName.Vendor).Equals("NVIDIA Corporation");
        }
    }
}