using Ryujinx.Graphics.Shader;
using System;
using System.Runtime.CompilerServices;

namespace Ryujinx.Graphics.Gpu.Memory
{
    /// <summary>
    /// Pipeline stages that can modify buffer data, as well as flags indicating storage usage.
    /// Must match ShaderStage for the shader stages, though anything after that can be in any order.
    /// </summary>
    [Flags]
    internal enum BufferStage : byte
    {
        Compute,
        Vertex,
        TessellationControl,
        TessellationEvaluation,
        Geometry,
        Fragment,

        Indirect,
        VertexBuffer,
        IndexBuffer,
        Copy,
        TransformFeedback,
        Internal,
        None,

        StageMask = 0x3f,
        StorageMask = 0xc0,

        StorageRead = 0x40,
        StorageWrite = 0x80,
        StorageAtomic = 0xc0
    }

    /// <summary>
    /// Utility methods to convert shader stages and binding flags into buffer stages.
    /// </summary>
    internal static class BufferStageUtils
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static BufferStage FromShaderStage(ShaderStage stage)
        {
            return (BufferStage)stage;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static BufferStage FromShaderStage(int stageIndex)
        {
            return (BufferStage)(stageIndex + 1);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static BufferStage FromUsage(BufferUsageFlags flags)
        {
            if ((flags & BufferUsageFlags.Write) == BufferUsageFlags.Write)
            {
                return BufferStage.StorageWrite;
            }
            else
            {
                return BufferStage.StorageRead;
            }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static BufferStage FromUsage(TextureUsageFlags flags)
        {
            if ((flags & TextureUsageFlags.ImageStore) == TextureUsageFlags.ImageStore)
            {
                return BufferStage.StorageWrite;
            }
            else
            {
                return BufferStage.StorageRead;
            }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static BufferStage TextureBuffer(ShaderStage shaderStage, TextureUsageFlags flags)
        {
            return FromShaderStage(shaderStage) | FromUsage(flags);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static BufferStage GraphicsStorage(int stageIndex, BufferUsageFlags flags)
        {
            return FromShaderStage(stageIndex) | FromUsage(flags);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static BufferStage ComputeStorage(BufferUsageFlags flags)
        {
            return BufferStage.Compute | FromUsage(flags);
        }
    }
}
