// Copyright (c) 2008-2023 the Urho3D project
// License: MIT

#include "../../Precompiled.h"

#include "../../Graphics/Graphics.h"
#include "../../GraphicsAPI/Direct3D11/D3D11GraphicsImpl.h"
#include "../../GraphicsAPI/ShaderVariation.h"
#include "../../GraphicsAPI/VertexBuffer.h"
#include "../../IO/Log.h"
#include "D3D11VertexDeclaration.h"

#include "../../DebugNew.h"

namespace Urho3D
{

static const DXGI_FORMAT d3dElementFormats[] =
{
    DXGI_FORMAT_R32_SINT,
    DXGI_FORMAT_R32_FLOAT,
    DXGI_FORMAT_R32G32_FLOAT,
    DXGI_FORMAT_R32G32B32_FLOAT,
    DXGI_FORMAT_R32G32B32A32_FLOAT,
    DXGI_FORMAT_R8G8B8A8_UINT,
    DXGI_FORMAT_R8G8B8A8_UNORM
};

VertexDeclaration_D3D11::VertexDeclaration_D3D11(Graphics* graphics, ShaderVariation* vertexShader, VertexBuffer** vertexBuffers) :
    inputLayout_(nullptr)
{
    Vector<D3D11_INPUT_ELEMENT_DESC> elementDescs;
    i32 prevBufferDescs = 0;

    for (i32 i = 0; i < MAX_VERTEX_STREAMS; ++i)
    {
        if (!vertexBuffers[i])
            continue;

        const Vector<VertexElement>& srcElements = vertexBuffers[i]->GetElements();
        bool isExisting = false;

        for (const VertexElement& srcElement : srcElements)
        {
            const char* semanticName = ShaderVariation::elementSemanticNames_D3D11[srcElement.semantic_];

            // Override existing element if necessary
            for (i32 k = 0; k < prevBufferDescs; ++k)
            {
                if (elementDescs[k].SemanticName == semanticName && elementDescs[k].SemanticIndex == srcElement.index_)
                {
                    isExisting = true;
                    elementDescs[k].InputSlot = (UINT)i;
                    elementDescs[k].AlignedByteOffset = (UINT)srcElement.offset_;
                    elementDescs[k].InputSlotClass = srcElement.perInstance_ ? D3D11_INPUT_PER_INSTANCE_DATA : D3D11_INPUT_PER_VERTEX_DATA;
                    elementDescs[k].InstanceDataStepRate = srcElement.perInstance_ ? 1 : 0;
                    break;
                }
            }

            if (isExisting)
                continue;

            D3D11_INPUT_ELEMENT_DESC newDesc;
            newDesc.SemanticName = semanticName;
            newDesc.SemanticIndex = srcElement.index_;
            newDesc.Format = d3dElementFormats[srcElement.type_];
            newDesc.InputSlot = (UINT)i;
            newDesc.AlignedByteOffset = (UINT)srcElement.offset_;
            newDesc.InputSlotClass = srcElement.perInstance_ ? D3D11_INPUT_PER_INSTANCE_DATA : D3D11_INPUT_PER_VERTEX_DATA;
            newDesc.InstanceDataStepRate = srcElement.perInstance_ ? 1 : 0;
            elementDescs.Push(newDesc);
        }

        prevBufferDescs = elementDescs.Size();
    }

    if (elementDescs.Empty())
        return;

    const Vector<u8>& byteCode = vertexShader->GetByteCode();

    HRESULT hr = graphics->GetImpl_D3D11()->GetDevice()->CreateInputLayout(&elementDescs[0], (UINT)elementDescs.Size(), &byteCode[0],
        (SIZE_T)byteCode.Size(), (ID3D11InputLayout**)&inputLayout_);
    if (FAILED(hr))
    {
        URHO3D_SAFE_RELEASE(inputLayout_);
        URHO3D_LOGERRORF("Failed to create input layout for shader %s due to missing vertex element(s) (HRESULT %x)",
            vertexShader->GetFullName().CString(), (unsigned)hr);
    }
}

VertexDeclaration_D3D11::~VertexDeclaration_D3D11()
{
    URHO3D_SAFE_RELEASE(inputLayout_);
}

}