// Copyright 2019 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include "VideoBackends/D3D12/DX12VertexFormat.h"

#include "Common/Assert.h"

#include "VideoCommon/VertexLoaderManager.h"
#include "VideoCommon/VertexShaderGen.h"

namespace DX12
{
static DXGI_FORMAT VarToDXGIFormat(VarType t, u32 components, bool integer)
{
  // NOTE: 3-component formats are not valid.
  static const DXGI_FORMAT float_type_lookup[][4] = {
      {DXGI_FORMAT_R8_UNORM, DXGI_FORMAT_R8G8_UNORM, DXGI_FORMAT_R8G8B8A8_UNORM,
       DXGI_FORMAT_R8G8B8A8_UNORM},  // VAR_UNSIGNED_BYTE
      {DXGI_FORMAT_R8_SNORM, DXGI_FORMAT_R8G8_SNORM, DXGI_FORMAT_R8G8B8A8_SNORM,
       DXGI_FORMAT_R8G8B8A8_SNORM},  // VAR_BYTE
      {DXGI_FORMAT_R16_UNORM, DXGI_FORMAT_R16G16_UNORM, DXGI_FORMAT_R16G16B16A16_UNORM,
       DXGI_FORMAT_R16G16B16A16_UNORM},  // VAR_UNSIGNED_SHORT
      {DXGI_FORMAT_R16_SNORM, DXGI_FORMAT_R16G16_SNORM, DXGI_FORMAT_R16G16B16A16_SNORM,
       DXGI_FORMAT_R16G16B16A16_SNORM},  // VAR_SHORT
      {DXGI_FORMAT_R32_FLOAT, DXGI_FORMAT_R32G32_FLOAT, DXGI_FORMAT_R32G32B32_FLOAT,
       DXGI_FORMAT_R32G32B32A32_FLOAT}  // VAR_FLOAT
  };

  static const DXGI_FORMAT integer_type_lookup[][4] = {
      {DXGI_FORMAT_R8_UINT, DXGI_FORMAT_R8G8_UINT, DXGI_FORMAT_R8G8B8A8_UINT,
       DXGI_FORMAT_R8G8B8A8_UINT},  // VAR_UNSIGNED_BYTE
      {DXGI_FORMAT_R8_SINT, DXGI_FORMAT_R8G8_SINT, DXGI_FORMAT_R8G8B8A8_SINT,
       DXGI_FORMAT_R8G8B8A8_SINT},  // VAR_BYTE
      {DXGI_FORMAT_R16_UINT, DXGI_FORMAT_R16G16_UINT, DXGI_FORMAT_R16G16B16A16_UINT,
       DXGI_FORMAT_R16G16B16A16_UINT},  // VAR_UNSIGNED_SHORT
      {DXGI_FORMAT_R16_SINT, DXGI_FORMAT_R16G16_SINT, DXGI_FORMAT_R16G16B16A16_SINT,
       DXGI_FORMAT_R16G16B16A16_SINT},  // VAR_SHORT
      {DXGI_FORMAT_R32_FLOAT, DXGI_FORMAT_R32G32_FLOAT, DXGI_FORMAT_R32G32B32_FLOAT,
       DXGI_FORMAT_R32G32B32A32_FLOAT}  // VAR_FLOAT
  };

  ASSERT(components > 0 && components <= 4);
  return integer ? integer_type_lookup[t][components - 1] : float_type_lookup[t][components - 1];
}

DXVertexFormat::DXVertexFormat(const PortableVertexDeclaration& vtx_decl)
    : NativeVertexFormat(vtx_decl)
{
  MapAttributes();
}

void DXVertexFormat::GetInputLayoutDesc(D3D12_INPUT_LAYOUT_DESC* desc) const
{
  desc->pInputElementDescs = m_attribute_descriptions.data();
  desc->NumElements = m_num_attributes;
}

void DXVertexFormat::AddAttribute(const char* semantic_name, u32 semantic_index, u32 slot,
                                  DXGI_FORMAT format, u32 offset)
{
  ASSERT(m_num_attributes < MAX_VERTEX_ATTRIBUTES);

  auto* attr_desc = &m_attribute_descriptions[m_num_attributes];
  attr_desc->SemanticName = semantic_name;
  attr_desc->SemanticIndex = semantic_index;
  attr_desc->Format = format;
  attr_desc->InputSlot = slot;
  attr_desc->AlignedByteOffset = offset;
  attr_desc->InputSlotClass = D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA;
  attr_desc->InstanceDataStepRate = 0;

  m_num_attributes++;
}

void DXVertexFormat::MapAttributes()
{
  m_num_attributes = 0;

  if (m_decl.position.enable)
  {
    AddAttribute(
        "POSITION", 0, 0,
        VarToDXGIFormat(m_decl.position.type, m_decl.position.components, m_decl.position.integer),
        m_decl.position.offset);
  }

  for (uint32_t i = 0; i < 3; i++)
  {
    if (m_decl.normals[i].enable)
    {
      AddAttribute("NORMAL", i, 0,
                   VarToDXGIFormat(m_decl.normals[i].type, m_decl.normals[i].components,
                                   m_decl.normals[i].integer),
                   m_decl.normals[i].offset);
    }
  }

  for (uint32_t i = 0; i < 2; i++)
  {
    if (m_decl.colors[i].enable)
    {
      AddAttribute("COLOR", i, 0,
                   VarToDXGIFormat(m_decl.colors[i].type, m_decl.colors[i].components,
                                   m_decl.colors[i].integer),
                   m_decl.colors[i].offset);
    }
  }

  for (uint32_t i = 0; i < 8; i++)
  {
    if (m_decl.texcoords[i].enable)
    {
      AddAttribute("TEXCOORD", i, 0,
                   VarToDXGIFormat(m_decl.texcoords[i].type, m_decl.texcoords[i].components,
                                   m_decl.texcoords[i].integer),
                   m_decl.texcoords[i].offset);
    }
  }

  if (m_decl.posmtx.enable)
  {
    AddAttribute(
        "BLENDINDICES", 0, 0,
        VarToDXGIFormat(m_decl.posmtx.type, m_decl.posmtx.components, m_decl.posmtx.integer),
        m_decl.posmtx.offset);
  }
}

}  // namespace DX12