// Copyright 2014 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include <string>

#include "Common/FileUtil.h"
#include "Common/LinearDiskCache.h"
#include "Common/StringUtil.h"

#include "Core/ConfigManager.h"

#include "VideoBackends/D3D/D3DBase.h"
#include "VideoBackends/D3D/D3DShader.h"
#include "VideoBackends/D3D/FramebufferManager.h"
#include "VideoBackends/D3D/GeometryShaderCache.h"

#include "VideoCommon/Debugger.h"
#include "VideoCommon/GeometryShaderGen.h"
#include "VideoCommon/GeometryShaderManager.h"
#include "VideoCommon/Statistics.h"
#include "VideoCommon/VideoConfig.h"

namespace DX11
{
GeometryShaderCache::GSCache GeometryShaderCache::GeometryShaders;
const GeometryShaderCache::GSCacheEntry* GeometryShaderCache::last_entry;
GeometryShaderUid GeometryShaderCache::last_uid;
const GeometryShaderCache::GSCacheEntry GeometryShaderCache::pass_entry;

ID3D11GeometryShader* ClearGeometryShader = nullptr;
ID3D11GeometryShader* CopyGeometryShader = nullptr;

LinearDiskCache<GeometryShaderUid, u8> g_gs_disk_cache;

ID3D11GeometryShader* GeometryShaderCache::GetClearGeometryShader()
{
  return (g_ActiveConfig.iStereoMode > 0) ? ClearGeometryShader : nullptr;
}
ID3D11GeometryShader* GeometryShaderCache::GetCopyGeometryShader()
{
  return (g_ActiveConfig.iStereoMode > 0) ? CopyGeometryShader : nullptr;
}

ID3D11Buffer* gscbuf = nullptr;

ID3D11Buffer*& GeometryShaderCache::GetConstantBuffer()
{
  // TODO: divide the global variables of the generated shaders into about 5 constant buffers to
  // speed this up
  if (GeometryShaderManager::dirty)
  {
    D3D11_MAPPED_SUBRESOURCE map;
    D3D::context->Map(gscbuf, 0, D3D11_MAP_WRITE_DISCARD, 0, &map);
    memcpy(map.pData, &GeometryShaderManager::constants, sizeof(GeometryShaderConstants));
    D3D::context->Unmap(gscbuf, 0);
    GeometryShaderManager::dirty = false;

    ADDSTAT(stats.thisFrame.bytesUniformStreamed, sizeof(GeometryShaderConstants));
  }
  return gscbuf;
}

// this class will load the precompiled shaders into our cache
class GeometryShaderCacheInserter : public LinearDiskCacheReader<GeometryShaderUid, u8>
{
public:
  void Read(const GeometryShaderUid& key, const u8* value, u32 value_size)
  {
    GeometryShaderCache::InsertByteCode(key, value, value_size);
  }
};

const char clear_shader_code[] = {
    "struct VSOUTPUT\n"
    "{\n"
    "	float4 vPosition   : POSITION;\n"
    "	float4 vColor0   : COLOR0;\n"
    "};\n"
    "struct GSOUTPUT\n"
    "{\n"
    "	float4 vPosition   : POSITION;\n"
    "	float4 vColor0   : COLOR0;\n"
    "	uint slice    : SV_RenderTargetArrayIndex;\n"
    "};\n"
    "[maxvertexcount(6)]\n"
    "void main(triangle VSOUTPUT o[3], inout TriangleStream<GSOUTPUT> Output)\n"
    "{\n"
    "for(int slice = 0; slice < 2; slice++)\n"
    "{\n"
    "	for(int i = 0; i < 3; i++)\n"
    "	{\n"
    "		GSOUTPUT OUT;\n"
    "		OUT.vPosition = o[i].vPosition;\n"
    "		OUT.vColor0 = o[i].vColor0;\n"
    "		OUT.slice = slice;\n"
    "		Output.Append(OUT);\n"
    "	}\n"
    "	Output.RestartStrip();\n"
    "}\n"
    "}\n"};

const char copy_shader_code[] = {
    "struct VSOUTPUT\n"
    "{\n"
    "	float4 vPosition : POSITION;\n"
    "	float3 vTexCoord : TEXCOORD0;\n"
    "	float  vTexCoord1 : TEXCOORD1;\n"
    "};\n"
    "struct GSOUTPUT\n"
    "{\n"
    "	float4 vPosition : POSITION;\n"
    "	float3 vTexCoord : TEXCOORD0;\n"
    "	float  vTexCoord1 : TEXCOORD1;\n"
    "	uint slice    : SV_RenderTargetArrayIndex;\n"
    "};\n"
    "[maxvertexcount(6)]\n"
    "void main(triangle VSOUTPUT o[3], inout TriangleStream<GSOUTPUT> Output)\n"
    "{\n"
    "for(int slice = 0; slice < 2; slice++)\n"
    "{\n"
    "	for(int i = 0; i < 3; i++)\n"
    "	{\n"
    "		GSOUTPUT OUT;\n"
    "		OUT.vPosition = o[i].vPosition;\n"
    "		OUT.vTexCoord = o[i].vTexCoord;\n"
    "		OUT.vTexCoord.z = slice;\n"
    "		OUT.vTexCoord1 = o[i].vTexCoord1;\n"
    "		OUT.slice = slice;\n"
    "		Output.Append(OUT);\n"
    "	}\n"
    "	Output.RestartStrip();\n"
    "}\n"
    "}\n"};

void GeometryShaderCache::Init()
{
  unsigned int gbsize = ROUND_UP(sizeof(GeometryShaderConstants), 16);  // must be a multiple of 16
  D3D11_BUFFER_DESC gbdesc = CD3D11_BUFFER_DESC(gbsize, D3D11_BIND_CONSTANT_BUFFER,
                                                D3D11_USAGE_DYNAMIC, D3D11_CPU_ACCESS_WRITE);
  HRESULT hr = D3D::device->CreateBuffer(&gbdesc, nullptr, &gscbuf);
  CHECK(hr == S_OK, "Create geometry shader constant buffer (size=%u)", gbsize);
  D3D::SetDebugObjectName((ID3D11DeviceChild*)gscbuf,
                          "geometry shader constant buffer used to emulate the GX pipeline");

  // used when drawing clear quads
  ClearGeometryShader = D3D::CompileAndCreateGeometryShader(clear_shader_code);
  CHECK(ClearGeometryShader != nullptr, "Create clear geometry shader");
  D3D::SetDebugObjectName((ID3D11DeviceChild*)ClearGeometryShader, "clear geometry shader");

  // used for buffer copy
  CopyGeometryShader = D3D::CompileAndCreateGeometryShader(copy_shader_code);
  CHECK(CopyGeometryShader != nullptr, "Create copy geometry shader");
  D3D::SetDebugObjectName((ID3D11DeviceChild*)CopyGeometryShader, "copy geometry shader");

  Clear();

  if (!File::Exists(File::GetUserPath(D_SHADERCACHE_IDX)))
    File::CreateDir(File::GetUserPath(D_SHADERCACHE_IDX));

  std::string cache_filename =
      StringFromFormat("%sdx11-%s-gs.cache", File::GetUserPath(D_SHADERCACHE_IDX).c_str(),
                       SConfig::GetInstance().m_strUniqueID.c_str());
  GeometryShaderCacheInserter inserter;
  g_gs_disk_cache.OpenAndRead(cache_filename, inserter);

  last_entry = nullptr;
}

// ONLY to be used during shutdown.
void GeometryShaderCache::Clear()
{
  for (auto& iter : GeometryShaders)
    iter.second.Destroy();
  GeometryShaders.clear();

  last_entry = nullptr;
}

void GeometryShaderCache::Shutdown()
{
  SAFE_RELEASE(gscbuf);

  SAFE_RELEASE(ClearGeometryShader);
  SAFE_RELEASE(CopyGeometryShader);

  Clear();
  g_gs_disk_cache.Sync();
  g_gs_disk_cache.Close();
}

bool GeometryShaderCache::SetShader(u32 primitive_type)
{
  GeometryShaderUid uid = GetGeometryShaderUid(primitive_type);

  // Check if the shader is already set
  if (last_entry)
  {
    if (uid == last_uid)
    {
      GFX_DEBUGGER_PAUSE_AT(NEXT_PIXEL_SHADER_CHANGE, true);
      return true;
    }
  }

  last_uid = uid;

  // Check if the shader is a pass-through shader
  if (uid.GetUidData()->IsPassthrough())
  {
    // Return the default pass-through shader
    last_entry = &pass_entry;
    return true;
  }

  // Check if the shader is already in the cache
  GSCache::iterator iter;
  iter = GeometryShaders.find(uid);
  if (iter != GeometryShaders.end())
  {
    const GSCacheEntry& entry = iter->second;
    last_entry = &entry;

    return (entry.shader != nullptr);
  }

  // Need to compile a new shader
  ShaderCode code = GenerateGeometryShaderCode(API_D3D, uid.GetUidData());

  D3DBlob* pbytecode;
  if (!D3D::CompileGeometryShader(code.GetBuffer(), &pbytecode))
  {
    GFX_DEBUGGER_PAUSE_AT(NEXT_ERROR, true);
    return false;
  }

  // Insert the bytecode into the caches
  g_gs_disk_cache.Append(uid, pbytecode->Data(), pbytecode->Size());

  bool success = InsertByteCode(uid, pbytecode->Data(), pbytecode->Size());
  pbytecode->Release();

  return success;
}

bool GeometryShaderCache::InsertByteCode(const GeometryShaderUid& uid, const void* bytecode,
                                         unsigned int bytecodelen)
{
  ID3D11GeometryShader* shader = D3D::CreateGeometryShaderFromByteCode(bytecode, bytecodelen);
  if (shader == nullptr)
    return false;

  // TODO: Somehow make the debug name a bit more specific
  D3D::SetDebugObjectName((ID3D11DeviceChild*)shader, "a pixel shader of GeometryShaderCache");

  // Make an entry in the table
  GSCacheEntry newentry;
  newentry.shader = shader;
  GeometryShaders[uid] = newentry;
  last_entry = &GeometryShaders[uid];

  if (!shader)
    return false;

  return true;
}

}  // DX11
