// Copyright 2012 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include <memory>

#include "Common/CommonFuncs.h"
#include "Common/CommonTypes.h"
#include "Common/GL/GLContext.h"
#include "Common/GL/GLUtil.h"

#include "VideoBackends/OGL/PerfQuery.h"
#include "VideoCommon/RenderBase.h"
#include "VideoCommon/VideoConfig.h"

namespace OGL
{
std::unique_ptr<PerfQueryBase> GetPerfQuery()
{
  if (g_main_gl_context->IsGLES() && GLExtensions::Supports("GL_NV_occlusion_query_samples"))
    return std::make_unique<PerfQueryGLESNV>();

  if (g_main_gl_context->IsGLES())
    return std::make_unique<PerfQueryGL>(GL_ANY_SAMPLES_PASSED);

  return std::make_unique<PerfQueryGL>(GL_SAMPLES_PASSED);
}

PerfQuery::PerfQuery() : m_query_read_pos()
{
  ResetQuery();
}

void PerfQuery::EnableQuery(PerfQueryGroup type)
{
  m_query->EnableQuery(type);
}

void PerfQuery::DisableQuery(PerfQueryGroup type)
{
  m_query->DisableQuery(type);
}

bool PerfQuery::IsFlushed() const
{
  return 0 == m_query_count;
}

// TODO: could selectively flush things, but I don't think that will do much
void PerfQuery::FlushResults()
{
  m_query->FlushResults();
}

void PerfQuery::ResetQuery()
{
  m_query_count = 0;
  std::fill_n(m_results, ArraySize(m_results), 0);
}

u32 PerfQuery::GetQueryResult(PerfQueryType type)
{
  u32 result = 0;

  if (type == PQ_ZCOMP_INPUT_ZCOMPLOC || type == PQ_ZCOMP_OUTPUT_ZCOMPLOC)
  {
    result = m_results[PQG_ZCOMP_ZCOMPLOC];
  }
  else if (type == PQ_ZCOMP_INPUT || type == PQ_ZCOMP_OUTPUT)
  {
    result = m_results[PQG_ZCOMP];
  }
  else if (type == PQ_BLEND_INPUT)
  {
    result = m_results[PQG_ZCOMP] + m_results[PQG_ZCOMP_ZCOMPLOC];
  }
  else if (type == PQ_EFB_COPY_CLOCKS)
  {
    result = m_results[PQG_EFB_COPY_CLOCKS];
  }

  return result;
}

// Implementations
PerfQueryGL::PerfQueryGL(GLenum query_type) : m_query_type(query_type)
{
  for (ActiveQuery& query : m_query_buffer)
    glGenQueries(1, &query.query_id);
}

PerfQueryGL::~PerfQueryGL()
{
  for (ActiveQuery& query : m_query_buffer)
    glDeleteQueries(1, &query.query_id);
}

void PerfQueryGL::EnableQuery(PerfQueryGroup type)
{
  // Is this sane?
  if (m_query_count > m_query_buffer.size() / 2)
    WeakFlush();

  if (m_query_buffer.size() == m_query_count)
  {
    FlushOne();
    // ERROR_LOG(VIDEO, "Flushed query buffer early!");
  }

  // start query
  if (type == PQG_ZCOMP_ZCOMPLOC || type == PQG_ZCOMP)
  {
    auto& entry = m_query_buffer[(m_query_read_pos + m_query_count) % m_query_buffer.size()];

    glBeginQuery(m_query_type, entry.query_id);
    entry.query_type = type;

    ++m_query_count;
  }
}
void PerfQueryGL::DisableQuery(PerfQueryGroup type)
{
  // stop query
  if (type == PQG_ZCOMP_ZCOMPLOC || type == PQG_ZCOMP)
  {
    glEndQuery(m_query_type);
  }
}

void PerfQueryGL::WeakFlush()
{
  while (!IsFlushed())
  {
    auto& entry = m_query_buffer[m_query_read_pos];

    GLuint result = GL_FALSE;
    glGetQueryObjectuiv(entry.query_id, GL_QUERY_RESULT_AVAILABLE, &result);

    if (GL_TRUE == result)
    {
      FlushOne();
    }
    else
    {
      break;
    }
  }
}

void PerfQueryGL::FlushOne()
{
  auto& entry = m_query_buffer[m_query_read_pos];

  GLuint result = 0;
  glGetQueryObjectuiv(entry.query_id, GL_QUERY_RESULT, &result);

  // NOTE: Reported pixel metrics should be referenced to native resolution
  // TODO: Dropping the lower 2 bits from this count should be closer to actual
  // hardware behavior when drawing triangles.
  result = static_cast<u64>(result) * EFB_WIDTH * EFB_HEIGHT /
           (g_renderer->GetTargetWidth() * g_renderer->GetTargetHeight());

  // Adjust for multisampling
  if (g_ActiveConfig.iMultisamples > 1)
    result /= g_ActiveConfig.iMultisamples;

  m_results[entry.query_type] += result;

  m_query_read_pos = (m_query_read_pos + 1) % m_query_buffer.size();
  --m_query_count;
}

// TODO: could selectively flush things, but I don't think that will do much
void PerfQueryGL::FlushResults()
{
  while (!IsFlushed())
    FlushOne();
}

PerfQueryGLESNV::PerfQueryGLESNV()
{
  for (ActiveQuery& query : m_query_buffer)
    glGenOcclusionQueriesNV(1, &query.query_id);
}

PerfQueryGLESNV::~PerfQueryGLESNV()
{
  for (ActiveQuery& query : m_query_buffer)
    glDeleteOcclusionQueriesNV(1, &query.query_id);
}

void PerfQueryGLESNV::EnableQuery(PerfQueryGroup type)
{
  // Is this sane?
  if (m_query_count > m_query_buffer.size() / 2)
    WeakFlush();

  if (m_query_buffer.size() == m_query_count)
  {
    FlushOne();
    // ERROR_LOG(VIDEO, "Flushed query buffer early!");
  }

  // start query
  if (type == PQG_ZCOMP_ZCOMPLOC || type == PQG_ZCOMP)
  {
    auto& entry = m_query_buffer[(m_query_read_pos + m_query_count) % m_query_buffer.size()];

    glBeginOcclusionQueryNV(entry.query_id);
    entry.query_type = type;

    ++m_query_count;
  }
}
void PerfQueryGLESNV::DisableQuery(PerfQueryGroup type)
{
  // stop query
  if (type == PQG_ZCOMP_ZCOMPLOC || type == PQG_ZCOMP)
  {
    glEndOcclusionQueryNV();
  }
}

void PerfQueryGLESNV::WeakFlush()
{
  while (!IsFlushed())
  {
    auto& entry = m_query_buffer[m_query_read_pos];

    GLuint result = GL_FALSE;
    glGetOcclusionQueryuivNV(entry.query_id, GL_PIXEL_COUNT_AVAILABLE_NV, &result);

    if (GL_TRUE == result)
    {
      FlushOne();
    }
    else
    {
      break;
    }
  }
}

void PerfQueryGLESNV::FlushOne()
{
  auto& entry = m_query_buffer[m_query_read_pos];

  GLuint result = 0;
  glGetOcclusionQueryuivNV(entry.query_id, GL_OCCLUSION_TEST_RESULT_HP, &result);

  // NOTE: Reported pixel metrics should be referenced to native resolution
  // TODO: Dropping the lower 2 bits from this count should be closer to actual
  // hardware behavior when drawing triangles.
  m_results[entry.query_type] += static_cast<u64>(result) * EFB_WIDTH * EFB_HEIGHT /
                                 (g_renderer->GetTargetWidth() * g_renderer->GetTargetHeight());

  m_query_read_pos = (m_query_read_pos + 1) % m_query_buffer.size();
  --m_query_count;
}

// TODO: could selectively flush things, but I don't think that will do much
void PerfQueryGLESNV::FlushResults()
{
  while (!IsFlushed())
    FlushOne();
}

}  // namespace OGL