/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2024, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

#include "opengl-precomp.h"  // Precompiled header
//
#include <mrpt/core/get_env.h>
#include <mrpt/core/lock_helper.h>
#include <mrpt/opengl/Texture.h>
#include <mrpt/opengl/opengl_api.h>

#include <iostream>
#include <mutex>
#include <set>

using namespace mrpt::opengl;

const bool MRPT_OPENGL_VERBOSE = mrpt::get_env<bool>("MRPT_OPENGL_VERBOSE", false);

// Whether to profile memory allocations:
// #define TEXTUREOBJ_PROFILE_MEM_ALLOC

// Whether to use a memory pool for the texture buffer:
#define TEXTUREOBJ_USE_MEMPOOL

#ifdef TEXTUREOBJ_USE_MEMPOOL
#include <mrpt/system/CGenericMemoryPool.h>
#endif

void Texture::unloadTexture()
{
  m_tex.run_on_all(
      [](std::optional<texture_name_unit_t>& tnu)
      {
        if (!tnu) return;
        releaseTextureName(tnu.value().name);
        tnu.reset();
      });
}

/** This class is a workaround to crashes and memory leaks caused by not
 * reserving and freeing opengl textures from the same thread. */
class TextureResourceHandler
{
 public:
  static TextureResourceHandler& Instance()
  {
    static TextureResourceHandler o;
    return o;
  }

  /// Return [textureName, textureUnit]
  texture_name_t generateTextureID()
  {
#if MRPT_HAS_OPENGL_GLUT || MRPT_HAS_EGL
    auto lck = mrpt::lockHelper(m_texturesMtx);

    processDestroyQueue();

    // Create one OpenGL texture
    GLuint textureID;
    glGenTextures(1, &textureID);
    CHECK_OPENGL_ERROR_IN_DEBUG();
    m_textureReservedFrom[textureID] = std::this_thread::get_id();

    if (MRPT_OPENGL_VERBOSE)
      std::cout << "[mrpt generateTextureID] textureName:" << textureID << std::endl;

    return textureID;
#else
    THROW_EXCEPTION("This function needs OpenGL");
#endif
  }

  void releaseTextureID(unsigned int texName)
  {
#if MRPT_HAS_OPENGL_GLUT || MRPT_HAS_EGL
    MRPT_START
    auto lck = mrpt::lockHelper(m_texturesMtx);

    if (MRPT_OPENGL_VERBOSE)
      std::cout << "[mrpt releaseTextureID] textureName: " << texName << std::endl;

    m_destroyQueue[m_textureReservedFrom.at(texName)].push_back(texName);
    processDestroyQueue();
    MRPT_END
#endif
  }

 private:
  TextureResourceHandler()
  {
#if MRPT_HAS_OPENGL_GLUT || MRPT_HAS_EGL
    glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &m_maxTextureUnits);
    if (MRPT_OPENGL_VERBOSE)
      std::cout << "[mrpt TextureResourceHandler] maxTextureUnits:" << m_maxTextureUnits
                << std::endl;
#endif
  }

  void processDestroyQueue()
  {
#if MRPT_HAS_OPENGL_GLUT || MRPT_HAS_EGL
    if (auto itLst = m_destroyQueue.find(std::this_thread::get_id()); itLst != m_destroyQueue.end())
    {
      auto& lst = itLst->second;
      glDeleteTextures(lst.size(), lst.data());
      CHECK_OPENGL_ERROR_IN_DEBUG();
      lst.clear();
    }
    if (MRPT_OPENGL_VERBOSE)
    {
      std::cout << "[mrpt processDestroyQueue] threadId=" << std::this_thread::get_id()
                << ". At output: ";
      for (const auto& lst : m_destroyQueue)
        std::cout << "[" << lst.first << "]=" << lst.second.size() << " ";
    }
#endif
  }

#if MRPT_HAS_OPENGL_GLUT || MRPT_HAS_EGL
  std::mutex m_texturesMtx;
  std::map<GLuint, std::thread::id> m_textureReservedFrom;
  std::map<std::thread::id, std::vector<GLuint>> m_destroyQueue;
  GLint m_maxTextureUnits;
#endif
};

/// Returns: [texture name, texture unit]
texture_name_t mrpt::opengl::getNewTextureNumber()
{
  return TextureResourceHandler::Instance().generateTextureID();
}

void mrpt::opengl::releaseTextureName(const texture_name_t& t)
{
  TextureResourceHandler::Instance().releaseTextureID(t);
}

bool Texture::initialized() const
{
  // already assigned an ID?
  return m_tex.get().has_value();
}

void Texture::assignImage2D(const mrpt::img::CImage& rgb, const Options& o, int textureUnit)
{
  try
  {
    internalAssignImage_2D(&rgb, nullptr, o, textureUnit);
  }
  catch (std::exception& e)
  {
    THROW_EXCEPTION_FMT("Error assigning texture: %s", e.what());
  }
}

void Texture::assignImage2D(
    const mrpt::img::CImage& rgb, const mrpt::img::CImage& alpha, const Options& o, int textureUnit)
{
  try
  {
    internalAssignImage_2D(&rgb, &alpha, o, textureUnit);
  }
  catch (std::exception& e)
  {
    THROW_EXCEPTION_FMT("Error assigning texture: %s", e.what());
  }
}

// Data types for memory pooling CRenderizableShaderTexturedTriangles:
#ifdef TEXTUREOBJ_USE_MEMPOOL

struct CRenderizableShaderTexturedTriangles_MemPoolParams
{
  /** size of the vector<unsigned char> */
  size_t len = 0;

  inline bool isSuitable(const CRenderizableShaderTexturedTriangles_MemPoolParams& req) const
  {
    return len == req.len;
  }
};
struct CRenderizableShaderTexturedTriangles_MemPoolData
{
  std::vector<uint8_t> data;
};

using TMyMemPool = mrpt::system::CGenericMemoryPool<
    CRenderizableShaderTexturedTriangles_MemPoolParams,
    CRenderizableShaderTexturedTriangles_MemPoolData>;
#endif

// Auxiliary function for loadTextureInOpenGL(): reserve memory and return
// 16byte aligned starting point within it:
namespace
{
unsigned char* reserveDataBuffer(size_t len, std::vector<uint8_t>& data)
{
#ifdef TEXTUREOBJ_USE_MEMPOOL
  TMyMemPool* pool = TMyMemPool::getInstance();
  if (pool)
  {
    CRenderizableShaderTexturedTriangles_MemPoolParams mem_params;
    mem_params.len = len;

    CRenderizableShaderTexturedTriangles_MemPoolData* mem_block = pool->request_memory(mem_params);
    if (mem_block)
    {
      // Recover the memory block via a swap:
      data.swap(mem_block->data);
      delete mem_block;
    }
  }
#endif
  data.resize(len);
  void* ptr = &data[0];
  size_t space = len;
  return reinterpret_cast<unsigned char*>(std::align(16, 1 /*dummy size*/, ptr, space));
}
}  // namespace

void Texture::internalAssignImage_2D(
    const mrpt::img::CImage* in_rgb,
    const mrpt::img::CImage* in_alpha,
    const Options& o,
    int textureUnit)
{
#if MRPT_HAS_OPENGL_GLUT || MRPT_HAS_EGL
  unsigned char* dataAligned = nullptr;
  std::vector<uint8_t> data;

#ifdef TEXTUREOBJ_PROFILE_MEM_ALLOC
  static mrpt::system::CTimeLogger tim;
#endif

  ASSERT_(in_rgb);

  in_rgb->forceLoad();  // just in case they are lazy-load imgs
  if (in_alpha) in_alpha->forceLoad();

  ASSERT_(in_rgb->getPixelDepth() == mrpt::img::PixelDepth::D8U);

  // Shallow copy of the images, for the case we need to downsample them
  // below:
  mrpt::img::CImage rgb(*in_rgb, mrpt::img::SHALLOW_COPY);
  mrpt::img::CImage alpha;
  if (in_alpha) alpha = mrpt::img::CImage(*in_alpha, mrpt::img::SHALLOW_COPY);

  // allocate texture names:
  get() = getNewTextureNumber();
  get()->unit = textureUnit;

  // activate the texture unit first before binding texture
  bindAsTexture2D();

  // when texture area is small, linear interpolation:
  if (o.generateMipMaps)
  {
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_LINEAR);
    CHECK_OPENGL_ERROR_IN_DEBUG();
  }
  else
  {
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    CHECK_OPENGL_ERROR_IN_DEBUG();
  }

  // when texture area is large:
  glTexParameterf(
      GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, o.magnifyLinearFilter ? GL_LINEAR : GL_NEAREST);
  CHECK_OPENGL_ERROR_IN_DEBUG();

  // if wrap is true, the texture wraps over at the edges (repeat)
  //       ... false, the texture ends at the edges (clamp)
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  CHECK_OPENGL_ERROR_IN_DEBUG();

  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  CHECK_OPENGL_ERROR_IN_DEBUG();
  MRPT_TODO("wrap options?");

  // Assure that the images do not overpass the maximum dimensions allowed
  // by OpenGL:
  // ------------------------------------------------------------------------------------
  GLint texSize;
  glGetIntegerv(GL_MAX_TEXTURE_SIZE, &texSize);
  while (rgb.getHeight() > (unsigned int)texSize || rgb.getWidth() > (unsigned int)texSize)
  {
    static bool warningEmitted = false;
    if (!warningEmitted)
    {
      warningEmitted = true;
      std::cerr << "[mrpt::opengl::CRenderizableShaderTexturedTriangles] "
                   "**PERFORMACE WARNING**:\n"
                << " Downsampling texture image of size " << rgb.getWidth() << "x"
                << rgb.getHeight()
                << " since maximum allowed OpenGL texture size "
                   "(GL_MAX_TEXTURE_SIZE) is "
                << texSize << "\n";
    }

    rgb = rgb.scaleHalf(mrpt::img::IMG_INTERP_LINEAR);
    if (in_alpha) alpha = alpha.scaleHalf(mrpt::img::IMG_INTERP_LINEAR);
  }

  const int width = rgb.getWidth();
  const int height = rgb.getHeight();

#ifdef TEXTUREOBJ_PROFILE_MEM_ALLOC
  {
    const std::string sSec = mrpt::format(
        "opengl_texture: load %ix%i %s %stransp", width, height, rgb->isColor() ? "RGB" : "BW",
        m_enableTransparency ? "" : "no ");
    tim.enter(sSec.c_str());
  }
#endif

  // GL_LUMINANCE and GL_LUMINANCE_ALPHA were removed in OpenGL 3.1
  // Convert grayscale images into color:
  if (!rgb.isColor()) rgb = rgb.colorImage();

  // ----------------------------------------------
  // Color texture WITH alpha channel
  // ----------------------------------------------
  if (o.enableTransparency)
  {
    ASSERT_(!alpha.isColor());
    ASSERT_EQUAL_(alpha.getWidth(), rgb.getWidth());
    ASSERT_EQUAL_(alpha.getHeight(), rgb.getHeight());

#ifdef TEXTUREOBJ_PROFILE_MEM_ALLOC
    const std::string sSec =
        mrpt::format("opengl_texture_alloc %ix%i (color,trans)", width, height);
    tim.enter(sSec.c_str());
#endif

    dataAligned = reserveDataBuffer(height * width * 4 + 512, data);

#ifdef TEXTUREOBJ_PROFILE_MEM_ALLOC
    tim.leave(sSec.c_str());
#endif

    for (int y = 0; y < height; y++)
    {
      unsigned char* ptrSrcCol = rgb(0, y, 0);
      unsigned char* ptrSrcAlfa = alpha(0, y);
      unsigned char* ptr = dataAligned + y * width * 4;

      for (int x = 0; x < width; x++)
      {
        *ptr++ = *ptrSrcCol++;
        *ptr++ = *ptrSrcCol++;
        *ptr++ = *ptrSrcCol++;
        *ptr++ = *ptrSrcAlfa++;
      }
    }

    // Prepare image data types:
    const GLenum img_type = GL_UNSIGNED_BYTE;
    // Reverse RGB <-> BGR order?
    const bool is_RGB_order = (rgb.getChannelsOrder() == std::string("RGB"));
    const GLenum img_format = (is_RGB_order ? GL_RGBA : GL_BGRA);

    // Send image data to OpenGL:
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glPixelStorei(GL_UNPACK_ROW_LENGTH, width);
    glTexImage2D(
        GL_TEXTURE_2D, 0 /*level*/, GL_RGBA8 /* RGB components */, width, height, 0 /*border*/,
        img_format, img_type, dataAligned);
    CHECK_OPENGL_ERROR_IN_DEBUG();
    glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);  // Reset
    CHECK_OPENGL_ERROR_IN_DEBUG();

  }  // End of color texture WITH trans.
  else
  {
    // Color texture without transparency,
    // or with integrated RGBA alpha channel
    // --------------------------------------
    // Prepare image data types:
    const GLenum img_type = GL_UNSIGNED_BYTE;
    const int nBytesPerPixel = rgb.channelCount();
    // Reverse RGB <-> BGR order?
    const bool is_RGB_order = (rgb.getChannelsOrder() == std::string("RGB"));
    const GLenum img_format = [=]()
    {
      switch (nBytesPerPixel)
      {
        case 1:
          return GL_LUMINANCE;
        case 3:
          return (is_RGB_order ? GL_RGB : GL_BGR);
        case 4:
          return GL_BGRA;
      };
      THROW_EXCEPTION("Invalid texture image channel count.");
    }();

    // Send image data to OpenGL:
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    CHECK_OPENGL_ERROR_IN_DEBUG();
    glPixelStorei(GL_UNPACK_ROW_LENGTH, rgb.getRowStride() / nBytesPerPixel);
    CHECK_OPENGL_ERROR_IN_DEBUG();
    glTexImage2D(
        GL_TEXTURE_2D, 0 /*level*/, nBytesPerPixel == 3 ? GL_RGB8 : GL_RGBA8 /* RGB components */,
        width, height, 0 /*border*/, img_format, img_type, rgb.ptrLine<uint8_t>(0));
    CHECK_OPENGL_ERROR_IN_DEBUG();
    glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);  // Reset
    CHECK_OPENGL_ERROR_IN_DEBUG();
  }  // End of color texture WITHOUT trans.

  if (o.generateMipMaps)
  {
    glGenerateMipmap(GL_TEXTURE_2D);
    CHECK_OPENGL_ERROR_IN_DEBUG();
  }

  // Was: m_texture_is_loaded = true;
  // Now this situation is represented by the optional m_glTexture having
  // a valid value.

#ifdef TEXTUREOBJ_PROFILE_MEM_ALLOC
  {
    const std::string sSec = mrpt::format(
        "opengl_texture: load %ix%i %s %stransp", width, height, rgb->isColor() ? "RGB" : "BW",
        m_enableTransparency ? "" : "no ");
    tim.leave(sSec.c_str());
  }
#endif

#ifdef TEXTUREOBJ_USE_MEMPOOL
  // Before freeing the buffer in "data", donate my memory to the pool:
  if (!data.empty())
  {
    TMyMemPool* pool = TMyMemPool::getInstance();
    if (pool)
    {
      CRenderizableShaderTexturedTriangles_MemPoolParams mem_params;
      mem_params.len = data.size();

      auto* mem_block = new CRenderizableShaderTexturedTriangles_MemPoolData();
      data.swap(mem_block->data);

      pool->dump_to_pool(mem_params, mem_block);
    }
  }
#endif
#endif
}

void Texture::bindAsTexture2D()
{
#if MRPT_HAS_OPENGL_GLUT || MRPT_HAS_EGL
  glActiveTexture(GL_TEXTURE0 + get()->unit);
  glBindTexture(GL_TEXTURE_2D, get()->name);
  CHECK_OPENGL_ERROR_IN_DEBUG();
#endif
}

void Texture::bindAsCubeTexture()
{
#if MRPT_HAS_OPENGL_GLUT || MRPT_HAS_EGL
  glActiveTexture(GL_TEXTURE0 + get()->unit);
  glBindTexture(GL_TEXTURE_CUBE_MAP, get()->name);
  CHECK_OPENGL_ERROR_IN_DEBUG();
#endif
}

void Texture::assignCubeImages(const std::array<mrpt::img::CImage, 6>& imgs, int textureUnit)
{
#if MRPT_HAS_OPENGL_GLUT || MRPT_HAS_EGL

  // just in case they are lazy-load imgs
  for (auto& im : imgs)
  {
    im.forceLoad();
    ASSERT_(im.getPixelDepth() == mrpt::img::PixelDepth::D8U);
    ASSERT_(im.isColor());
  }

  // allocate texture "name" (ID):
  get() = getNewTextureNumber();

  // activate the texture unit first before binding texture
  bindAsCubeTexture();

  glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  // Special "wrap" for cube skybox textures:
  glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
  CHECK_OPENGL_ERROR_IN_DEBUG();

  // Check max hardware-allowed texture size:
  {
    GLint maxTexSize;
    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxTexSize);
    ASSERT_LE_(imgs[0].getHeight(), (unsigned int)maxTexSize);
    ASSERT_LE_(imgs[0].getWidth(), (unsigned int)maxTexSize);
  }

  for (int face = 0; face < 6; face++)
  {
    const auto& rgb = imgs.at(face);

    const int width = rgb.getWidth();
    const int height = rgb.getHeight();

    // Format: color texture without transparency, or with integrated
    // RGBA alpha channel

    // Prepare image data types:
    const GLenum img_type = GL_UNSIGNED_BYTE;
    const int nBytesPerPixel = rgb.channelCount();
    // Reverse RGB <-> BGR order?
    const bool is_RGB_order = (rgb.getChannelsOrder() == std::string("RGB"));
    const GLenum img_format = [=]()
    {
      switch (nBytesPerPixel)
      {
        case 1:
          return GL_LUMINANCE;
        case 3:
          return (is_RGB_order ? GL_RGB : GL_BGR);
        case 4:
          return GL_BGRA;
      };
      THROW_EXCEPTION("Invalid texture image channel count.");
    }();

    // Send image data to OpenGL:
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    CHECK_OPENGL_ERROR_IN_DEBUG();
    glPixelStorei(GL_UNPACK_ROW_LENGTH, rgb.getRowStride() / nBytesPerPixel);
    CHECK_OPENGL_ERROR_IN_DEBUG();
    glTexImage2D(
        GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, 0 /*level*/,
        nBytesPerPixel == 3 ? GL_RGB8 : GL_RGBA8 /* RGB components */, width, height, 0 /*border*/,
        img_format, img_type, rgb.ptrLine<uint8_t>(0));
    CHECK_OPENGL_ERROR_IN_DEBUG();
    glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);  // Reset
    CHECK_OPENGL_ERROR_IN_DEBUG();

  }  // end for each "face"

#endif
}
