#include "frontends/sdl/imgui/image.h"

#ifdef GL_UNPACK_ROW_LENGTH
// GLES3: defined in gl3.h
#define UGL_UNPACK_LENGTH GL_UNPACK_ROW_LENGTH
#else
// GLES2: defined in gl2ext.h as an extension GL_EXT_unpack_subimage
#define UGL_UNPACK_LENGTH GL_UNPACK_ROW_LENGTH_EXT
#endif

namespace sa2
{

  /*
    2 extensions are used here

    ES2: GL_UNPACK_ROW_LENGTH_EXT and GL_BGRA_EXT
    ES3: GL_BGRA_EXT

    They both work on Pi3/4 and my Intel Haswell card.

    What does SDL do about it?

    GL_UNPACK_ROW_LENGTH_EXT: it uses instead texture coordinates
    GL_BGRA_EXT: it uses a shader to swap the color bytes

    For simplicity (and because it just works) here we are using these 2 extensions.
  */

  void allocateTexture(GLuint texture, size_t width, size_t height)
  {
    glBindTexture(GL_TEXTURE_2D, texture);

    const GLenum format = GL_BGRA_EXT; // this is defined in gl2ext.h and nowhere in gl3.h
    const GLenum type = GL_UNSIGNED_BYTE;
    glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, type, nullptr);

  }

  void loadTextureFromData(GLuint texture, const uint8_t * data, size_t width, size_t height, size_t pitch)
  {
    glBindTexture(GL_TEXTURE_2D, texture);
    glPixelStorei(UGL_UNPACK_LENGTH, pitch); // in pixels

    // Setup filtering parameters for display
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    const GLenum format = GL_BGRA_EXT; // this is defined in gl2ext.h and nowhere in gl3.h
    const GLenum type = GL_UNSIGNED_BYTE;
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, format, type, data);
    // reset to default state
    glPixelStorei(UGL_UNPACK_LENGTH, 0);
  }

}