#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <png.h>

#include "PNGWriter.h"

using namespace std;

//functions needed to use  c++ streams with libpng
static void stream_write_data(png_structp, png_bytep, png_size_t);
static void stream_flush_data(png_structp);

namespace tlprender {
  PNGWriter::PNGWriter(const GLubyte *imagebuffer, const int width, const int height):
    ImageWriter(imagebuffer, width, height)
  {}

  bool PNGWriter::writeImage(std::ostream &os) const
  {
    png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png_ptr) {
      return false;
    }
  
    png_infop info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
      png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
      return false;
    }

#ifdef PNG_SETJMP_SUPPORTED
    if (setjmp(png_jmpbuf(png_ptr)))
#endif
      {
        png_destroy_write_struct(&png_ptr, &info_ptr);
        return false;
      }

    png_set_write_fn(png_ptr, &os, &stream_write_data, &stream_flush_data);
    /* PNG Header */
    png_set_IHDR(png_ptr, info_ptr, width, height, 8,
                 PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
                 PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);

    int num_text = 0 + titleState + softwareState + sourceState + layoutState + commentState;
    png_text *text_ptr = new png_text[num_text];
    int i=0;
    if (titleState) {
      text_ptr[i].compression = PNG_TEXT_COMPRESSION_NONE;
      text_ptr[i].key = "Title";
      text_ptr[i].text = const_cast<char *>(title.c_str());
      ++i;
    }
    if (softwareState) {
      text_ptr[i].compression = PNG_TEXT_COMPRESSION_NONE;
      text_ptr[i].key = "Software";
      text_ptr[i].text = const_cast<char *>(software.c_str());
      ++i;
    }
    if (sourceState) {
      text_ptr[i].compression = PNG_TEXT_COMPRESSION_NONE;
      text_ptr[i].key = "Source";
      text_ptr[i].text = const_cast<char *>(source.c_str());
      ++i;
    }
    if (layoutState) {
      text_ptr[i].compression = PNG_TEXT_COMPRESSION_NONE;
      text_ptr[i].key = "Layout";
      text_ptr[i].text = const_cast<char *>(layout.c_str());
    }
    if (commentState) {
      text_ptr[i].compression = PNG_TEXT_COMPRESSION_NONE;
      text_ptr[i].key = "Comment";
      text_ptr[i].text = const_cast<char *>(comment.c_str());
      ++i;
    }
    
    png_set_text(png_ptr, info_ptr, text_ptr, num_text);

    png_write_info(png_ptr, info_ptr);
    delete text_ptr;
    
    /* Image */
    for (int i=height-1; i>=0; --i) {
      png_bytep rowp = (png_bytep) buffer + (width * i * 4 * sizeof(GLubyte));
      png_write_row(png_ptr, rowp);
    }

    /* PNG EOF */
    png_write_end(png_ptr, info_ptr);
    png_destroy_write_struct(&png_ptr, &info_ptr);
    return true;
  }
}

static void stream_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
  ostream *os = (ostream *)png_get_io_ptr(png_ptr);
  for(png_size_t i=0; i<length; ++i) {
    (*os) << data[i];
  }
}

static void stream_flush_data(png_structp png_ptr)
{
  ostream *os = (ostream *)png_get_io_ptr(png_ptr);
  os->flush();
}