/*
   render/png.cc
   This file is part of the Osirion project and is distributed under
   the terms of the GNU General Public License version 2
*/

/*
Notes:

http://www.zarb.org/~gc/html/libpng.html

*/

#include <string.h>
#include <png.h>

#include <iostream>

#include "filesystem/filesystem.h"
#include "render/pngfile.h"
#include "sys/sys.h"

namespace render {

Image *PNG::load(const char *filename)
{
	Image *image = 0;

	if (!filename)
		return 0;

	filesystem::File *png_file = filesystem::open(filename);
	if (!png_file) {
		//con_warn << "Could not open " << filename << std::endl;
		return 0;
	}

	png_byte header[8];
	memset(header, 0, sizeof(header));

	if (!png_file->read(header, 8)) {
		con_warn << "Error reading " << filename << std::endl;
		filesystem::close(png_file);
		return 0;
	}
	if (png_sig_cmp(header, 0, 8)) {
		con_warn << "Error reading " << filename << ": not a PNG file!" << std::endl;
		filesystem::close(png_file);
		return 0;
	}

	png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png_ptr) {
		con_warn << "Error reading " << filename << ": png_create_read_struct failed!" << std::endl;
		filesystem::close(png_file);
		return 0;
	}

	png_infop info_ptr = png_create_info_struct(png_ptr);
        if (!info_ptr) {
	con_warn << "Error reading " << filename << ": png_create_info_struct failed!" << std::endl;
		filesystem::close(png_file);
		return 0;
	}
        if (setjmp(png_jmpbuf(png_ptr))) {
               	con_warn << "Error reading " << filename << ": error during init_io!" << std::endl;
		filesystem::close(png_file);
		return 0;
	}

	/* read the PNG header */
	png_init_io(png_ptr, png_file->handle());
        png_set_sig_bytes(png_ptr, 8);

        png_read_info(png_ptr, info_ptr);

        int png_width = info_ptr->width;
        int png_height = info_ptr->height;
        //int png_color_type = info_ptr->color_type;
        int png_depth = info_ptr->bit_depth;

        //int number_of_passes = png_set_interlace_handling(png_ptr);
	png_set_interlace_handling(png_ptr);
        png_read_update_info(png_ptr, info_ptr);
	
	if (png_depth != 8) {
		con_warn << "Error reading " << filename << ": bits per channel must be 8!" << std::endl;
		filesystem::close(png_file);
		return 0;
	}

	unsigned int channels =  info_ptr->rowbytes / png_width;
	image = new Image(png_width, png_height, channels);

	/* read image data */
        if (setjmp(png_jmpbuf(png_ptr))) {
		con_warn << "Error reading " << filename << std::endl;
		filesystem::close(png_file);
		delete image;
		return 0;
	}

	png_bytep row_pointers[png_height];

        for (size_t i=0; i < (size_t)png_height; i++)
                row_pointers[i] = (png_bytep) (*image)[i * info_ptr->rowbytes];

        png_read_image(png_ptr, row_pointers);

        filesystem::close(png_file);

	con_debug << "  " << filename << " " << png_width << "x" << png_height << "x" << channels * png_depth << "bpp" << std::endl;

	return image;
}

void PNG::save(const char *filename, Image & image)
{
	con_warn << "PNG::save stub" << std::endl;
}

}