/*
   render/pngfile.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 "png.h"

#include <string.h>

#include <iostream>

#include "sys/sys.h"
#include "filesystem/filesystem.h"
#include "render/pngfile.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);
		png_destroy_read_struct(&png_ptr, 0, 0);
		return 0;
	}
	if (setjmp(png_jmpbuf(png_ptr))) {
		con_warn << "Error reading " << filename << ": error during init_io!" << std::endl;
		filesystem::close(png_file);
		png_destroy_read_struct(&png_ptr, &info_ptr, 0);
		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 = png_get_image_width(png_ptr, info_ptr);		// image width
	int png_height = png_get_image_height(png_ptr, info_ptr);	// image height
	int png_depth = png_get_bit_depth(png_ptr, info_ptr);		// bits per channel
	int png_channels = png_get_channels(png_ptr, info_ptr);		// channels
	int png_rowbytes = png_get_rowbytes(png_ptr, info_ptr);		// bytes per row

	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);
		png_destroy_read_struct(&png_ptr, &info_ptr, 0);
		return 0;
	}

	image = new Image(png_width, png_height, png_channels);

	/* read image data */
	if (setjmp(png_jmpbuf(png_ptr))) {
		con_warn << "Error reading " << filename << std::endl;
		filesystem::close(png_file);
		delete image;
		png_destroy_read_struct(&png_ptr, &info_ptr, 0);
		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 * png_rowbytes];

	// read pixel data
	png_read_image(png_ptr, row_pointers);

	filesystem::close(png_file);
	png_destroy_read_struct(&png_ptr, &info_ptr, 0);

	con_debug << "  " << filename << " " << image->width() << "x" << image->height() << "x" << image->bpp() << "bpp" << std::endl;
	return image;
}

void PNG::save(const char *filename, Image & image)
{

	FILE *png_file = fopen(filename, "wb");
	if (!png_file) {
		con_warn << "Could not write " << filename << std::endl;
		return;
	}

	png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png_ptr) {
		fclose(png_file);
		con_warn << "Error writing " << filename << ": png_create_write_struct failed!" << std::endl;
		return;
	}

	png_infop info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr) {
		con_warn << "Error writing " << filename << ": png_create_info_struct failed!" << std::endl;
		fclose(png_file);
		png_destroy_write_struct(&png_ptr, 0);
		return;
	}

	if (setjmp(png_jmpbuf(png_ptr))) {
		con_warn << "Error reading " << filename << ": error during init_io!" << std::endl;
		fclose(png_file);
		png_destroy_write_struct(&png_ptr, &info_ptr);
		return;
	}

	png_init_io(png_ptr, png_file);

	/* write header */
	if (setjmp(png_jmpbuf(png_ptr))) {
		con_warn << "Error writing " << filename << ": error writing header!" << std::endl;
		fclose(png_file);
		png_destroy_write_struct(&png_ptr, &info_ptr);
		return;
	}

	png_set_IHDR(png_ptr, info_ptr, image.width(), image.height(), 8, PNG_COLOR_TYPE_RGB,
		     PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

	png_write_info(png_ptr, info_ptr);

	/* write image data */
	if (setjmp(png_jmpbuf(png_ptr))) {
		con_warn << "Error writing " << filename << ": error writing header!" << std::endl;
		fclose(png_file);
		png_destroy_write_struct(&png_ptr, &info_ptr);
		return;
	}

	png_bytep row_pointers[image.height()];

	for (size_t i = 0; i < image.height(); i++)
		row_pointers[i] = (png_bytep) image[i * image.width() * image.channels()];

	png_write_image(png_ptr, row_pointers);

	/* end write */
	if (setjmp(png_jmpbuf(png_ptr))) {
		con_warn << "Error writing " << filename << std::endl;
		fclose(png_file);
		png_destroy_write_struct(&png_ptr, &info_ptr);
		return;
	}

	png_write_end(png_ptr, NULL);

	fclose(png_file);
	png_destroy_write_struct(&png_ptr, &info_ptr);

}

}