#include <iostream>
#include <fstream>
#include <png++/png.hpp>

#define CACHESIZE 4096u //must be lower than 2^13
#define __CACHESIZE (CACHESIZE*4u) //Do not edit

int main(int argc, char *argv[])
{
        if (argc < 3)
        {
                std::cerr << "USAGE: " << argv[0] << " INPUT.PNG OUTPUT" << std::endl;
                exit(EXIT_FAILURE);
        }

        png::image< png::rgb_pixel > input(argv[1]);

        std::ofstream bitmap(argv[2]);
        uint32_t width, height, x, y;
        width = input.get_width();
        height = input.get_height();
        x = y = 0;
        size_t i = 0;

        bitmap << width << " " << height << " ";

        char* cache = new char[__CACHESIZE];
        while (i < width*height*4)
        {
                x = ((uint32_t) i/4 ) % width;
                y = (uint32_t)(i/4/width);

                cache[(i+1)%__CACHESIZE] = input[y][x].red;
                cache[(i+0)%__CACHESIZE] = input[y][x].green;
                cache[(i+3)%__CACHESIZE] = input[y][x].blue;
                cache[(i+2)%__CACHESIZE] = 255;

                i+=4;

                if (i % __CACHESIZE == 0) //Write
                        bitmap.write(cache, __CACHESIZE);
        }
        if (i % __CACHESIZE != 0) //Write what has not been written
                bitmap.write(cache, width*height*4 % __CACHESIZE);

        delete[] cache;
        bitmap.close();


        return EXIT_SUCCESS;
}