#include <cmath>
#include <cstdint>
#include <cstdio>
#include <functional>
#include <memory>
#include <random>
#include <CImg.h>

using cimg_library::CImg;
using cimg_library::CImgDisplay;

struct Rectangle {
    int x, y, w, h;
};

static double distance(const CImg<std::uint8_t> &original, const CImg<std::uint8_t> &img,
                       Rectangle bounds)
{
    int sum = 0;

    for (int c = 0; c < 3; ++c) {
        for (int y = 0; y < bounds.h; ++y) {
            for (int x = 0; x < bounds.w; ++x) {
                std::uint8_t orig_val = original(x + bounds.x, y + bounds.y, 0, c);
                std::uint8_t img_val = img(x + bounds.x, y + bounds.y, 0, c);

                std::int16_t diff = img_val - orig_val;
                sum += diff * diff;
            }
        }
    }

    return std::sqrt(sum) / bounds.w * bounds.h;
}

static double distance(const CImg<std::uint8_t> &original, std::uint8_t *colour,
                       Rectangle bounds)
{
    int sum = 0;

    for (int c = 0; c < 3; ++c) {
        for (int y = 0; y < bounds.h; ++y) {
            for (int x = 0; x < bounds.w; ++x) {
                std::uint8_t orig_val = original(x + bounds.x, y + bounds.y, 0, c);
                std::uint8_t img_val = colour[c];

                std::int16_t diff = img_val - orig_val;
                sum += diff * diff;
            }
        }
    }

    return std::sqrt(sum) / bounds.w * bounds.h;
}

int main()
{
    std::random_device rd;
    std::mt19937 x_gen(rd());
    std::mt19937 y_gen(rd());
    std::mt19937 dim_gen(rd());

    CImg<std::uint8_t> original("test.png");
    CImg<std::uint8_t> img(original.width(), original.height(), 1, 3, 255);

    std::uniform_int_distribution<int> x_distribution(0, original.width() - 16);
    std::uniform_int_distribution<int> y_distribution(0, original.height() - 16);
    std::uniform_int_distribution<int> dim_distribution(5, 15);

    auto x_rand = std::bind(x_distribution, x_gen);
    auto y_rand = std::bind(y_distribution, y_gen);
    auto dim_rand = std::bind(dim_distribution, dim_gen);

    std::uint8_t colour[3];

    CImgDisplay disp(img, "randompic");

    unsigned long long iterations = 0;
    while (!disp.is_closed()) {
        for (int i = 0; i < 100000; ++i) {
            iterations++;
            Rectangle rect {x_rand(), y_rand(), dim_rand(), dim_rand()};
            colour[0] = original(x_rand(), y_rand(), 0, 0);
            colour[1] = original(x_rand(), y_rand(), 0, 1);
            colour[2] = original(x_rand(), y_rand(), 0, 2);

            if (distance(original, img, rect) > distance(original, colour, rect)) {
                img.draw_rectangle(rect.x, rect.y, rect.x + rect.w - 1, rect.y + rect.h - 1, colour);
            }
        }
        disp.display(img);
        std::printf("%llu\n", iterations);
    }

    return 0;
}