import <iostream>;
import <vector>;
import <string>;
import <random>;
import <chrono>;
import <thread>;
import <cmath>;
import <cstdlib>;
import <algorithm>;
#include <locale>

struct Snowflake {
    int x, y;               // position
    int speed;              // frames per movement
    int counter;            // for speed timing
    std::string symbol;     // Unicode snowflake
    double brightness;      // simulate fade-in/out
};

int main() {
    std::setlocale(LC_ALL, ""); // enable UTF-8 output
    const int width = 80;
    const int height = 24;
    const int numFlakes = 120;

    std::vector<Snowflake> flakes(numFlakes);

    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_int_distribution<> xDist(0, width-1);
    std::uniform_int_distribution<> yDist(0, height-1);
    std::uniform_int_distribution<> speedDist(1,4);
    std::uniform_int_distribution<> symbolDist(0,3);
    std::uniform_real_distribution<> brightnessDist(0.3,1.0);
    std::uniform_int_distribution<> driftDist(-1,1);

    const std::vector<std::string> symbols = {"*", "❄", "❅", "❆"};

    for (auto &f : flakes) {
        f.x = xDist(gen);
        f.y = yDist(gen);
        f.speed = speedDist(gen);
        f.counter = 0;
        f.symbol = symbols[symbolDist(gen)];
        f.brightness = brightnessDist(gen);
    }

    double wind = 0.0;
    double targetWind = 0.0;

    std::uniform_real_distribution<> windDist(-0.3,0.3);

    while (true) {
        // gradually change wind
        targetWind += windDist(gen) * 0.05;
        wind += (targetWind - wind) * 0.05;

        // clear screen
        #ifdef _WIN32
            std::system("cls");
        #else
            std::cout << "\x1B[2J\x1B[H";
        #endif

        // frame buffer
        std::vector<std::string> frame(height, std::string(width,' '));

        // update flakes
        for (auto &f : flakes) {
            f.counter++;
            if(f.counter >= f.speed) {
                f.y++;
                f.x += static_cast<int>(std::round(driftDist(gen) + wind));
                if(f.x < 0) f.x = 0;
                if(f.x >= width) f.x = width-1;
                if(f.y >= height) {
                    f.y = 0;
                    f.x = xDist(gen);
                    f.symbol = symbols[symbolDist(gen)];
                    f.brightness = brightnessDist(gen);
                    f.speed = speedDist(gen);
                }
                f.counter = 0;
            }

            // simulate fade: dim flakes near top
            int color = static_cast<int>(232 + f.brightness * 23); // grayscale ANSI
            std::cout << "\033[" << f.y+1 << ";" << f.x+1 << "H"
                      << "\033[38;5;" << color << "m" << f.symbol;
        }

        std::cout << "\033[0m"; // reset color
        std::cout.flush();

        std::this_thread::sleep_for(std::chrono::milliseconds(80));
    }

    return 0;
}