#include <iostream>
#include <iomanip>
#include <chrono>
#include <cstring>
#include <asio.hpp>

const int NTP_PORT = 123;
const int NTP_PACKET_SIZE = 48;

void queryNTPServer(const std::string& server) {
    try {
        asio::io_context io_context;

        asio::ip::udp::resolver resolver(io_context);
        asio::ip::udp::endpoint endpoint = *resolver.resolve(server, std::to_string(NTP_PORT)).begin();

        asio::ip::udp::socket socket(io_context);
        socket.open(asio::ip::udp::v4());

        std::array<unsigned char, NTP_PACKET_SIZE> request{};
        request[0] = 0b11100011; 

        auto start_time = std::chrono::high_resolution_clock::now();

        socket.send_to(asio::buffer(request), endpoint);

        std::array<unsigned char, NTP_PACKET_SIZE> response{};
        asio::ip::udp::endpoint sender_endpoint;
        socket.receive_from(asio::buffer(response), sender_endpoint);

        auto end_time = std::chrono::high_resolution_clock::now();
        std::chrono::duration<double> ping = end_time - start_time;

        const unsigned long long NTP_TIMESTAMP_DELTA = 2208988800ULL;
        unsigned long long seconds = (static_cast<unsigned long long>(response[40]) << 24) |
                                     (static_cast<unsigned long long>(response[41]) << 16) |
                                     (static_cast<unsigned long long>(response[42]) << 8) |
                                     static_cast<unsigned long long>(response[43]);
        seconds -= NTP_TIMESTAMP_DELTA;

        std::time_t time = static_cast<std::time_t>(seconds);
        std::tm* utc_time = std::gmtime(&time);

        std::cout << "Details of " << server << "\n";
        std::cout << "Time: " << std::put_time(utc_time, "%H:%M:%S") << " UTC\n";
        std::cout << "Date: " << std::put_time(utc_time, "%Y-%m-%d") << "\n";
        std::cout << "Ping: " << std::fixed << std::setprecision(3) << ping.count() * 1000 << " ms\n";

    } catch (const std::exception& e) {
        std::cerr << "Error: " << e.what() << "\n";
    }
}

int main(int argc, char* argv[]) {
    if (argc != 2) {
        std::cerr << "Usage: " << argv[0] << " <NTP server>\n";
        return 1;
    }

    std::string server = argv[1];
    queryNTPServer(server);
    return 0;
}