#include <iostream>
#include <string>
#include <sstream>
#include <boost/endian/arithmetic.hpp>
#include <boost/asio.hpp>

namespace asio = boost::asio;
namespace endian = boost::endian;

int readVarInt(int32_t& output, unsigned char* buffer, size_t buflen)
{
    output = 0;
    int v2 = 0;
    signed char v3;
    do
    {
        if (v2 >= buflen) break;
        v3 = buffer[v2];
        output |= (v3 & 127) << (v2++ * 7);
        if (v2 > 5) return v2;
    } while ((v3 & 128) == 128);
    return v2;
}

int writeVarInt(int32_t input, unsigned char* buffer)
{
    int i = 0;
    while ((input & -128) != 0)
    {
        buffer[i++] = (input & 127) | 128;
        input >>= 7;
    }
    buffer[i++] = input;
    return i;
}

void writeVarIntToStream(std::ostringstream& stream, std::int32_t number)
{
    unsigned char buffer[8];
    int len = writeVarInt(number, buffer);
    stream.write(reinterpret_cast<const char*>(buffer), len);
}

int main(int argc, char** argv)
{
    if (argc != 3)
    {
        std::cerr << "Usage: host port";
        return 1;
    }

    std::string host(argv[1]);
    int port;
    try
    {
        port = std::stoi(argv[2]);
    }
    catch (std::exception&)
    {
        std::cerr<< "Invalid port number: " << argv[2];
        return 2;
    }

    std::ostringstream stream(std::ios::binary);

    writeVarIntToStream(stream, 0);
    writeVarIntToStream(stream, 47);
    writeVarIntToStream(stream, static_cast<int>(host.size()));
    stream.write(host.data(), host.size());
    endian::big_uint16_t portt(port);
    stream.write(reinterpret_cast<const char*>(&portt), 2);
    writeVarIntToStream(stream, 1);

    std::string fin = stream.str();
    stream.str("");
    writeVarIntToStream(stream, static_cast<int>(fin.size()));
    stream.write(fin.data(), fin.size());

    fin = stream.str();

    try
    {
        asio::io_service io;
        asio::ip::tcp::iostream con(host, std::to_string(port));
        con.expires_from_now(boost::posix_time::seconds(20));

        if (!con)
            std::cerr << "Error: " << con.error().message() << "\n";

        con << stream.str();

        std::string str;
        con >> str;
    }
    catch (std::exception& e)
    {
        std::cerr << e.what() << '\n';
    }

    return 0;
}