#include <stdio.h>

#include <WinSock2.h>
#include <ws2tcpip.h>
#include <iphlpapi.h>

#include <vector>

struct WSA {
    WSADATA wsa;

    explicit WSA(WORD version = MAKEWORD(2, 2)) {
        int result = WSAStartup(version, &wsa);
        if (result) throw result;
    }
    ~WSA() noexcept {
        WSACleanup();
    }
};

struct Buffer {
    std::vector<char> data;

    explicit Buffer(int len):
    data(len, 0) {}

    char* get() noexcept {
        return data.data();
    }
    const char* get() const noexcept {
        return data.data();
    }

    int len() const noexcept {
        return data.size();
    }
};

struct Socket {
    enum AddrAction {
        NO_ACTION,
        CONNECT,
        BIND,
    };

    SOCKET s;
    struct sockaddr addr;

    explicit Socket(SOCKET init = INVALID_SOCKET) noexcept:
    s(init) {}
    ~Socket() noexcept {
        closesocket(s);
    }

    operator SOCKET() const noexcept {
        return s;
    }

    explicit operator bool() const noexcept {
        return is_valid();
    }
    bool is_valid() const noexcept {
        return s != INVALID_SOCKET;
    }

    void from_addrinfo(const struct addrinfo &info, AddrAction action = NO_ACTION);

    Socket accept_client() const noexcept {
        return Socket(accept(s, NULL, NULL));
    }

    void stop_send() const {
        int result = shutdown(s, SD_SEND);
        if (result == SOCKET_ERROR) throw result;
    }

    int send_data(const Buffer &data) const noexcept {
        return send(s, data.get(), data.len(), 0);
    }
    int recv_data(Buffer &data) const noexcept {
        return recv(s, data.get(), data.len(), 0);
    }
};