#ifndef ALARMA_H
#define ALARMA_H

#include <cerrno>
#include <csignal> // signal
#include <system_error>

class signal_handler
{
public:
    typedef void (*handler_t)(int);

    signal_handler(int s, handler_t handler): signal_number(s)
    {
        old_handler = signal(signal_number, handler);
    }
    ~signal_handler() { signal(signal_number, old_handler); }

private:
    int signal_number;
    handler_t old_handler;
};

// struct sigaction
// {
//     void (*sa_handler)(int);
//     void (*sa_sigaction)(int, siginfo_t *, void *);
//     sigset_t sa_mask;
//     int sa_flags;
//     void (*sa_restorer)(void);
// };

class signal_set
{
public:
    typedef void (*handler_t)(int);

    signal_set(int s, handler_t handler, int flags = 0)
        : signal_number(s), installed(false)
    {
        struct sigaction new_action;
        new_action.sa_handler = handler;
        new_action.sa_flags = flags;
        sigemptyset(&new_action.sa_mask);

        if (sigaction(signal_number, &new_action, &old_action) == -1)
            throw std::system_error(errno, std::generic_category(),
                                    "sigaction install failed");

        installed = true;
    }

    ~signal_set()
    {
        if (installed)
            sigaction(signal_number, &old_action, nullptr);
    }

    signal_set(const signal_set &) = delete;
    signal_set &operator=(const signal_set &) = delete;

private:
    int signal_number;
    struct sigaction old_action;
    bool installed;
};

#endif // ALARMA_H