/**
 * @file Timer.cpp
 * @author apio (cloudapio.eu)
 * @brief Millisecond-precision timer.
 *
 * @copyright Copyright (c) 2024, the Luna authors.
 *
 */

#include <errno.h>
#include <os/EventLoop.h>
#include <os/Timer.h>

namespace os
{
    Result<OwnedPtr<Timer>> Timer::create_singleshot(unsigned int milliseconds, Action&& action)
    {
        auto timer = TRY(adopt_owned_if_nonnull(new (std::nothrow) Timer()));

        int status = timer_create(CLOCK_REALTIME, nullptr, &timer->m_timerid);
        if (status < 0) return err(errno);

        struct timespec time = { .tv_sec = milliseconds / 1000, .tv_nsec = (milliseconds % 1000) * 1'000'000 };
        struct itimerspec itimer = { .it_interval = { .tv_sec = 0, .tv_nsec = 0 }, .it_value = time };

        timer_settime(timer->m_timerid, 0, &itimer, nullptr);

        timer->m_repeating = false;
        timer->m_action = move(action);

        EventLoop::the().m_timer_list.append(timer.ptr());

        return timer;
    }

    Result<OwnedPtr<Timer>> Timer::create_repeating(unsigned int milliseconds, Action&& action)
    {
        auto timer = TRY(adopt_owned_if_nonnull(new (std::nothrow) Timer()));

        int status = timer_create(CLOCK_REALTIME, nullptr, &timer->m_timerid);
        if (status < 0) return err(errno);

        struct timespec time = { .tv_sec = milliseconds / 1000, .tv_nsec = (milliseconds % 1000) * 1'000'000 };
        struct itimerspec itimer = { .it_interval = { .tv_sec = 0, .tv_nsec = 0 }, .it_value = time };

        timer_settime(timer->m_timerid, 0, &itimer, nullptr);

        timer->m_repeating = true;
        timer->m_interval = time;
        timer->m_action = move(action);

        EventLoop::the().m_timer_list.append(timer.ptr());

        return timer;
    }

    void Timer::restart()
    {
        struct itimerspec itimer = { .it_interval = { .tv_sec = 0, .tv_nsec = 0 }, .it_value = m_interval };

        timer_settime(m_timerid, 0, &itimer, nullptr);

        readd_if_necessary();
    }

    void Timer::reset(unsigned int milliseconds)
    {
        m_interval = { .tv_sec = milliseconds / 1000, .tv_nsec = (milliseconds % 1000) * 1'000'000 };
        restart();
    }

    void Timer::stop()
    {
        EventLoop::the().m_timer_list.remove(this);
        m_stopped = true;

        struct itimerspec itimer;
        memset(&itimer, 0, sizeof(itimer));
        timer_settime(m_timerid, 0, &itimer, nullptr);
    }

    void Timer::check_if_should_invoke_action()
    {
        struct itimerspec remaining;
        if (timer_gettime(m_timerid, &remaining) < 0) return;

        if (!remaining.it_value.tv_sec && !remaining.it_value.tv_nsec && !m_stopped)
        {
            // Timer expired!
            m_action();

            if (!m_repeating)
            {
                EventLoop::the().m_timer_list.remove(this);
                m_stopped = true;
            }
            else
                restart();
        }
    }

    void Timer::readd_if_necessary()
    {
        if (m_stopped)
        {
            m_stopped = false;
            EventLoop::the().m_timer_list.append(this);
        }
    }

    Timer::~Timer()
    {
        if (m_timerid >= 0) timer_delete(m_timerid);
    }
}