class KeyChecker
{
public:
    KeyChecker(xcb_window_t window, xcb_keycode_t code, xcb_timestamp_t time, quint16 state)
        : m_window(window)
        , m_code(code)
        , m_time(time)
        , m_state(state)
        , m_error(false)
        , m_release(true)
    {
    }

    bool operator() (xcb_generic_event_t *ev)
    {
        if (m_error || !ev)
            return false;

        int type = ev->response_type & ~0x80;
        if (type != XCB_KEY_PRESS && type != XCB_KEY_RELEASE)
            return false;

        auto *event = reinterpret_cast<xcb_key_press_event_t *>(ev);

        if (event->event != m_window || event->detail != m_code || event->state != m_state) {
            m_error = true;
            return false;
        }

        if (type == XCB_KEY_PRESS) {
            m_error = !m_release || event->time - m_time > 10;
            return !m_error;
        }

        if (m_release) {
            m_error = true;
            return false;
        }

        m_release = true;
        m_time = event->time;

        return false;
    }

private:
    xcb_window_t m_window;
    xcb_keycode_t m_code;
    xcb_timestamp_t m_time;
    quint16 m_state;

    bool m_error;
    bool m_release;
};