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#ifndef TIMED_EVENTS_HPP
# define TIMED_EVENTS_HPP
#include <functional>
#include <chrono>
#include <list>
using namespace std::literals::chrono_literals;
namespace utils {
static constexpr std::chrono::milliseconds no_timeout = std::chrono::milliseconds(-1);
}
class TimedEventsManager;
/**
* A callback with an associated date.
*/
class TimedEvent
{
friend class TimedEventsManager;
public:
/**
* An event the occurs only once, at the given time_point
*/
explicit TimedEvent(std::chrono::steady_clock::time_point&& time_point,
std::function<void()> callback);
explicit TimedEvent(std::chrono::milliseconds&& duration,
std::function<void()> callback);
explicit TimedEvent(TimedEvent&&);
~TimedEvent();
/**
* Whether or not this event happens after the other one.
*/
bool is_after(const TimedEvent& other) const;
bool is_after(const std::chrono::steady_clock::time_point& time_point) const;
/**
* Return the duration difference between now and the event time point.
* If the difference would be negative (i.e. the event is expired), the
* returned value is 0 instead. The value cannot then be negative.
*/
std::chrono::milliseconds get_timeout() const;
void execute();
private:
/**
* The next time point at which the event is executed.
*/
std::chrono::steady_clock::time_point time_point;
/**
* The function to execute.
*/
const std::function<void()> callback;
/**
* Whether or not this events repeats itself until it is destroyed.
*/
const bool repeat;
/**
* This value is added to the time_point each time the event is executed,
* if repeat is true. Otherwise it is ignored.
*/
const std::chrono::milliseconds repeat_delay;
TimedEvent(const TimedEvent&) = delete;
TimedEvent& operator=(const TimedEvent&) = delete;
TimedEvent& operator=(TimedEvent&&) = delete;
};
/**
* A class managing a list of TimedEvents.
* They are sorted, new events can be added, removed, fetch, etc.
*/
class TimedEventsManager
{
public:
explicit TimedEventsManager();
~TimedEventsManager();
/**
* Add an event to the list of managed events. The list is sorted after
* this call.
*/
void add_event(TimedEvent&& event);
/**
* Returns the duration, in milliseconds, between now and the next
* available event. If the event is already expired (the duration is
* negative), 0 is returned instead (as in “it's not too late, execute it
* now”)
* Returns a negative value if no event is available.
*/
std::chrono::milliseconds get_timeout() const;
/**
* Execute all the expired events (if their expiration time is exactly
* now, or before now). The event is then removed from the list. If the
* event does repeat, its expiration time is updated and it is reinserted
* in the list at the correct position.
* Returns the number of executed events.
*/
std::size_t execute_expired_events();
private:
std::list<TimedEvent> events;
TimedEventsManager(const TimedEventsManager&) = delete;
TimedEventsManager(TimedEventsManager&&) = delete;
TimedEventsManager& operator=(const TimedEventsManager&) = delete;
TimedEventsManager& operator=(TimedEventsManager&&) = delete;
};
#endif // TIMED_EVENTS_HPP
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