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#pragma once
#include <memory>
#include <unordered_map>
#include <vector>
#include <functional>
#include <typeindex>
#include <type_traits>
#include "Event.h"
#include "EventHandler.h"
/**
* \class EventManager
* \brief The EventManager class is responsible for managing the subscription, triggering,
* and queueing of events. It handles events and dispatches them to appropriate subscribers.
*/
class EventManager {
public:
/**
* \brief Deleted copy constructor to prevent copying of the EventManager instance.
*/
EventManager(const EventManager &) = delete;
/**
* \brief Deleted copy assignment operator to prevent assignment of the EventManager instance.
*/
const EventManager & operator=(const EventManager &) = delete;
/**
* \brief Get the singleton instance of the EventManager.
*
* This method returns the unique instance of the EventManager, creating it on the first call.
*
* \return Reference to the EventManager instance.
*/
static EventManager & get_instance() {
static EventManager instance;
return instance;
}
/**
* \brief Subscribe to an event.
*
* This method allows the registration of a callback for a specific event type and channel.
*
* \tparam EventType The type of the event to subscribe to.
* \param callback The callback function to invoke when the event is triggered.
* \param channel The channel number to subscribe to (default is 0).
*/
template <typename EventType>
void subscribe(EventHandler<EventType> && callback, int channel = 0);
/**
* \brief Unsubscribe from an event.
*
* This method removes a previously registered callback from an event.
*
* \tparam EventType The type of the event to unsubscribe from.
* \param callback The callback function to remove from the subscription list.
* \param channel The event ID to unsubscribe from.
*/
template <typename EventType>
void unsubscribe(const EventHandler<EventType> &, int channel);
/**
* \brief Trigger an event.
*
* This method invokes the appropriate callback(s) for the specified event.
*
* \tparam EventType The type of the event to trigger.
* \param event The event data to pass to the callback.
* \param channel The channel from which to trigger the event (default is 0).
*/
template <typename EventType>
void trigger_event(const EventType & event, int channel);
/**
* \brief Queue an event for later processing.
*
* This method adds an event to the event queue, which will be processed in the
* dispatch_events function.
*
* \tparam EventType The type of the event to queue.
* \param event The event to queue.
* \param channel The channel number for the event (default is 0).
*/
template <typename EventType>
void queue_event(EventType&& event, int channel);
/**
* \brief Dispatch all queued events.
*
* This method processes all events in the event queue and triggers the corresponding
* callbacks for each event.
*/
void dispatch_events();
private:
/**
* \brief Default constructor for the EventManager.
*
* This constructor is private to enforce the singleton pattern.
*/
EventManager() = default;
//! The queue of events to be processed.
std::vector<std::tuple<std::unique_ptr<Event>, int, std::type_index>> events_queue;
//! Registered event handlers.
std::unordered_map<std::type_index, std::vector<std::unique_ptr<IEventHandlerWrapper>>> subscribers;
//! Event handlers indexed by event ID.
std::unordered_map<std::type_index, std::unordered_map<int, std::vector<std::unique_ptr<IEventHandlerWrapper>>>> subscribers_by_event_id;
};
template <typename EventType>
void EventManager::subscribe(EventHandler<EventType> && callback, int channel) {
std::type_index event_type = typeid(EventType);
std::unique_ptr<EventHandlerWrapper<EventType>> handler = std::make_unique<EventHandlerWrapper<EventType>>(callback);
if (channel) {
std::unordered_map<int, std::vector<std::unique_ptr<IEventHandlerWrapper>>>& handlers_map = this->subscribers_by_event_id[event_type];
std::unordered_map<int, std::vector<std::unique_ptr<IEventHandlerWrapper>>>::iterator handlers = handlers_map.find(channel);
if (handlers != handlers_map.end()) {
handlers->second.emplace_back(std::move(handler));
} else {
handlers_map[channel].emplace_back(std::move(handler));
}
} else {
std::vector<std::unique_ptr<IEventHandlerWrapper>>& handlers = this->subscribers[event_type];
handlers.emplace_back(std::move(handler));
}
}
template <typename EventType>
void EventManager::queue_event(EventType&& event, int channel) {
std::type_index event_type = std::type_index(typeid(EventType));
std::unique_ptr<EventType> event_ptr = std::make_unique<EventType>(std::forward<EventType>(event));
std::tuple<std::unique_ptr<Event>, int, std::type_index> tuple(
std::move(event_ptr),
channel,
event_type
);
this->events_queue.push_back(std::move(tuple));
}
template <typename EventType>
void EventManager::trigger_event(const EventType & event, int channel) {
std::type_index event_type = std::type_index(typeid(EventType));
if (channel > 0) {
std::unordered_map<int, std::vector<std::unique_ptr<IEventHandlerWrapper>>>& handlers_map = subscribers_by_event_id[event_type];
std::unordered_map<int, std::vector<std::unique_ptr<IEventHandlerWrapper>>>::iterator handlers_it = handlers_map.find(channel);
if (handlers_it != handlers_map.end()) {
std::vector<std::unique_ptr<IEventHandlerWrapper>>& handlers = handlers_it->second;
for (std::vector<std::unique_ptr<IEventHandlerWrapper>>::iterator it = handlers.begin(); it != handlers.end();) {
// erases callback if callback function returns true
if ((*it)->exec(event)) {
it = handlers.erase(it);
} else {
++it;
}
}
}
} else {
std::vector<std::unique_ptr<IEventHandlerWrapper>>& handlers = subscribers[event_type];
for (std::vector<std::unique_ptr<IEventHandlerWrapper>>::iterator it = handlers.begin(); it != handlers.end();) {
// erases callback if callback function returns true
if ((*it)->exec(event)) {
it = handlers.erase(it);
} else {
++it;
}
}
}
}
template <typename EventType>
void EventManager::unsubscribe(const EventHandler<EventType> & callback, int channel) {
std::type_index event_type(typeid(EventType));
std::string handler_name = callback.target_type().name();
if (channel) {
std::unordered_map<std::type_index, std::unordered_map<int, std::vector<std::unique_ptr<IEventHandlerWrapper>>>>::iterator subscriber_list = this->subscribers_by_event_id.find(event_type);
if (subscriber_list != this->subscribers_by_event_id.end()) {
std::unordered_map<int, std::vector<std::unique_ptr<IEventHandlerWrapper>>>& handlers_map = subscriber_list->second;
std::unordered_map<int, std::vector<std::unique_ptr<IEventHandlerWrapper>>>::iterator handlers = handlers_map.find(channel);
if (handlers != handlers_map.end()) {
std::vector<std::unique_ptr<IEventHandlerWrapper>>& callbacks = handlers->second;
for (std::vector<std::unique_ptr<IEventHandlerWrapper>>::iterator it = callbacks.begin(); it != callbacks.end(); ++it) {
if ((*it)->get_type() == handler_name) {
it = callbacks.erase(it);
return;
}
}
}
}
} else {
std::unordered_map<std::type_index, std::vector<std::unique_ptr<IEventHandlerWrapper>>>::iterator handlers_it = this->subscribers.find(event_type);
if (handlers_it != this->subscribers.end()) {
std::vector<std::unique_ptr<IEventHandlerWrapper>>& handlers = handlers_it->second;
for (std::vector<std::unique_ptr<IEventHandlerWrapper>>::iterator it = handlers.begin(); it != handlers.end(); ++it) {
if ((*it)->get_type() == handler_name) {
it = handlers.erase(it);
return;
}
}
}
}
}
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