From 9619f340827b00d4836406ded073a73b6df9386f Mon Sep 17 00:00:00 2001
From: Loek Le Blansch <loek@pipeframe.xyz>
Date: Thu, 21 Nov 2024 09:10:40 +0100
Subject: do not call event handlers when behaviorscript is not active + add
 doxygen

---
 src/crepe/api/BehaviorScript.hpp |  5 ++++-
 src/crepe/api/Event.h            |  6 ++++-
 src/crepe/api/EventManager.h     |  4 ++--
 src/crepe/api/Script.cpp         |  4 +++-
 src/crepe/api/Script.h           | 47 +++++++++++++++++++++++++++++++++++-----
 src/crepe/api/Script.hpp         |  8 +++++--
 6 files changed, 61 insertions(+), 13 deletions(-)

(limited to 'src/crepe/api')

diff --git a/src/crepe/api/BehaviorScript.hpp b/src/crepe/api/BehaviorScript.hpp
index dd197b3..5b5a418 100644
--- a/src/crepe/api/BehaviorScript.hpp
+++ b/src/crepe/api/BehaviorScript.hpp
@@ -14,9 +14,12 @@ BehaviorScript & BehaviorScript::set_script(Args &&... args) {
 	dbg_trace();
 	static_assert(std::is_base_of<Script, T>::value);
 	Script * s = new T(std::forward<Args>(args)...);
-	s->game_object_id = this->game_object_id;
+
+	s->game_object_id_ref = &this->game_object_id;
+	s->active_ref = &this->active;
 	s->component_manager_ref = &this->component_manager;
 	s->event_manager_ref = &EventManager::get_instance();
+
 	this->script = std::unique_ptr<Script>(s);
 	return *this;
 }
diff --git a/src/crepe/api/Event.h b/src/crepe/api/Event.h
index 9923a05..c1432e1 100644
--- a/src/crepe/api/Event.h
+++ b/src/crepe/api/Event.h
@@ -1,5 +1,5 @@
-// TODO discussing the location of these events
 #pragma once
+// TODO discussing the location of these events
 
 #include <string>
 
@@ -7,6 +7,8 @@
 
 #include "KeyCodes.h"
 
+namespace crepe {
+
 /**
  * \brief Base class for all event types in the system.
  */
@@ -113,3 +115,5 @@ public:
  * \brief Event triggered to indicate the application is shutting down.
  */
 class ShutDownEvent : public Event {};
+
+}
diff --git a/src/crepe/api/EventManager.h b/src/crepe/api/EventManager.h
index 348a04d..1a33023 100644
--- a/src/crepe/api/EventManager.h
+++ b/src/crepe/api/EventManager.h
@@ -77,7 +77,7 @@ public:
 	 * \param channel The channel to trigger the event on (default is CHANNEL_ALL, which triggers on all channels).
 	 */
 	template <typename EventType>
-	void trigger_event(const EventType & event, event_channel_t channel = CHANNEL_ALL);
+	void trigger_event(const EventType & event = {}, event_channel_t channel = CHANNEL_ALL);
 
 	/**
 	 * \brief Queue an event for later processing.
@@ -89,7 +89,7 @@ public:
 	 * \param channel The channel to associate with the event (default is CHANNEL_ALL).
 	 */
 	template <typename EventType>
-	void queue_event(const EventType & event, event_channel_t channel = CHANNEL_ALL);
+	void queue_event(const EventType & event = {}, event_channel_t channel = CHANNEL_ALL);
 
 	/**
 	 * \brief Process all queued events.
diff --git a/src/crepe/api/Script.cpp b/src/crepe/api/Script.cpp
index bac5ab2..d3fae07 100644
--- a/src/crepe/api/Script.cpp
+++ b/src/crepe/api/Script.cpp
@@ -11,5 +11,7 @@ Script::~Script() {
 
 template <>
 void Script::subscribe(const EventHandler<CollisionEvent> & callback) {
-	this->subscribe_internal(callback, this->game_object_id);
+	const game_object_id_t & game_object_id = *this->game_object_id_ref;
+	this->subscribe_internal(callback, game_object_id);
 }
+
diff --git a/src/crepe/api/Script.h b/src/crepe/api/Script.h
index 2d5e7a6..373b253 100644
--- a/src/crepe/api/Script.h
+++ b/src/crepe/api/Script.h
@@ -18,8 +18,10 @@ class ComponentManager;
  * This class is used as a base class for user-defined scripts that can be added to game
  * objects using the \c BehaviorScript component.
  *
- * \note Additional *events* (like Unity's OnDisable and OnEnable) should be implemented as
+ * \info Additional *events* (like Unity's OnDisable and OnEnable) should be implemented as
  * member or lambda methods in derivative user script classes and registered in \c init().
+ *
+ * \see feature_script
  */
 class Script {
 protected:
@@ -88,24 +90,40 @@ protected:
 	void logf(Args &&... args);
 
 	/**
-	 * \brief Subscribe to an event
-	 *
+	 * \brief Subscribe to an event with an explicit channel
 	 * \see EventManager::subscribe
 	 */
 	template <typename EventType>
 	void subscribe(const EventHandler<EventType> & callback, event_channel_t channel);
+	/**
+	 * \brief Subscribe to an event on EventManager::CHANNEL_ALL
+	 * \see EventManager::subscribe
+	 */
 	template <typename EventType>
 	void subscribe(const EventHandler<EventType> & callback);
 
 	//! \}
 
 private:
+	/**
+	 * \brief Internal subscribe function
+	 *
+	 * This function exists so certain template specializations of Script::subscribe can be
+	 * explicitly deleted, and does the following:
+	 * - Wrap the user-provided callback in a check that tests if the parent BehaviorScript
+	 *   component is still active
+	 * - Store the subscriber handle returned by the event manager so this listener is
+	 *   automatically unsubscribed at the end of this Script instance's life
+	 *
+	 * \tparam EventType concrete Event class
+	 * \param callback User-provided callback function
+	 * \param channel Event channel (may have been overridden by template specializations)
+	 */
 	template <typename EventType>
 	void subscribe_internal(const EventHandler<EventType> & callback, event_channel_t channel);
 
 protected:
-	// NOTE: Script must have a constructor without arguments so the game programmer doesn't need
-	// to manually add `using Script::Script` to their concrete script class.
+	// NOTE: This must be the only constructor on Script, see "Late references" below
 	Script() = default;
 	//! Only \c BehaviorScript instantiates Script
 	friend class BehaviorScript;
@@ -113,6 +131,7 @@ public:
 	// std::unique_ptr destroys script
 	virtual ~Script();
 
+private:
 	Script(const Script &) = delete;
 	Script(Script &&) = delete;
 	Script & operator=(const Script &) = delete;
@@ -125,10 +144,19 @@ private:
 	 * These references are set by BehaviorScript immediately after calling the constructor of
 	 * Script.
 	 *
+	 * \note Script must have a constructor without arguments so the game programmer doesn't need
+	 * to manually add `using Script::Script` to their concrete script class if they want to
+	 * implement a non-default constructor (e.g. for passing references to their own concrete
+	 * Script classes).
+	 *
+	 * \todo These should be converted to OptionalRef<> once `loek/util` is merged
+	 *
 	 * \{
 	 */
 	//! Game object ID of game object parent BehaviorScript is attached to
-	game_object_id_t game_object_id = -1;
+	const game_object_id_t * game_object_id_ref = nullptr;
+	//! Reference to parent component
+	bool * active_ref = nullptr;
 	//! Reference to component manager instance
 	ComponentManager * component_manager_ref = nullptr;
 	//! Reference to event manager instance
@@ -142,6 +170,13 @@ private:
 	std::vector<subscription_t> listeners;
 };
 
+/**
+ * \brief Subscribe to CollisionEvent for the current GameObject
+ *
+ * This is a template specialization for Script::subscribe which automatically sets the event
+ * channel so the callback handler is only called for CollisionEvent events that apply to the
+ * current GameObject the parent BehaviorScript is attached to.
+ */
 template <>
 void Script::subscribe(const EventHandler<CollisionEvent> & callback);
 template <>
diff --git a/src/crepe/api/Script.hpp b/src/crepe/api/Script.hpp
index 96e4a36..8186bd4 100644
--- a/src/crepe/api/Script.hpp
+++ b/src/crepe/api/Script.hpp
@@ -22,7 +22,7 @@ template <typename T>
 std::vector<std::reference_wrapper<T>> Script::get_components() const {
 	ComponentManager & mgr = *this->component_manager_ref;
 
-	return mgr.get_components_by_id<T>(this->game_object_id);
+	return mgr.get_components_by_id<T>(*this->game_object_id_ref);
 }
 
 template <typename... Args>
@@ -33,7 +33,11 @@ void Script::logf(Args &&... args) {
 template <typename EventType>
 void Script::subscribe_internal(const EventHandler<EventType> & callback, event_channel_t channel) {
 	EventManager & mgr = *this->event_manager_ref;
-	subscription_t listener = mgr.subscribe<EventType>(callback, channel);
+	subscription_t listener = mgr.subscribe<EventType>([this, callback](const EventType & data) -> bool {
+		bool & active = *this->active_ref;
+		if (!active) return false;
+		return callback(data);
+	}, channel);
 	this->listeners.push_back(listener);
 }
 
-- 
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