From 502fb8e8d1dcfe10f55fdef2cdfb71afec806204 Mon Sep 17 00:00:00 2001
From: Loek Le Blansch <loek@pipeframe.xyz>
Date: Thu, 21 Nov 2024 09:43:13 +0100
Subject: pull script/event changes from `loek/collision-system`

---
 src/crepe/api/BehaviorScript.h   |  7 +++--
 src/crepe/api/BehaviorScript.hpp | 11 +++++---
 src/crepe/api/Event.h            | 12 ++++----
 src/crepe/api/EventManager.h     |  4 +--
 src/crepe/api/Script.cpp         |  6 ++++
 src/crepe/api/Script.h           | 60 +++++++++++++++++++++++++++++++++++-----
 src/crepe/api/Script.hpp         | 20 ++++++++++++--
 7 files changed, 96 insertions(+), 24 deletions(-)

(limited to 'src/crepe')

diff --git a/src/crepe/api/BehaviorScript.h b/src/crepe/api/BehaviorScript.h
index 9d85d4c..d556fe5 100644
--- a/src/crepe/api/BehaviorScript.h
+++ b/src/crepe/api/BehaviorScript.h
@@ -39,11 +39,14 @@ public:
 	 * \brief Set the concrete script of this component
 	 *
 	 * \tparam T Concrete script type (derived from \c crepe::Script)
+	 * \tparam Args Arguments for concrete script constructor
+	 *
+	 * \param args Arguments for concrete script constructor (forwarded using perfect forwarding)
 	 *
 	 * \returns Reference to BehaviorScript component (`*this`)
 	 */
-	template <class T>
-	BehaviorScript & set_script();
+	template <class T, typename... Args>
+	BehaviorScript & set_script(Args &&... args);
 
 protected:
 	//! Script instance
diff --git a/src/crepe/api/BehaviorScript.hpp b/src/crepe/api/BehaviorScript.hpp
index dd1efd5..5b5a418 100644
--- a/src/crepe/api/BehaviorScript.hpp
+++ b/src/crepe/api/BehaviorScript.hpp
@@ -9,14 +9,17 @@
 
 namespace crepe {
 
-template <class T>
-BehaviorScript & BehaviorScript::set_script() {
+template <class T, typename... Args>
+BehaviorScript & BehaviorScript::set_script(Args &&... args) {
 	dbg_trace();
 	static_assert(std::is_base_of<Script, T>::value);
-	Script * s = new T();
-	s->game_object_id = this->game_object_id;
+	Script * s = new T(std::forward<Args>(args)...);
+
+	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 06cf7f3..ab4be2b 100644
--- a/src/crepe/api/Event.h
+++ b/src/crepe/api/Event.h
@@ -1,10 +1,12 @@
-// TODO discussing the location of these events
 #pragma once
+// TODO discussing the location of these events
 
 #include <string>
 
 #include "KeyCodes.h"
 
+namespace crepe {
+
 /**
  * \brief Base class for all event types in the system.
  */
@@ -91,11 +93,7 @@ public:
 /**
  * \brief Event triggered during a collision between objects.
  */
-class CollisionEvent : public Event {
-public:
-	//! Data describing the collision (currently not implemented).
-	// Collision collisionData;
-};
+class CollisionEvent : public Event { };
 
 /**
  * \brief Event triggered when text is submitted, e.g., from a text input.
@@ -110,3 +108,5 @@ 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 9ebb074..d3fae07 100644
--- a/src/crepe/api/Script.cpp
+++ b/src/crepe/api/Script.cpp
@@ -9,3 +9,9 @@ Script::~Script() {
 	}
 }
 
+template <>
+void Script::subscribe(const EventHandler<CollisionEvent> & callback) {
+	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 c9eb211..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:
@@ -88,18 +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, event_channel_t channel = EventManager::CHANNEL_ALL);
+	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;
@@ -107,6 +131,7 @@ public:
 	// std::unique_ptr destroys script
 	virtual ~Script();
 
+private:
 	Script(const Script &) = delete;
 	Script(Script &&) = delete;
 	Script & operator=(const Script &) = delete;
@@ -119,10 +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
@@ -136,6 +170,18 @@ 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 <>
+void Script::subscribe(const EventHandler<CollisionEvent> & callback, event_channel_t) = delete;
+
 } // namespace crepe
 
 #include "Script.hpp"
diff --git a/src/crepe/api/Script.hpp b/src/crepe/api/Script.hpp
index 42c8f0b..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>
@@ -31,10 +31,24 @@ void Script::logf(Args &&... args) {
 }
 
 template <typename EventType>
-void Script::subscribe(const EventHandler<EventType> & callback, event_channel_t channel) {
+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);
 }
 
+template <typename EventType>
+void Script::subscribe(const EventHandler<EventType> & callback, event_channel_t channel) {
+	this->subscribe_internal(callback, channel);
+}
+
+template <typename EventType>
+void Script::subscribe(const EventHandler<EventType> & callback) {
+	this->subscribe_internal(callback, EventManager::CHANNEL_ALL);
+}
+
 } // namespace crepe
-- 
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