merge master

37 files changed, 217 insertions, 102 deletions

diff --git a/src/crepe/CMakeLists.txt b/src/crepe/CMakeLists.txt
index 7e176e7..da9d492 100644
--- a/src/crepe/CMakeLists.txt
+++ b/src/crepe/CMakeLists.txt
@@ -1,13 +1,10 @@
 target_sources(crepe PUBLIC
 	Particle.cpp
-	ComponentManager.cpp
 	Component.cpp
 	Collider.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
-	ComponentManager.h
-	ComponentManager.hpp
 	Component.h
 	Collider.h
 	ValueBroker.h
@@ -16,6 +13,7 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 
 add_subdirectory(api)
 add_subdirectory(facade)
+add_subdirectory(manager)
 add_subdirectory(system)
 add_subdirectory(util)
 
diff --git a/src/crepe/api/BehaviorScript.cpp b/src/crepe/api/BehaviorScript.cpp
index 7bbace0..d22afdf 100644
--- a/src/crepe/api/BehaviorScript.cpp
+++ b/src/crepe/api/BehaviorScript.cpp
@@ -4,12 +4,12 @@
 
 using namespace crepe;
 
-BehaviorScript::BehaviorScript(game_object_id_t id, ComponentManager & mgr)
+BehaviorScript::BehaviorScript(game_object_id_t id, Mediator & mediator)
 	: Component(id),
-	  component_manager(mgr) {}
+	  mediator(mediator) {}
 
 template <>
 BehaviorScript & GameObject::add_component<BehaviorScript>() {
 	ComponentManager & mgr = this->component_manager;
-	return mgr.add_component<BehaviorScript>(this->id, mgr);
+	return mgr.add_component<BehaviorScript>(this->id, mgr.mediator);
 }
diff --git a/src/crepe/api/BehaviorScript.h b/src/crepe/api/BehaviorScript.h
index d556fe5..3909b96 100644
--- a/src/crepe/api/BehaviorScript.h
+++ b/src/crepe/api/BehaviorScript.h
@@ -23,14 +23,13 @@ class BehaviorScript : public Component {
 protected:
 	/**
 	 * \param id Parent \c GameObject id
-	 * \param component_manager Reference to component manager (passed through to \c Script
-	 * instance)
+	 * \param mediator Mediator reference
 	 *
 	 * \note Calls to this constructor (should) always pass through \c GameObject::add_component,
 	 * which has an exception for this specific component type. This was done so the user does
 	 * not have to pass references used within \c Script to each \c BehaviorScript instance.
 	 */
-	BehaviorScript(game_object_id_t id, ComponentManager & component_manager);
+	BehaviorScript(game_object_id_t id, Mediator & mediator);
 	//! Only ComponentManager is allowed to instantiate BehaviorScript
 	friend class ComponentManager;
 
@@ -55,8 +54,8 @@ protected:
 	friend class ScriptSystem;
 
 protected:
-	//! Reference to component manager (passed to Script)
-	ComponentManager & component_manager;
+	//! Reference mediator
+	Mediator & mediator;
 };
 
 /**
diff --git a/src/crepe/api/BehaviorScript.hpp b/src/crepe/api/BehaviorScript.hpp
index bd59337..b9bb1e2 100644
--- a/src/crepe/api/BehaviorScript.hpp
+++ b/src/crepe/api/BehaviorScript.hpp
@@ -13,14 +13,12 @@ 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(std::forward<Args>(args)...);
+	this->script = std::unique_ptr<Script>(new T(std::forward<Args>(args)...));
 
-	s->game_object_id = this->game_object_id;
-	s->active = this->active;
-	s->component_manager = this->component_manager;
-	s->event_manager = EventManager::get_instance();
+	this->script->game_object_id = this->game_object_id;
+	this->script->active = this->active;
+	this->script->mediator = this->mediator;
 
-	this->script = std::unique_ptr<Script>(s);
 	return *this;
 }
 
diff --git a/src/crepe/api/CMakeLists.txt b/src/crepe/api/CMakeLists.txt
index 25a9439..ac8f301 100644
--- a/src/crepe/api/CMakeLists.txt
+++ b/src/crepe/api/CMakeLists.txt
@@ -9,13 +9,10 @@ target_sources(crepe PUBLIC
 	Texture.cpp
 	AssetManager.cpp
 	Sprite.cpp
-	SaveManager.cpp
 	Config.cpp
 	Metadata.cpp
-	SceneManager.cpp
 	Camera.cpp
 	Animator.cpp
-	EventManager.cpp
 	IKeyListener.cpp
 	IMouseListener.cpp
 	LoopManager.cpp
@@ -43,15 +40,10 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	Texture.h 
 	AssetManager.h 
 	AssetManager.hpp
-	SaveManager.h
 	Scene.h
 	Metadata.h
-	SceneManager.h
-	SceneManager.hpp
 	Camera.h
 	Animator.h
-	EventManager.h
-	EventManager.hpp
 	EventHandler.h
 	EventHandler.hpp
 	Event.h
diff --git a/src/crepe/api/GameObject.hpp b/src/crepe/api/GameObject.hpp
index 17b17d7..a6b45b0 100644
--- a/src/crepe/api/GameObject.hpp
+++ b/src/crepe/api/GameObject.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "../ComponentManager.h"
+#include "../manager/ComponentManager.h"
 
 #include "GameObject.h"
 
diff --git a/src/crepe/api/IKeyListener.h b/src/crepe/api/IKeyListener.h
index 328a4c2..6ded107 100644
--- a/src/crepe/api/IKeyListener.h
+++ b/src/crepe/api/IKeyListener.h
@@ -1,8 +1,9 @@
 #pragma once
 
+#include "../manager/EventManager.h"
+
 #include "Event.h"
 #include "EventHandler.h"
-#include "EventManager.h"
 
 namespace crepe {
 
diff --git a/src/crepe/api/IMouseListener.h b/src/crepe/api/IMouseListener.h
index 15e1619..9e4fdf7 100644
--- a/src/crepe/api/IMouseListener.h
+++ b/src/crepe/api/IMouseListener.h
@@ -1,8 +1,9 @@
 #pragma once
 
+#include "../manager/EventManager.h"
+
 #include "Event.h"
 #include "EventHandler.h"
-#include "EventManager.h"
 
 namespace crepe {
 
diff --git a/src/crepe/api/LoopManager.cpp b/src/crepe/api/LoopManager.cpp
index b343250..dc2d9e0 100644
--- a/src/crepe/api/LoopManager.cpp
+++ b/src/crepe/api/LoopManager.cpp
@@ -1,5 +1,3 @@
-#include "../facade/SDLContext.h"
-
 #include "../system/AnimatorSystem.h"
 #include "../system/CollisionSystem.h"
 #include "../system/InputSystem.h"
@@ -9,12 +7,14 @@
 #include "../system/ScriptSystem.h"
 
 #include "LoopManager.h"
-#include "LoopTimer.h"
 
 using namespace crepe;
 using namespace std;
 
 LoopManager::LoopManager() {
+	this->mediator.component_manager = this->component_manager;
+	this->mediator.scene_manager = this->scene_manager;
+
 	this->load_system<AnimatorSystem>();
 	this->load_system<CollisionSystem>();
 	this->load_system<ParticleSystem>();
@@ -35,7 +35,7 @@ void LoopManager::set_running(bool running) { this->game_running = running; }
 void LoopManager::fixed_update() {}
 
 void LoopManager::loop() {
-	LoopTimer & timer = LoopTimer::get_instance();
+	LoopTimer & timer = this->loop_timer;
 	timer.start();
 
 	while (game_running) {
@@ -55,15 +55,17 @@ void LoopManager::loop() {
 }
 
 void LoopManager::setup() {
+	LoopTimer & timer = this->loop_timer;
+
 	this->game_running = true;
-	LoopTimer::get_instance().start();
-	LoopTimer::get_instance().set_fps(200);
+	timer.start();
+	timer.set_fps(200);
 }
 
 void LoopManager::render() {
-	if (this->game_running) {
-		this->get_system<RenderSystem>().update();
-	}
+	if (!this->game_running) return;
+
+	this->get_system<RenderSystem>().update();
 }
 
-void LoopManager::update() { LoopTimer & timer = LoopTimer::get_instance(); }
+void LoopManager::update() {}
diff --git a/src/crepe/api/LoopManager.h b/src/crepe/api/LoopManager.h
index 13e6dac..d8910a0 100644
--- a/src/crepe/api/LoopManager.h
+++ b/src/crepe/api/LoopManager.h
@@ -2,9 +2,12 @@
 
 #include <memory>
 
-#include "../ComponentManager.h"
+#include "../facade/SDLContext.h"
+#include "../manager/ComponentManager.h"
+#include "../manager/SceneManager.h"
 #include "../system/System.h"
-#include "api/SceneManager.h"
+
+#include "LoopTimer.h"
 
 namespace crepe {
 
@@ -85,10 +88,18 @@ private:
 	bool game_running = false;
 
 private:
+	//! Global context
+	Mediator mediator;
+
 	//! Component manager instance
-	ComponentManager component_manager{};
+	ComponentManager component_manager{mediator};
 	//! Scene manager instance
-	SceneManager scene_manager{component_manager};
+	SceneManager scene_manager{mediator};
+
+	//! SDL context \todo no more singletons!
+	SDLContext & sdl_context = SDLContext::get_instance();
+	//! Loop timer \todo no more singletons!
+	LoopTimer & loop_timer = LoopTimer::get_instance();
 
 private:
 	/**
diff --git a/src/crepe/api/LoopManager.hpp b/src/crepe/api/LoopManager.hpp
index 9cf470b..266758a 100644
--- a/src/crepe/api/LoopManager.hpp
+++ b/src/crepe/api/LoopManager.hpp
@@ -38,8 +38,11 @@ void LoopManager::load_system() {
 	static_assert(is_base_of<System, T>::value,
 				  "load_system must recieve a derivative class of System");
 
-	System * system = new T(this->component_manager);
-	this->systems[typeid(T)] = unique_ptr<System>(system);
+	const type_info & type = typeid(T);
+	if (this->systems.contains(type))
+		throw runtime_error(format("LoopManager: {} is already initialized", type.name()));
+	System * system = new T(this->mediator);
+	this->systems[type] = unique_ptr<System>(system);
 }
 
 } // namespace crepe
diff --git a/src/crepe/api/Scene.h b/src/crepe/api/Scene.h
index f6fdb2a..9f1e8ce 100644
--- a/src/crepe/api/Scene.h
+++ b/src/crepe/api/Scene.h
@@ -2,6 +2,7 @@
 
 #include <string>
 
+#include "../manager/Mediator.h"
 #include "../util/OptionalRef.h"
 
 namespace crepe {
@@ -34,6 +35,9 @@ public:
 	 */
 	virtual std::string get_name() const = 0;
 
+	// TODO: Late references should ALWAYS be private! This is currently kept as-is so unit tests
+	// keep passing, but this reference should not be directly accessible by the user!!!
+
 protected:
 	/**
 	 * \name Late references
@@ -46,8 +50,8 @@ protected:
 	 *
 	 * \{
 	 */
-	//! Reference to the ComponentManager
-	OptionalRef<ComponentManager> component_manager;
+	//! Mediator reference
+	OptionalRef<Mediator> mediator;
 	//! \}
 };
 
diff --git a/src/crepe/api/Script.cpp b/src/crepe/api/Script.cpp
index fcbe4c7..4091fd4 100644
--- a/src/crepe/api/Script.cpp
+++ b/src/crepe/api/Script.cpp
@@ -1,11 +1,17 @@
+#include <string>
+
+#include "../manager/SceneManager.h"
+
 #include "Script.h"
 
 using namespace crepe;
+using namespace std;
 
 Script::~Script() {
-	EventManager & evmgr = this->event_manager;
+	Mediator & mediator = this->mediator;
+	EventManager & mgr = mediator.event_manager;
 	for (auto id : this->listeners) {
-		evmgr.unsubscribe(id);
+		mgr.unsubscribe(id);
 	}
 }
 
@@ -13,3 +19,9 @@ template <>
 void Script::subscribe(const EventHandler<CollisionEvent> & callback) {
 	this->subscribe_internal(callback, this->game_object_id);
 }
+
+void Script::set_next_scene(const string & name) {
+	Mediator & mediator = this->mediator;
+	SceneManager & mgr = mediator.scene_manager;
+	mgr.set_next_scene(name);
+}
diff --git a/src/crepe/api/Script.h b/src/crepe/api/Script.h
index a0870cb..1b339b0 100644
--- a/src/crepe/api/Script.h
+++ b/src/crepe/api/Script.h
@@ -2,11 +2,11 @@
 
 #include <vector>
 
+#include "../manager/EventManager.h"
+#include "../manager/Mediator.h"
 #include "../types.h"
 #include "../util/OptionalRef.h"
 
-#include "EventManager.h"
-
 namespace crepe {
 
 class ScriptSystem;
@@ -106,6 +106,12 @@ protected:
 	template <typename EventType>
 	void subscribe(const EventHandler<EventType> & callback);
 
+	/**
+	 * \brief Set the next scene using SceneManager
+	 * \see SceneManager::set_next_scene
+	 */
+	void set_next_scene(const std::string & name);
+
 	//! \}
 
 private:
@@ -160,10 +166,8 @@ private:
 	game_object_id_t game_object_id;
 	//! Reference to parent component
 	OptionalRef<bool> active;
-	//! Reference to component manager instance
-	OptionalRef<ComponentManager> component_manager;
-	//! Reference to event manager instance
-	OptionalRef<EventManager> event_manager;
+	//! Mediator reference
+	OptionalRef<Mediator> mediator;
 	//! \}
 
 private:
diff --git a/src/crepe/api/Script.hpp b/src/crepe/api/Script.hpp
index a2463bf..45f1ff1 100644
--- a/src/crepe/api/Script.hpp
+++ b/src/crepe/api/Script.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "../ComponentManager.h"
+#include "../manager/ComponentManager.h"
 
 #include "BehaviorScript.h"
 #include "Script.h"
@@ -20,7 +20,8 @@ T & Script::get_component() const {
 
 template <typename T>
 RefVector<T> Script::get_components() const {
-	ComponentManager & mgr = this->component_manager;
+	Mediator & mediator = this->mediator;
+	ComponentManager & mgr = mediator.component_manager;
 
 	return mgr.get_components_by_id<T>(this->game_object_id);
 }
@@ -33,7 +34,8 @@ 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;
+	Mediator & mediator = this->mediator;
+	EventManager & mgr = mediator.event_manager;
 	subscription_t listener = mgr.subscribe<EventType>(
 		[this, callback](const EventType & data) -> bool {
 			bool & active = this->active;
diff --git a/src/crepe/manager/CMakeLists.txt b/src/crepe/manager/CMakeLists.txt
new file mode 100644
index 0000000..517b8a2
--- /dev/null
+++ b/src/crepe/manager/CMakeLists.txt
@@ -0,0 +1,20 @@
+target_sources(crepe PUBLIC
+	ComponentManager.cpp
+	EventManager.cpp
+	Manager.cpp
+	SaveManager.cpp
+	SceneManager.cpp
+)
+
+target_sources(crepe PUBLIC FILE_SET HEADERS FILES
+	ComponentManager.h
+	ComponentManager.hpp
+	EventManager.h
+	EventManager.hpp
+	Manager.h
+	Mediator.h
+	SaveManager.h
+	SceneManager.h
+	SceneManager.hpp
+)
+
diff --git a/src/crepe/ComponentManager.cpp b/src/crepe/manager/ComponentManager.cpp
index 5b73009..80cf8b4 100644
--- a/src/crepe/ComponentManager.cpp
+++ b/src/crepe/manager/ComponentManager.cpp
@@ -1,13 +1,16 @@
-#include "api/GameObject.h"
-#include "util/Log.h"
+#include "../api/GameObject.h"
+#include "../types.h"
+#include "../util/Log.h"
 
 #include "ComponentManager.h"
-#include "types.h"
 
 using namespace crepe;
 using namespace std;
 
-ComponentManager::ComponentManager() { dbg_trace(); }
+ComponentManager::ComponentManager(Mediator & mediator) : Manager(mediator) {
+	mediator.component_manager = *this;
+	dbg_trace();
+}
 ComponentManager::~ComponentManager() { dbg_trace(); }
 
 void ComponentManager::delete_all_components_of_id(game_object_id_t id) {
diff --git a/src/crepe/ComponentManager.h b/src/crepe/manager/ComponentManager.h
index 480124f..ad37586 100644
--- a/src/crepe/ComponentManager.h
+++ b/src/crepe/manager/ComponentManager.h
@@ -5,8 +5,10 @@
 #include <unordered_map>
 #include <vector>
 
-#include "Component.h"
-#include "types.h"
+#include "../Component.h"
+#include "../types.h"
+
+#include "Manager.h"
 
 namespace crepe {
 
@@ -17,7 +19,7 @@ class GameObject;
  * 
  * This class manages all components. It provides methods to add, delete and get components.
  */
-class ComponentManager {
+class ComponentManager : public Manager {
 	// TODO: This relation should be removed! I (loek) believe that the scene manager should
 	// create/destroy components because the GameObject's are stored in concrete Scene classes,
 	// which will in turn call GameObject's destructor, which will in turn call
@@ -26,7 +28,7 @@ class ComponentManager {
 	friend class SceneManager;
 
 public:
-	ComponentManager(); // dbg_trace
+	ComponentManager(Mediator & mediator);
 	~ComponentManager(); // dbg_trace
 
 	/**
diff --git a/src/crepe/ComponentManager.hpp b/src/crepe/manager/ComponentManager.hpp
index ffb38ec..ffb38ec 100644
--- a/src/crepe/ComponentManager.hpp
+++ b/src/crepe/manager/ComponentManager.hpp
diff --git a/src/crepe/api/EventManager.cpp b/src/crepe/manager/EventManager.cpp
index 20f0dd3..20f0dd3 100644
--- a/src/crepe/api/EventManager.cpp
+++ b/src/crepe/manager/EventManager.cpp
diff --git a/src/crepe/api/EventManager.h b/src/crepe/manager/EventManager.h
index 1a33023..d634f54 100644
--- a/src/crepe/api/EventManager.h
+++ b/src/crepe/manager/EventManager.h
@@ -5,8 +5,8 @@
 #include <unordered_map>
 #include <vector>
 
-#include "Event.h"
-#include "EventHandler.h"
+#include "../api/Event.h"
+#include "../api/EventHandler.h"
 
 namespace crepe {
 
diff --git a/src/crepe/api/EventManager.hpp b/src/crepe/manager/EventManager.hpp
index a5f4556..a5f4556 100644
--- a/src/crepe/api/EventManager.hpp
+++ b/src/crepe/manager/EventManager.hpp
diff --git a/src/crepe/manager/Manager.cpp b/src/crepe/manager/Manager.cpp
new file mode 100644
index 0000000..1182785
--- /dev/null
+++ b/src/crepe/manager/Manager.cpp
@@ -0,0 +1,5 @@
+#include "Manager.h"
+
+using namespace crepe;
+
+Manager::Manager(Mediator & mediator) : mediator(mediator) {}
diff --git a/src/crepe/manager/Manager.h b/src/crepe/manager/Manager.h
new file mode 100644
index 0000000..84d80fe
--- /dev/null
+++ b/src/crepe/manager/Manager.h
@@ -0,0 +1,24 @@
+#pragma once
+
+#include "Mediator.h"
+
+namespace crepe {
+
+/**
+ * \brief Base manager class
+ *
+ * Managers are used for various tasks that fall outside the ECS system category. All managers
+ * are required to register themselves to the mediator passed to the constructor, and this
+ * mutable reference is saved for convenience, even though not all managers use the mediator
+ * directly.
+ */
+class Manager {
+public:
+	Manager(Mediator & mediator);
+	virtual ~Manager() = default;
+
+protected:
+	Mediator & mediator;
+};
+
+} // namespace crepe
diff --git a/src/crepe/manager/Mediator.h b/src/crepe/manager/Mediator.h
new file mode 100644
index 0000000..71bd1c9
--- /dev/null
+++ b/src/crepe/manager/Mediator.h
@@ -0,0 +1,33 @@
+#pragma once
+
+#include "../util/OptionalRef.h"
+
+// TODO: remove these singletons:
+#include "EventManager.h"
+#include "SaveManager.h"
+
+namespace crepe {
+
+class ComponentManager;
+class SceneManager;
+
+/**
+ * Struct to pass references to classes that would otherwise need to be singletons down to
+ * other classes within the engine hierarchy. Made to prevent constant changes to subclasses to
+ * pass specific references through dependency injection. All references on this struct
+ * *should* be explicitly checked for availability as this struct does not guarantee anything.
+ *
+ * \note Dereferencing members of this struct should be deferred. If you are a user of this
+ * class, keep a reference to this mediator instead of just picking references from it when you
+ * receive an instance.
+ *
+ * \warning This class should never be directly accessible from the API
+ */
+struct Mediator {
+	OptionalRef<ComponentManager> component_manager;
+	OptionalRef<SceneManager> scene_manager;
+	OptionalRef<SaveManager> save_manager = SaveManager::get_instance();
+	OptionalRef<EventManager> event_manager = EventManager::get_instance();
+};
+
+} // namespace crepe
diff --git a/src/crepe/api/SaveManager.cpp b/src/crepe/manager/SaveManager.cpp
index c5f43ea..d4ed1c1 100644
--- a/src/crepe/api/SaveManager.cpp
+++ b/src/crepe/manager/SaveManager.cpp
@@ -1,9 +1,9 @@
+#include "../ValueBroker.h"
+#include "../api/Config.h"
 #include "../facade/DB.h"
 #include "../util/Log.h"
 
-#include "Config.h"
 #include "SaveManager.h"
-#include "ValueBroker.h"
 
 using namespace std;
 using namespace crepe;
diff --git a/src/crepe/api/SaveManager.h b/src/crepe/manager/SaveManager.h
index 3d8c852..3d8c852 100644
--- a/src/crepe/api/SaveManager.h
+++ b/src/crepe/manager/SaveManager.h
diff --git a/src/crepe/api/SceneManager.cpp b/src/crepe/manager/SceneManager.cpp
index 1f783ad..50a9fbb 100644
--- a/src/crepe/api/SceneManager.cpp
+++ b/src/crepe/manager/SceneManager.cpp
@@ -1,14 +1,15 @@
 #include <algorithm>
 #include <memory>
 
-#include "../ComponentManager.h"
-
+#include "ComponentManager.h"
 #include "SceneManager.h"
 
 using namespace crepe;
 using namespace std;
 
-SceneManager::SceneManager(ComponentManager & mgr) : component_manager(mgr) {}
+SceneManager::SceneManager(Mediator & mediator) : Manager(mediator) {
+	mediator.scene_manager = *this;
+}
 
 void SceneManager::set_next_scene(const string & name) { next_scene = name; }
 
@@ -26,7 +27,7 @@ void SceneManager::load_next_scene() {
 	unique_ptr<Scene> & scene = *it;
 
 	// Delete all components of the current scene
-	ComponentManager & mgr = this->component_manager;
+	ComponentManager & mgr = this->mediator.component_manager;
 	mgr.delete_all_components();
 
 	// Load the new scene
diff --git a/src/crepe/api/SceneManager.h b/src/crepe/manager/SceneManager.h
index f6f62cd..e0955c2 100644
--- a/src/crepe/api/SceneManager.h
+++ b/src/crepe/manager/SceneManager.h
@@ -3,7 +3,9 @@
 #include <memory>
 #include <vector>
 
-#include "Scene.h"
+#include "../api/Scene.h"
+
+#include "Manager.h"
 
 namespace crepe {
 
@@ -15,10 +17,9 @@ class ComponentManager;
  * This class manages scenes. It can add new scenes and load them. It also manages the current scene
  * and the next scene.
  */
-class SceneManager {
+class SceneManager : public Manager {
 public:
-	//! \param mgr  Reference to the ComponentManager
-	SceneManager(ComponentManager & mgr);
+	SceneManager(Mediator & mediator);
 
 public:
 	/**
@@ -44,8 +45,6 @@ private:
 	std::vector<std::unique_ptr<Scene>> scenes;
 	//! Next scene to load
 	std::string next_scene;
-	//! Reference to the ComponentManager
-	ComponentManager & component_manager;
 };
 
 } // namespace crepe
diff --git a/src/crepe/api/SceneManager.hpp b/src/crepe/manager/SceneManager.hpp
index 5c8e417..dff4e51 100644
--- a/src/crepe/api/SceneManager.hpp
+++ b/src/crepe/manager/SceneManager.hpp
@@ -12,7 +12,7 @@ void SceneManager::add_scene(Args &&... args) {
 	Scene * scene = new T(std::forward<Args>(args)...);
 	unique_ptr<Scene> unique_scene(scene);
 
-	unique_scene->component_manager = this->component_manager;
+	unique_scene->mediator = this->mediator;
 
 	this->scenes.emplace_back(std::move(unique_scene));
 
diff --git a/src/crepe/system/AnimatorSystem.cpp b/src/crepe/system/AnimatorSystem.cpp
index 4c40940..8bb6465 100644
--- a/src/crepe/system/AnimatorSystem.cpp
+++ b/src/crepe/system/AnimatorSystem.cpp
@@ -1,15 +1,15 @@
 #include <cstdint>
 
-#include "api/Animator.h"
-#include "facade/SDLContext.h"
+#include "../api/Animator.h"
+#include "../facade/SDLContext.h"
+#include "../manager/ComponentManager.h"
 
 #include "AnimatorSystem.h"
-#include "ComponentManager.h"
 
 using namespace crepe;
 
 void AnimatorSystem::update() {
-	ComponentManager & mgr = this->component_manager;
+	ComponentManager & mgr = this->mediator.component_manager;
 
 	RefVector<Animator> animations = mgr.get_components_by_type<Animator>();
 
diff --git a/src/crepe/system/ParticleSystem.cpp b/src/crepe/system/ParticleSystem.cpp
index 0e62a57..b14c52f 100644
--- a/src/crepe/system/ParticleSystem.cpp
+++ b/src/crepe/system/ParticleSystem.cpp
@@ -2,17 +2,17 @@
 #include <cstdlib>
 #include <ctime>
 
-#include "api/ParticleEmitter.h"
-#include "api/Transform.h"
+#include "../api/ParticleEmitter.h"
+#include "../api/Transform.h"
+#include "../manager/ComponentManager.h"
 
-#include "ComponentManager.h"
 #include "ParticleSystem.h"
 
 using namespace crepe;
 
 void ParticleSystem::update() {
 	// Get all emitters
-	ComponentManager & mgr = this->component_manager;
+	ComponentManager & mgr = this->mediator.component_manager;
 	RefVector<ParticleEmitter> emitters = mgr.get_components_by_type<ParticleEmitter>();
 
 	for (ParticleEmitter & emitter : emitters) {
diff --git a/src/crepe/system/PhysicsSystem.cpp b/src/crepe/system/PhysicsSystem.cpp
index 514a4b3..bebcf3d 100644
--- a/src/crepe/system/PhysicsSystem.cpp
+++ b/src/crepe/system/PhysicsSystem.cpp
@@ -1,17 +1,17 @@
 #include <cmath>
 
-#include "../ComponentManager.h"
 #include "../api/Config.h"
 #include "../api/Rigidbody.h"
 #include "../api/Transform.h"
 #include "../api/Vector2.h"
+#include "../manager/ComponentManager.h"
 
 #include "PhysicsSystem.h"
 
 using namespace crepe;
 
 void PhysicsSystem::update() {
-	ComponentManager & mgr = this->component_manager;
+	ComponentManager & mgr = this->mediator.component_manager;
 	RefVector<Rigidbody> rigidbodies = mgr.get_components_by_type<Rigidbody>();
 	RefVector<Transform> transforms = mgr.get_components_by_type<Transform>();
 
diff --git a/src/crepe/system/RenderSystem.cpp b/src/crepe/system/RenderSystem.cpp
index 11c9669..92dba43 100644
--- a/src/crepe/system/RenderSystem.cpp
+++ b/src/crepe/system/RenderSystem.cpp
@@ -5,12 +5,12 @@
 #include <stdexcept>
 #include <vector>
 
-#include "../ComponentManager.h"
 #include "../api/Camera.h"
 #include "../api/ParticleEmitter.h"
 #include "../api/Sprite.h"
 #include "../api/Transform.h"
 #include "../facade/SDLContext.h"
+#include "../manager/ComponentManager.h"
 
 #include "RenderSystem.h"
 
@@ -22,7 +22,7 @@ void RenderSystem::clear_screen() { this->context.clear_screen(); }
 void RenderSystem::present_screen() { this->context.present_screen(); }
 
 const Camera & RenderSystem::update_camera() {
-	ComponentManager & mgr = this->component_manager;
+	ComponentManager & mgr = this->mediator.component_manager;
 
 	RefVector<Camera> cameras = mgr.get_components_by_type<Camera>();
 
@@ -62,7 +62,7 @@ void RenderSystem::update() {
 bool RenderSystem::render_particle(const Sprite & sprite, const Camera & cam,
 								   const double & scale) {
 
-	ComponentManager & mgr = this->component_manager;
+	ComponentManager & mgr = this->mediator.component_manager;
 
 	vector<reference_wrapper<ParticleEmitter>> emitters
 		= mgr.get_components_by_id<ParticleEmitter>(sprite.game_object_id);
@@ -102,7 +102,7 @@ void RenderSystem::render_normal(const Sprite & sprite, const Camera & cam,
 }
 
 void RenderSystem::render() {
-	ComponentManager & mgr = this->component_manager;
+	ComponentManager & mgr = this->mediator.component_manager;
 	const Camera & cam = this->update_camera();
 
 	RefVector<Sprite> sprites = mgr.get_components_by_type<Sprite>();
diff --git a/src/crepe/system/ScriptSystem.cpp b/src/crepe/system/ScriptSystem.cpp
index 20a83f7..d6b2ca1 100644
--- a/src/crepe/system/ScriptSystem.cpp
+++ b/src/crepe/system/ScriptSystem.cpp
@@ -1,6 +1,6 @@
-#include "../ComponentManager.h"
 #include "../api/BehaviorScript.h"
 #include "../api/Script.h"
+#include "../manager/ComponentManager.h"
 
 #include "ScriptSystem.h"
 
@@ -10,7 +10,7 @@ using namespace crepe;
 void ScriptSystem::update() {
 	dbg_trace();
 
-	ComponentManager & mgr = this->component_manager;
+	ComponentManager & mgr = this->mediator.component_manager;
 	RefVector<BehaviorScript> behavior_scripts = mgr.get_components_by_type<BehaviorScript>();
 
 	for (BehaviorScript & behavior_script : behavior_scripts) {
diff --git a/src/crepe/system/System.cpp b/src/crepe/system/System.cpp
index 937a423..f68549b 100644
--- a/src/crepe/system/System.cpp
+++ b/src/crepe/system/System.cpp
@@ -4,4 +4,4 @@
 
 using namespace crepe;
 
-System::System(ComponentManager & mgr) : component_manager(mgr) { dbg_trace(); }
+System::System(const Mediator & mediator) : mediator(mediator) { dbg_trace(); }
diff --git a/src/crepe/system/System.h b/src/crepe/system/System.h
index 28ea20e..063dfbf 100644
--- a/src/crepe/system/System.h
+++ b/src/crepe/system/System.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include "../manager/Mediator.h"
+
 namespace crepe {
 
 class ComponentManager;
@@ -7,9 +9,8 @@ class ComponentManager;
 /**
  * \brief Base ECS system class
  *
- * This class is used as the base for all system classes. Classes derived from
- * System must implement the System::update() method and copy Script::Script
- * with the `using`-syntax.
+ * This class is used as the base for all system classes. Classes derived from System must
+ * implement the System::update() method and copy Script::Script with the `using`-syntax.
  */
 class System {
 public:
@@ -19,11 +20,11 @@ public:
 	virtual void update() = 0;
 
 public:
-	System(ComponentManager &);
+	System(const Mediator & m);
 	virtual ~System() = default;
 
 protected:
-	ComponentManager & component_manager;
+	const Mediator & mediator;
 };
 
 } // namespace crepe