From d0c5ef1a1d1a041e1e18ac3d0977acf1bc6896f5 Mon Sep 17 00:00:00 2001
From: WiggleWizard <1405402+WiggleWizard@users.noreply.github.com>
Date: Thu, 19 Sep 2024 17:52:01 +0100
Subject: [PATCH] Initial infrastructure for C# scene callbacks in subsystems

---
 Nuake/Engine.cpp                              | 33 +++++++
 Nuake/Engine.h                                |  4 +
 Nuake/src/Core/MulticastDelegate.h            | 86 +++++++++++++++++++
 Nuake/src/Scene/Scene.cpp                     |  4 +
 Nuake/src/Scene/Scene.h                       | 10 +++
 Nuake/src/Scene/Systems/ScriptingSystem.cpp   |  4 +
 Nuake/src/Scene/Systems/ScriptingSystem.h     |  1 +
 Nuake/src/Scene/Systems/System.h              |  9 ++
 Nuake/src/Subsystems/EngineSubsystem.h        |  7 ++
 .../Subsystems/EngineSubsystemScriptable.cpp  | 12 +++
 .../Subsystems/EngineSubsystemScriptable.h    |  3 +
 Nuake/src/Window.cpp                          |  7 +-
 Nuake/src/Window.h                            | 11 ++-
 NuakeNet/src/EngineSubsystem.cs               |  3 +
 14 files changed, 190 insertions(+), 4 deletions(-)
 create mode 100644 Nuake/src/Core/MulticastDelegate.h

diff --git a/Nuake/Engine.cpp b/Nuake/Engine.cpp
index 52e4b895..20deae85 100644
--- a/Nuake/Engine.cpp
+++ b/Nuake/Engine.cpp
@@ -40,6 +40,8 @@ namespace Nuake
 
 	void Engine::Init()
 	{
+		Window::Get()->OnWindowSetScene().AddStatic(&Engine::OnWindowSetScene);
+		
 		ScriptingEngineNet::Get().AddListener<ScriptingEngineNet::GameAssemblyLoadedDelegate>(&Engine::OnScriptingEngineGameAssemblyLoaded);
 		
 		AudioManager::Get().Initialize();
@@ -257,6 +259,15 @@ namespace Nuake
 		return std::reinterpret_pointer_cast<EngineSubsystemScriptable>(subsystems[subsystemId]);
 	}
 
+	void Engine::OnWindowSetScene(Ref<Scene> scene)
+	{
+		if (scene != nullptr)
+		{
+			scene->OnPreInitialize().AddStatic(&Engine::OnScenePreInitialize, scene);
+			scene->OnPostInitialize().AddStatic(&Engine::OnScenePostInitialize, scene);
+		}
+	}
+
 	void Engine::InitializeCoreSubsystems()
 	{
 	}
@@ -296,6 +307,28 @@ namespace Nuake
 		}
 	}
 
+	void Engine::OnScenePreInitialize(Ref<Scene> scene)
+	{
+		for (auto subsystem : subsystems)
+		{
+			if (subsystem == nullptr)
+				continue;
+
+			subsystem->OnScenePreInitialize(scene);
+		}
+	}
+
+	void Engine::OnScenePostInitialize(Ref<Scene> scene)
+	{
+		for (auto subsystem : subsystems)
+		{
+			if (subsystem == nullptr)
+				continue;
+
+			subsystem->OnScenePostInitialize(scene);
+		}
+	}
+
 	bool Engine::LoadProject(Ref<Project> project)
 	{
 		currentProject = project;
diff --git a/Nuake/Engine.h b/Nuake/Engine.h
index d20ca984..00bc623e 100644
--- a/Nuake/Engine.h
+++ b/Nuake/Engine.h
@@ -58,9 +58,13 @@ namespace Nuake
 		static Ref<EngineSubsystemScriptable> GetScriptedSubsystem(const int subsystemId);
 
 	protected:
+		static void OnWindowSetScene(Ref<Scene> scene);
 		static void InitializeCoreSubsystems();
 		static void OnScriptingEngineGameAssemblyLoaded();
 
+		static void OnScenePreInitialize(Ref<Scene> scene);
+		static void OnScenePostInitialize(Ref<Scene> scene);
+
 	private:
 		static Ref<Window> currentWindow;
 		static Ref<Project> currentProject;
diff --git a/Nuake/src/Core/MulticastDelegate.h b/Nuake/src/Core/MulticastDelegate.h
new file mode 100644
index 00000000..fb2a3160
--- /dev/null
+++ b/Nuake/src/Core/MulticastDelegate.h
@@ -0,0 +1,86 @@
+#pragma once
+
+#include <functional>
+#include <vector>
+#include <algorithm>
+
+#define DECLARE_MULTICAST_DELEGATE(multicastDelegateName, ...) typedef MulticastDelegate<__VA_ARGS__> multicastDelegateName; 
+
+template<typename... Args>
+class MulticastDelegate
+{
+public:
+    using DelegateID = size_t;
+
+    // Add a callable with bound variables (supports no arguments as well)
+    template<typename Callable, typename... BoundArgs>
+    DelegateID AddStatic(Callable&& func, BoundArgs&&... boundArgs)
+    {
+        DelegateID id = nextID++;
+        auto boundFunction = [=](Args... args) {
+            if constexpr (sizeof...(Args) > 0)
+            {
+                func(boundArgs..., std::forward<Args>(args)...);
+            }
+            else
+            {
+                func(boundArgs...);
+            }
+        };
+        delegates.push_back({id, boundFunction});
+        return id;
+    }
+    
+    template<typename Callable, typename Obj, typename... BoundArgs>
+    DelegateID AddObject(Callable&& func, Obj* object, BoundArgs&&... boundArgs)
+    {
+        DelegateID id = nextID++;
+        auto boundFunction = [=](Args... args) {
+            if constexpr (sizeof...(Args) > 0)
+            {
+                (object->*func)(boundArgs..., std::forward<Args>(args)...);
+            }
+            else
+            {
+                (object->*func)(boundArgs...);
+            }
+        };
+        delegates.push_back({id, boundFunction});
+        return id;
+    }
+
+    // Remove a callable using the token returned by Add()
+    void Remove(DelegateID id)
+    {
+        auto it = std::remove_if(delegates.begin(), delegates.end(), [id](const auto& pair)
+        {
+            return pair.first == id;
+        });
+        
+        if (it != delegates.end())
+        {
+            delegates.erase(it, delegates.end());
+        }
+    }
+
+    // Clear all delegates
+    void Clear()
+    {
+        delegates.clear();
+    }
+
+    // Invoke all callables
+    void Broadcast(Args... args)
+    {
+        for (auto& [id, delegate] : delegates)
+        {
+            delegate(std::forward<Args>(args)...);
+        }
+    }
+
+private:
+    using DelegatePair = std::pair<DelegateID, std::function<void(Args...)>>;
+    
+    std::vector<DelegatePair> delegates;  // Vector of (ID, callable) pairs
+    DelegateID nextID = 0;  // Unique ID generator
+};
diff --git a/Nuake/src/Scene/Scene.cpp b/Nuake/src/Scene/Scene.cpp
index 09cc2154..4cdb06da 100644
--- a/Nuake/src/Scene/Scene.cpp
+++ b/Nuake/src/Scene/Scene.cpp
@@ -243,6 +243,8 @@ namespace Nuake
 
 	bool Scene::OnInit()
 	{
+		preInitializeDelegate.Broadcast();
+		
 		for (auto& system : m_Systems)
 		{
 			if (!system->Init())
@@ -250,6 +252,8 @@ namespace Nuake
 				return false;
 			}
 		}
+		
+		postInitializeDelegate.Broadcast();
 
 		return true;
 	}
diff --git a/Nuake/src/Scene/Scene.h b/Nuake/src/Scene/Scene.h
index aa3e6ff7..fadf220a 100644
--- a/Nuake/src/Scene/Scene.h
+++ b/Nuake/src/Scene/Scene.h
@@ -19,6 +19,9 @@ namespace Nuake
 	class Entity;
 	class SceneRenderer;
 
+	DECLARE_MULTICAST_DELEGATE(PreInitializeDelegate)
+	DECLARE_MULTICAST_DELEGATE(PostInitializeDelegate)
+
 	class Scene : public ISerializable
 	{
 		friend Entity;
@@ -92,6 +95,13 @@ namespace Nuake
 		// Component specific utilies
 		void CreateSkeleton(Entity& entity);
 
+		PreInitializeDelegate& OnPreInitialize() { return preInitializeDelegate; }
+		PostInitializeDelegate& OnPostInitialize() { return postInitializeDelegate; }
+
+	protected:
+		PreInitializeDelegate preInitializeDelegate;
+		PostInitializeDelegate postInitializeDelegate;
+		
 	private:
 		void CreateSkeletonTraverse(Entity& entity, SkeletonNode& skeletonNode);
 	};
diff --git a/Nuake/src/Scene/Systems/ScriptingSystem.cpp b/Nuake/src/Scene/Systems/ScriptingSystem.cpp
index 6aaaae8c..9c094ea2 100644
--- a/Nuake/src/Scene/Systems/ScriptingSystem.cpp
+++ b/Nuake/src/Scene/Systems/ScriptingSystem.cpp
@@ -18,6 +18,8 @@ namespace Nuake
 	{
 		Logger::Log("Initializing ScriptingSystem");
 
+		preInitDelegate.Broadcast();
+
 		auto& scriptingEngineNet = ScriptingEngineNet::Get();
 		scriptingEngineNet.Uninitialize();
 		scriptingEngineNet.Initialize();
@@ -70,6 +72,8 @@ namespace Nuake
 			}
 		}
 
+		postInitDelegate.Broadcast();
+
 		return true;
 	}
 
diff --git a/Nuake/src/Scene/Systems/ScriptingSystem.h b/Nuake/src/Scene/Systems/ScriptingSystem.h
index 106e7ba8..20f46794 100644
--- a/Nuake/src/Scene/Systems/ScriptingSystem.h
+++ b/Nuake/src/Scene/Systems/ScriptingSystem.h
@@ -1,5 +1,6 @@
 #pragma once
 #include "System.h"
+#include "src/Core/MulticastDelegate.h"
 
 namespace Nuake {
 	class Scene;
diff --git a/Nuake/src/Scene/Systems/System.h b/Nuake/src/Scene/Systems/System.h
index 382fa84d..fa954e7a 100644
--- a/Nuake/src/Scene/Systems/System.h
+++ b/Nuake/src/Scene/Systems/System.h
@@ -1,6 +1,8 @@
 #pragma once
+
 #include "src/Core/Timestep.h"
 #include "src/Core/Core.h"
+#include "src/Core/MulticastDelegate.h"
 
 namespace Nuake
 {
@@ -17,5 +19,12 @@ namespace Nuake
 		virtual void FixedUpdate(Timestep ts) = 0;
 		virtual void EditorUpdate() {}
 		virtual void Exit() = 0;
+
+		MulticastDelegate<>& OnPreInit() { return preInitDelegate; }
+		MulticastDelegate<>& OnPostInit() { return postInitDelegate; }
+
+	protected:
+		MulticastDelegate<> preInitDelegate;
+		MulticastDelegate<> postInitDelegate;
 	};
 }
diff --git a/Nuake/src/Subsystems/EngineSubsystem.h b/Nuake/src/Subsystems/EngineSubsystem.h
index f1c25b30..3fcc93b5 100644
--- a/Nuake/src/Subsystems/EngineSubsystem.h
+++ b/Nuake/src/Subsystems/EngineSubsystem.h
@@ -1,11 +1,15 @@
 #pragma once
 
+#include "src/Core/Core.h"
+
 /**
  * Specific type of subsystem that runs within the context of the engine, being created at the start of the
  * engine's lifetime and destroyed just before the engine shuts down.
  */
 namespace Nuake
 {
+    class Scene;
+
     class EngineSubsystem
     {
     public:
@@ -15,6 +19,9 @@ namespace Nuake
         virtual void Initialize() {}
         virtual void Tick(float deltaTime) {}
 
+        virtual void OnScenePreInitialize(Ref<Scene> scene) {}
+        virtual void OnScenePostInitialize(Ref<Scene> scene) {}
+
     private:
         bool canEverTick = false;
     };
diff --git a/Nuake/src/Subsystems/EngineSubsystemScriptable.cpp b/Nuake/src/Subsystems/EngineSubsystemScriptable.cpp
index 4076ae5f..c5d8a17d 100644
--- a/Nuake/src/Subsystems/EngineSubsystemScriptable.cpp
+++ b/Nuake/src/Subsystems/EngineSubsystemScriptable.cpp
@@ -29,6 +29,18 @@ void EngineSubsystemScriptable::Tick(float deltaTime)
 
     cSharpObjectInstance.InvokeMethod("OnTick", deltaTime);
 }
+
+void EngineSubsystemScriptable::OnScenePreInitialize(Ref<Scene> scene)
+{
+}
+
+void EngineSubsystemScriptable::OnScenePostInitialize(Ref<Scene> scene)
+{
+    if (!cSharpObjectInstance.IsValid())
+        return;
+
+    cSharpObjectInstance.InvokeMethod("OnScenePostInitialize", scene);
+}
     
 }
 
diff --git a/Nuake/src/Subsystems/EngineSubsystemScriptable.h b/Nuake/src/Subsystems/EngineSubsystemScriptable.h
index 69acae01..14823401 100644
--- a/Nuake/src/Subsystems/EngineSubsystemScriptable.h
+++ b/Nuake/src/Subsystems/EngineSubsystemScriptable.h
@@ -19,6 +19,9 @@ namespace Nuake
         virtual void Initialize() override;
         virtual void Tick(float deltaTime) override;
 
+        virtual void OnScenePreInitialize(Ref<Scene> scene) override;
+        virtual void OnScenePostInitialize(Ref<Scene> scene) override;
+
     private:
         Coral::ManagedObject cSharpObjectInstance;
     };
diff --git a/Nuake/src/Window.cpp b/Nuake/src/Window.cpp
index 18508d7a..fc03b7ff 100644
--- a/Nuake/src/Window.cpp
+++ b/Nuake/src/Window.cpp
@@ -303,9 +303,12 @@ Ref<Scene> Window::GetScene()
     return this->scene;
 }
 
-bool Window::SetScene(Ref<Scene> scene)
+bool Window::SetScene(Ref<Scene> newScene)
 {
-    this->scene = scene;
+    scene = newScene;
+
+    windowSetSceneDelegate.Broadcast(newScene);
+    
     return true;
 }
 
diff --git a/Nuake/src/Window.h b/Nuake/src/Window.h
index 63817314..b62bd186 100644
--- a/Nuake/src/Window.h
+++ b/Nuake/src/Window.h
@@ -1,11 +1,12 @@
 #pragma once
+
 #include "Core/Core.h"
 #include "Core/Maths.h"
+#include "Core/MulticastDelegate.h"
 #include "Core/Timestep.h"
 
 #include <functional>
 
-
 struct GLFWwindow;
 
 namespace Nuake
@@ -13,6 +14,8 @@ namespace Nuake
 	class Scene;
 	class FrameBuffer;
 
+	DECLARE_MULTICAST_DELEGATE(OnWindowSetSceneDelegate, Ref<Scene>)
+	
 	class Window
 	{
 	public:
@@ -44,7 +47,7 @@ namespace Nuake
 		void Center();
 
 		Ref<Scene> GetScene();
-		bool SetScene(Ref<Scene> scene);
+		bool SetScene(Ref<Scene> newScene);
 
 		void SetTitle(const std::string& title);
 		std::string GetTitle();
@@ -63,6 +66,8 @@ namespace Nuake
 		void SetOnWindowClosedCallback(std::function<void(Window& window)> callback);
 		void SetOnDragNDropCallback(std::function<void(Window&, const std::vector<std::string>& paths)> callback);
 
+		OnWindowSetSceneDelegate& OnWindowSetScene() { return windowSetSceneDelegate; }
+
 	private:
 		const std::string DEFAULT_TITLE = "Untitled Window";
 		const uint32_t DEFAULT_WIDTH = 1280;
@@ -85,6 +90,8 @@ namespace Nuake
 
 		void InitImgui();
 
+		OnWindowSetSceneDelegate windowSetSceneDelegate;
+
 	private:
 	};
 }
diff --git a/NuakeNet/src/EngineSubsystem.cs b/NuakeNet/src/EngineSubsystem.cs
index dfb2eb67..09acd603 100644
--- a/NuakeNet/src/EngineSubsystem.cs
+++ b/NuakeNet/src/EngineSubsystem.cs
@@ -20,6 +20,9 @@
         }
 
         public virtual void Initialize() {}
+        public virtual void OnScenePreInit(Scene scene) {}
+        public virtual void OnScenePostInit(Scene scene) {}
+        public virtual void OnSceneUnloaded(Scene scene) {}
         public virtual void OnTick(float deltaTime) {}
     }
 }