From 5dd3cc1b73a9e65ea14af862141896d25dd46ca3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hatvani=20Tam=C3=A1s?= <hatvanitamas09@gmail.com>
Date: Thu, 9 Apr 2026 22:07:10 +0200
Subject: [PATCH] feat: queuing layer commands such as pop, push and transition
 at the end of each frame

---
 SakuraCore/src/Application.cpp |  3 +++
 SakuraCore/src/Layer.cpp       | 23 +++++++++++++++++------
 SakuraCore/src/LayerStack.cpp  | 32 +++++++++++++++++++++++++++++++-
 SakuraCore/src/LayerStack.h    | 12 ++++++++++++
 4 files changed, 63 insertions(+), 7 deletions(-)

diff --git a/SakuraCore/src/Application.cpp b/SakuraCore/src/Application.cpp
index 9ad5f13..bab04ee 100644
--- a/SakuraCore/src/Application.cpp
+++ b/SakuraCore/src/Application.cpp
@@ -155,6 +155,9 @@ void Application::Run() {
         }
 
         SDL_RenderPresent(m_Renderer);
+
+        // handle layercommands here after each frame
+        m_LayerStack.ProcessCommands();
     }
 }
 
diff --git a/SakuraCore/src/Layer.cpp b/SakuraCore/src/Layer.cpp
index 7f5bf92..91abbdf 100644
--- a/SakuraCore/src/Layer.cpp
+++ b/SakuraCore/src/Layer.cpp
@@ -1,5 +1,6 @@
 #include "Layer.h"
 #include "Application.h"
+#include "LayerStack.h"
 #include <memory>
 #include <string>
 
@@ -8,12 +9,22 @@ Layer::Layer(const std::string &name, bool isActive) : m_LayerName(name), m_isAc
 
 void Layer::QueueTransition(std::unique_ptr<Layer> toLayer) {
     // TODO: redo this based on the event video
+    // basically handle it like the other layer stuff
+    // put it into a vector and go over the list at the end of the application loop
     auto &layerStack = Application::Get().m_LayerStack;
-    for (auto &layer : layerStack) {
-        if (layer.get() == this) {
-            layer = std::move(toLayer);
-            return;
-        }
-    }
+
+    LayerCommand command;
+    command.action = LayerAction::Transition;
+    command.targetLayer = this;
+    command.newLayer = std::move(toLayer);
+
+    layerStack.SubmitCommand(std::move(command));
+
+    // for (auto &layer : layerStack) {
+    //     if (layer.get() == this) {
+    //         layer = std::move(toLayer);
+    //         return;
+    //     }
+    // }
 }
 } // namespace SakuraVNE
diff --git a/SakuraCore/src/LayerStack.cpp b/SakuraCore/src/LayerStack.cpp
index 7c49ac8..bdf3916 100644
--- a/SakuraCore/src/LayerStack.cpp
+++ b/SakuraCore/src/LayerStack.cpp
@@ -7,10 +7,40 @@ namespace SakuraVNE {
 LayerStack::~LayerStack() {
     for (auto &layer : m_LayerStack) {
         layer->OnDetach();
-        // delete layer;
     }
 }
 
+void LayerStack::SubmitCommand(LayerCommand command) { m_CommandQueue.push_back(std::move(command)); }
+
+void LayerStack::ProcessCommands() {
+    if (m_CommandQueue.empty()) {
+        return;
+    }
+
+    for (auto &command : m_CommandQueue) {
+        switch (command.action) {
+        case LayerAction::Pop:
+            PopLayer(command.targetLayer);
+            break;
+        case LayerAction::Push:
+            PushLayer(std::move(command.newLayer));
+            break;
+        case LayerAction::Transition:
+            auto it = std::find_if(m_LayerStack.begin(), m_LayerStack.end(), [&](const std::unique_ptr<Layer> &layer) { return layer.get() == command.targetLayer; });
+
+            if (it != m_LayerStack.end()) {
+                (*it)->OnDetach();
+                command.newLayer->OnAttach();
+
+                *it = std::move(command.newLayer);
+            }
+
+            break;
+        }
+    }
+    m_CommandQueue.clear();
+}
+
 void LayerStack::PushLayer(std::unique_ptr<Layer> layer) {
     m_LayerStack.emplace(m_LayerStack.begin() + m_LayerIndex, std::move(layer));
     m_LayerIndex++;
diff --git a/SakuraCore/src/LayerStack.h b/SakuraCore/src/LayerStack.h
index f4bb8aa..ddcfea4 100644
--- a/SakuraCore/src/LayerStack.h
+++ b/SakuraCore/src/LayerStack.h
@@ -6,6 +6,14 @@
 #include <vector>
 
 namespace SakuraVNE {
+enum class LayerAction { Push, Pop, Transition };
+
+struct LayerCommand {
+    LayerAction action;
+    Layer *targetLayer;
+    std::unique_ptr<Layer> newLayer;
+};
+
 class LayerStack {
 public:
     LayerStack() = default;
@@ -26,11 +34,15 @@ public:
     std::vector<std::unique_ptr<Layer>>::const_reverse_iterator rbegin() const { return m_LayerStack.rbegin(); }
     std::vector<std::unique_ptr<Layer>>::const_reverse_iterator rend() const { return m_LayerStack.rend(); }
 
+    void SubmitCommand(LayerCommand command);
+    void ProcessCommands();
+
 #ifdef DEBUG
     // this is only used for the tests for now, so it will be taken out of the release build
     inline const std::vector<std::unique_ptr<Layer>> &GetLayers() const { return m_LayerStack; }
 #endif
 private:
+    std::vector<LayerCommand> m_CommandQueue;
     std::vector<std::unique_ptr<Layer>> m_LayerStack;
     unsigned int m_LayerIndex = 0;
 };