SceneManager.hpp

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#pragma once
 
#include "Assert.hpp"
#include "Log/Log.hpp"
#include "NonCopyable.hpp"
 
#include <memory>
#include <mutex>
#include <typeindex>
#include <unordered_map>


class Scene : public NonCopyable<>
{
public:
 
    virtual ~Scene() = default;

    virtual void Update(const float deltaT) = 0;

    virtual void Draw() const;

    virtual void OnEnter();

    virtual void OnExit();
};

class SceneManager
{
public:

    template <typename SceneT, typename... Args>
        requires std::is_base_of_v<Scene, SceneT>
    void AddScene(Args&&... args)
    {
        auto ptr = std::make_unique<SceneT>(std::forward<Args>(args)...);
 
        std::unique_lock lock(m_mutex);
 
        m_scenes.emplace(typeid(SceneT), std::move(ptr));
    }

    template <typename SceneT>
        requires std::is_base_of_v<Scene, SceneT>
    void RemoveScene()
    {
        std::unique_lock lock(m_mutex);
 
        auto it = m_scenes.find(typeid(SceneT));
        if (it != m_scenes.end())
        {
            Assert(it->second.get() != m_currentScene, "Cannot delete the current scene");
 
            m_scenes.erase(it);
        }
    }

    template <typename SceneT>
        requires std::is_base_of_v<Scene, SceneT>
    void ChangeScene()
    {
        std::unique_lock lock(m_mutex);
 
        auto it = m_scenes.find(typeid(SceneT));
        Assert(it != m_scenes.end(), "Scene ", Demangle<SceneT>().c_str(), " does not exist");
        Assert(it->second.get() != m_currentScene, "Cannot change to the current scene");
 
        m_nextSceneType = typeid(SceneT);
        m_changeScene = true;
    }

    void ClearScenes();
 
private:

    void Update(const float deltaT);

    void Draw();

    void CheckForChange();
 
    Scene* m_currentScene = nullptr;
 
    bool m_changeScene = false;
    std::type_index m_nextSceneType = typeid(void);
 
    std::mutex m_mutex;
 
    std::unordered_map<std::type_index, std::unique_ptr<Scene>> m_scenes;
 
    friend class Engine;
};