#pragma once

#include "scene/Scene.hpp"

#include <memory>
#include <utility>

/**
 * Owns current scene and supports immediate or queued transitions.
 */
class SceneManager {
  public:
    template <typename T, typename... Args> void ChangeScene(Args &&...args);
    template <typename T, typename... Args> void QueueSceneChange(Args &&...args);

    void ChangeScene(std::unique_ptr<Scene> nextScene);
    void QueueSceneChange(std::unique_ptr<Scene> nextScene);
    void Update(float dt);
    void Draw();

  private:
    std::unique_ptr<Scene> current;
    std::unique_ptr<Scene> queued;
};

inline void SceneManager::ChangeScene(std::unique_ptr<Scene> nextScene) {
    if (current) {
        current->Exit();
    }
    current = std::move(nextScene);
    if (current) {
        current->Enter();
    }
}

inline void SceneManager::QueueSceneChange(std::unique_ptr<Scene> nextScene) {
    queued = std::move(nextScene);
}

inline void SceneManager::Update(float dt) {
    if (queued) {
        ChangeScene(std::move(queued));
    }
    if (current) {
        current->Update(dt);
    }
    if (queued) {
        ChangeScene(std::move(queued));
    }
}

inline void SceneManager::Draw() {
    if (current) {
        current->Draw();
    }
}

template <typename T, typename... Args> inline void SceneManager::ChangeScene(Args &&...args) {
    ChangeScene(std::make_unique<T>(*this, std::forward<Args>(args)...));
}

template <typename T, typename... Args> inline void SceneManager::QueueSceneChange(Args &&...args) {
    QueueSceneChange(std::make_unique<T>(*this, std::forward<Args>(args)...));
}