Extra2D/include/scene/scene_manager.h

#pragma once

#include <core/types.h>
#include <functional>
#include <scene/scene.h>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>


namespace extra2d {

// 前向声明
struct RenderCommand;

// ============================================================================
// 场景管理器 - 管理场景的生命周期和切换
// ============================================================================
class SceneManager {
public:
  // ------------------------------------------------------------------------
  // 单例访问
  // ------------------------------------------------------------------------
  static SceneManager &getInstance();

  // ------------------------------------------------------------------------
  // 场景栈操作
  // ------------------------------------------------------------------------

  // 运行第一个场景
  void runWithScene(IntrusivePtr<Scene> scene);

  // 替换当前场景
  void replaceScene(IntrusivePtr<Scene> scene);

  // 压入新场景（当前场景暂停）
  void pushScene(IntrusivePtr<Scene> scene);

  // 弹出当前场景（恢复上一个场景）
  void popScene();

  // 弹出到根场景
  void popToRootScene();

  // 弹出到指定场景
  void popToScene(const std::string &name);

  // ------------------------------------------------------------------------
  // 获取场景
  // ------------------------------------------------------------------------
  IntrusivePtr<Scene> getCurrentScene() const;
  IntrusivePtr<Scene> getPreviousScene() const;
  IntrusivePtr<Scene> getRootScene() const;

  // 通过名称获取场景
  IntrusivePtr<Scene> getSceneByName(const std::string &name) const;

  // ------------------------------------------------------------------------
  // 查询
  // ------------------------------------------------------------------------
  size_t getSceneCount() const { return sceneStack_.size(); }
  bool isEmpty() const { return sceneStack_.empty(); }
  bool hasScene(const std::string &name) const;

  // ------------------------------------------------------------------------
  // 更新和渲染
  // ------------------------------------------------------------------------
  void update(float dt);
  void render(Renderer &renderer);
  void collectRenderCommands(std::vector<RenderCommand> &commands);

  // ------------------------------------------------------------------------
  // 清理
  // ------------------------------------------------------------------------
  void end();
  void purgeCachedScenes();

public:
  SceneManager() = default;
  ~SceneManager() = default;
  SceneManager(const SceneManager &) = delete;
  SceneManager &operator=(const SceneManager &) = delete;

  // 场景切换（供 Application 使用）
  void enterScene(IntrusivePtr<Scene> scene);

private:
  void doSceneSwitch();
  void dispatchPointerEvents(Scene &scene);

  std::stack<IntrusivePtr<Scene>> sceneStack_;
  std::unordered_map<std::string, IntrusivePtr<Scene>> namedScenes_;

  // Next scene to switch to (queued during transition)
  IntrusivePtr<Scene> nextScene_;
  bool sendCleanupToScene_ = false;

  Node *hoverTarget_ = nullptr;
  Node *captureTarget_ = nullptr;
  Vec2 lastPointerWorld_ = Vec2::Zero();
  bool hasLastPointerWorld_ = false;
};

} // namespace extra2d