Dawn/src/dawn/scene/SceneItem.hpp

// Copyright (c) 2022 Dominic Masters
// 
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT

#pragma once
#include "display/Transform.hpp"
#include "event/Event.hpp"
#include "scene/Scene.hpp"
#include "util/array.hpp"

namespace Dawn {
  class SceneItemComponent;

  class SceneItem {
    private:
      std::vector<SceneItemComponent*> components;

    public:
      Scene *scene;
      sceneitemid_t id;
      Transform transform;

      /**
       * Constructor for a SceneItem. Scene Items should only be called and
       * initialized by the scene itself.
       * 
       * @param scene Weak pointer to the Scene that this SceneItem belongs to.
       * @param id Scene Item ID that the Scene assigned this SceneItem.
       */
      SceneItem(Scene *scene, sceneitemid_t id);
      
      /**
       * Called by the Scene the frame after we were constructed so we can begin
       * existing.
       */
      void init();

      /**
       * Called by the Scene when cleanup needs to occur but before anything in
       * the scene has been disposed.
       */
      void destroy();

      /**
       * Adds a component to this scene item. Components will only have their
       * init methods invoked on the first frame we enter the scene. If you add
       * a component to this item after this time you will either need to try
       * manually invoking its' init method, or ensure the component is aware of
       * the entire SceneItem lifecycle and listen for added callbacks.
       * 
       * @tparam T Type of component being added to this scene item.
       * @return A shared pointer to the newly added component.
       */
      template<class T>
      T * addComponent() {
        auto component = new T(this);
        assertNotNull(component);
        this->components.push_back(component);
        return component;
      }

      /**
       * Returns a component attached to this SceneItem. This method will return
       * either a shared pointer to the component, or nullptr if the item does
       * not have the queried component.
       * 
       * @tparam T Type of component to be fetched.
       * @return A shared pointer to the component, or nullptr if not found.
       */
      template<class T>
      T * getComponent() {
        auto it = this->components.begin();
        while(it != this->components.end()) {
          T *castedAs = dynamic_cast<T*>(*it);
          if(castedAs != nullptr) return castedAs;
          ++it;
        }
        return nullptr;
      }

      /**
       * Finds a (direct) child of this component that has a matching component.
       * 
       * @tparam T Component to find child of.
       * @return Pointer to the child, or nullptr if not found.
       */
      template<class T>
      T * findChild() {
        auto it = this->transform.children.begin();
        while(it != this->transform.children.end()) {
          auto child = (*it)->item->getComponent<T>();
          if(child != nullptr) return child;
          ++it;
        }
        return nullptr;
      }

      /**
       * Finds all (direct) children of this component that match the queried
       * component.
       * 
       * @tparam T Component to find children for.
       * @return Array of pointers to matching children.
       */
      template<class T>
      std::vector<T*> findChildren() {
        auto it = this->transform.children.begin();
        std::vector<T*> children;
        while(it != this->transform.children.end()) {
          auto child = (*it)->item->getComponent<T>();
          if(child != nullptr) children.push_back(child);
          ++it;
        }
        return children;
      }

      /**
       * Finds all children, and children of children, recursively that match
       * the queried component.
       * 
       * @tparam T Component Type to find.
       * @return Array of pointers to matching children components.
       */
      template<class T>
      std::vector<T*> findChildrenDeep() {
        std::vector<Transform*> transformsToCheck = this->transform.children;
        std::vector<T*> itemsFound;

        while(transformsToCheck.size() > 0) {
          auto tras = transformsToCheck.begin();
          vectorAppend(&transformsToCheck, (*tras)->children);
          auto component = (*tras)->item->getComponent<T>();
          if(component != nullptr) itemsFound.push_back(component);
          transformsToCheck.erase(tras);
        }

        return itemsFound;
      }
      
      /**
       * Destroy this SceneItem.
       */
      ~SceneItem();
  };
}