#include "BsPrefab.h"
#include "BsPrefabRTTI.h"
#include "BsResources.h"
#include "BsSceneObject.h"

namespace BansheeEngine
{
	Prefab::Prefab()
		:Resource(false)
	{
		
	}

	HPrefab Prefab::create(const HSceneObject& sceneObject)
	{
		assert(sceneObject->mPrefabLink != nullptr);

		PrefabPtr newPrefab = createEmpty();
		newPrefab->initialize(sceneObject);

		HPrefab handle = static_resource_cast<Prefab>(gResources()._createResourceHandle(newPrefab));
		sceneObject->mPrefabLink = handle;

		return handle;
	}

	PrefabPtr Prefab::createEmpty()
	{
		PrefabPtr newPrefab = bs_core_ptr<Prefab, PoolAlloc>(new (bs_alloc<Prefab, PoolAlloc>()) Prefab());
		newPrefab->_setThisPtr(newPrefab);

		return newPrefab;
	}

	void Prefab::generatePrefabIds(const HSceneObject& sceneObject)
	{
		Vector<HGameObject> objectsToId;
		Set<INT32> existingIds;

		Stack<HSceneObject> todo;
		todo.push(sceneObject);

		while (!todo.empty())
		{
			HSceneObject currentSO = todo.top();
			todo.pop();

			if (currentSO->mLinkId == -1)
				objectsToId.push_back(currentSO);
			else
				existingIds.insert(currentSO->mLinkId);

			for (auto& component : currentSO->mComponents)
			{
				if (component->mLinkId == -1)
					objectsToId.push_back(component);
				else
					existingIds.insert(component->mLinkId);
			}
		}

		auto setIter = existingIds.begin();
		INT32 nextId = 0;
		for (auto& object : objectsToId)
		{
			INT32 freeId = -1;
			for (; setIter != existingIds.end(); ++setIter)
			{
				if (nextId < (*setIter))
					freeId = nextId++;
				else
					nextId++;
			}

			if (freeId == -1)
				freeId = nextId++;

			object->mLinkId = freeId;
		}		
	}

	void Prefab::initialize(const HSceneObject& sceneObject)
	{
		generatePrefabIds(sceneObject);

		sceneObject->setFlags(SOF_DontInstantiate);
		mRoot = sceneObject->clone();
		sceneObject->unsetFlags(SOF_DontInstantiate);

		// Remove objects with "dont save" flag
		Stack<HSceneObject> todo;
		todo.push(mRoot);

		while (!todo.empty())
		{
			HSceneObject current = todo.top();
			todo.pop();

			if (current->hasFlag(SOF_DontSave))
				current->destroy();
			else
			{
				UINT32 numChildren = current->getNumChildren();
				for (UINT32 i = 0; i < numChildren; i++)
					todo.push(current->getChild(i));
			}
		}
	}

	HSceneObject Prefab::instantiate()
	{
		if (mRoot == nullptr)
			return HSceneObject();

		HSceneObject clone = mRoot->clone();
		clone->instantiate();

		return clone;
	}

	RTTITypeBase* Prefab::getRTTIStatic()
	{
		return PrefabRTTI::instance();
	}

	RTTITypeBase* Prefab::getRTTI() const
	{
		return Prefab::getRTTIStatic();
	}
}