UINT32 PrefabUtility::generatePrefabIds(const HSceneObject& sceneObject, UINT32 startingId)
	{
		Stack<HSceneObject> todo;
		todo.push(sceneObject);

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

			for (auto& component : currentSO->mComponents)
			{
				if (component->getLinkId() == (UINT32)-1)
					component->mLinkId = startingId++;
			}

			UINT32 numChildren = (UINT32)currentSO->getNumChildren();
			for (UINT32 i = 0; i < numChildren; i++)
			{
				HSceneObject child = currentSO->getChild(i);

				if (!child->hasFlag(SOF_DontSave))
				{
					if (child->getLinkId() == (UINT32)-1)
						child->mLinkId = startingId++;

					if(child->mPrefabLinkUUID.empty())
						todo.push(currentSO->getChild(i));
				}
			}
		}

		return startingId;
	}
	void PrefabUtility::restoreLinkedInstanceData(const HSceneObject& so, SceneObjectProxy& proxy, 
		UnorderedMap<UINT32, GameObjectInstanceDataPtr>& linkedInstanceData)
	{
		Stack<HSceneObject> todo;
		todo.push(so);

		// Root is not in the instance data map because its link ID belongs to the parent prefab, if any
		so->_setInstanceData(proxy.instanceData);

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

			Vector<HComponent>& components = current->mComponents;
			for (auto& component : components)
			{
				if (component->getLinkId() != (UINT32)-1)
				{
					auto iterFind = linkedInstanceData.find(component->getLinkId());
					if (iterFind != linkedInstanceData.end())
					{
						component->_setInstanceData(iterFind->second);
						component._setHandleData(component.getInternalPtr());
					}
				}
			}

			UINT32 numChildren = current->getNumChildren();
			for (UINT32 i = 0; i < numChildren; i++)
			{
				HSceneObject child = current->getChild(i);

				if (child->getLinkId() != (UINT32)-1)
				{
					auto iterFind = linkedInstanceData.find(child->getLinkId());
					if (iterFind != linkedInstanceData.end())
						child->_setInstanceData(iterFind->second);
				}

				if (child->mPrefabLinkUUID.empty())
					todo.push(child);
			}
		}
	}
	void PrefabUtility::recordInstanceData(const HSceneObject& so, SceneObjectProxy& output,
		UnorderedMap<UINT32, GameObjectInstanceDataPtr>& linkedInstanceData)
	{
		struct StackData
		{
			HSceneObject so;
			SceneObjectProxy* proxy;
		};

		Stack<StackData> todo;
		todo.push({so, &output});

		output.instanceData = so->_getInstanceData();
		output.linkId = (UINT32)-1;

		while (!todo.empty())
		{
			StackData curData = todo.top();
			todo.pop();

			const Vector<HComponent>& components = curData.so->getComponents();
			for (auto& component : components)
			{
				curData.proxy->components.push_back(ComponentProxy());

				ComponentProxy& componentProxy = curData.proxy->components.back();
				componentProxy.instanceData = component->_getInstanceData();
				componentProxy.linkId = component->getLinkId();

				linkedInstanceData[componentProxy.linkId] = componentProxy.instanceData;
			}

			UINT32 numChildren = curData.so->getNumChildren();
			curData.proxy->children.resize(numChildren);

			for (UINT32 i = 0; i < numChildren; i++)
			{
				HSceneObject child = curData.so->getChild(i);

				SceneObjectProxy& childProxy = curData.proxy->children[i];

				childProxy.instanceData = child->_getInstanceData();
				childProxy.linkId = child->getLinkId();

				linkedInstanceData[childProxy.linkId] = childProxy.instanceData;

				if (child->mPrefabLinkUUID.empty())
				{
					todo.push({ child, &curData.proxy->children[i] });
				}
			}
		}
	}
	void PrefabUtility::updateFromPrefab(const HSceneObject& so)
	{
		HSceneObject topLevelObject = so;

		while (topLevelObject != nullptr)
		{
			if (!topLevelObject->mPrefabLinkUUID.empty())
				break;

			if (topLevelObject->mParent != nullptr)
				topLevelObject = topLevelObject->mParent;
			else
				topLevelObject = nullptr;
		}

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

		// Find any prefab instances
		Vector<HSceneObject> prefabInstanceRoots;

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

			if (!current->mPrefabLinkUUID.empty())
				prefabInstanceRoots.push_back(current);

			UINT32 childCount = current->getNumChildren();
			for (UINT32 i = 0; i < childCount; i++)
			{
				HSceneObject child = current->getChild(i);
				todo.push(child);
			}
		}

		// Stores data about the new prefab instance and its original parent and link id
		// (as those aren't stored in the prefab diff)
		struct RestoredPrefabInstance
		{
			HSceneObject newInstance;
			HSceneObject originalParent;
			SPtr<PrefabDiff> diff;
			UINT32 originalLinkId;
		};

		Vector<RestoredPrefabInstance> newPrefabInstanceData;

		// For each prefab instance load its reference prefab from the disk and check if it changed. If it has changed
		// instantiate the prefab and destroy the current instance. Then apply instance specific changes stored in a
		// prefab diff, if any, as well as restore the original parent and link id (link id of the root prefab instance
		// belongs to the parent prefab if any). Finally fix any handles pointing to the old objects so that they now point
		// to the newly instantiated objects. To the outside world it should be transparent that we just destroyed and then
		// re-created from scratch the entire hierarchy.

		// Need to do this bottom up to ensure I don't destroy the parents before children
		for (auto iter = prefabInstanceRoots.rbegin(); iter != prefabInstanceRoots.rend(); ++iter)
		{
			HSceneObject current = *iter;
			HPrefab prefabLink = static_resource_cast<Prefab>(gResources().loadFromUUID(current->mPrefabLinkUUID, false, false));

			if (prefabLink.isLoaded(false) && prefabLink->getHash() != current->mPrefabHash)
			{
				// Save IDs, destroy original, create new, restore IDs
				SceneObjectProxy soProxy;
				UnorderedMap<UINT32, GameObjectInstanceDataPtr> linkedInstanceData;
				recordInstanceData(current, soProxy, linkedInstanceData);

				HSceneObject parent = current->getParent();
				SPtr<PrefabDiff> prefabDiff = current->mPrefabDiff;

				current->destroy(true);
				HSceneObject newInstance = prefabLink->_clone();

				// When restoring instance IDs it is important to make all the new handles point to the old GameObjectInstanceData.
				// This is because old handles will have different GameObjectHandleData and we have no easy way of accessing it to
				// change to which GameObjectInstanceData it points. But the GameObjectManager ensures that all handles deserialized
				// at once (i.e. during the ::instantiate() call above) will share GameObjectHandleData so we can simply replace
				// to what they point to, affecting all of the handles to that object. (In another words, we can modify the
				// new handles at this point, but old ones must keep referencing what they already were.)
				restoreLinkedInstanceData(newInstance, soProxy, linkedInstanceData);
				restoreUnlinkedInstanceData(newInstance, soProxy);

				newPrefabInstanceData.push_back({ newInstance, parent, prefabDiff, newInstance->getLinkId() });
			}
		}

		// Once everything is instantiated, apply diffs, restore old parents & link IDs for root.
		for (auto& entry : newPrefabInstanceData)
		{
			// Diffs must be applied after everything is instantiated and instance data restored since it may contain
			// game object handles within or external to its prefab instance.
			if (entry.diff != nullptr)
				entry.diff->apply(entry.newInstance);

			entry.newInstance->mPrefabDiff = entry.diff;

			entry.newInstance->setParent(entry.originalParent, false);
			entry.newInstance->mLinkId = entry.originalLinkId;
		}

		gResources().unloadAllUnused();
	}
	void PrefabUtility::restoreUnlinkedInstanceData(const HSceneObject& so, SceneObjectProxy& proxy)
	{
		struct StackEntry
		{
			HSceneObject so;
			SceneObjectProxy* proxy;
		};

		Stack<StackEntry> todo;
		todo.push(StackEntry());

		StackEntry& topEntry = todo.top();
		topEntry.so = so;
		topEntry.proxy = &proxy;

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

			if (current.proxy->linkId == -1)
				current.so->_setInstanceData(current.proxy->instanceData);

			Vector<HComponent>& components = current.so->mComponents;
			UINT32 componentProxyIdx = 0;
			UINT32 numComponentProxies = (UINT32)current.proxy->components.size();
			for (auto& component : components)
			{
				if (component->getLinkId() == (UINT32)-1)
				{
					bool foundInstanceData = false;
					for (; componentProxyIdx < numComponentProxies; componentProxyIdx++)
					{
						if (current.proxy->components[componentProxyIdx].linkId != -1)
							continue;

						component->_setInstanceData(current.proxy->components[componentProxyIdx].instanceData);
						component._setHandleData(component.getInternalPtr());

						foundInstanceData = true;
						break;
					}

					assert(foundInstanceData);
				}
			}

			UINT32 numChildren = current.so->getNumChildren();
			UINT32 childProxyIdx = 0;
			UINT32 numChildProxies = (UINT32)current.proxy->children.size();
			for (UINT32 i = 0; i < numChildren; i++)
			{
				HSceneObject child = current.so->getChild(i);

				if (child->getLinkId() == (UINT32)-1)
				{
					bool foundInstanceData = false;
					for (; childProxyIdx < numChildProxies; childProxyIdx++)
					{
						if (current.proxy->children[childProxyIdx].linkId != -1)
							continue;

						assert(current.proxy->children[childProxyIdx].linkId == -1);
						child->_setInstanceData(current.proxy->children[childProxyIdx].instanceData);

						if (child->mPrefabLinkUUID.empty())
						{
							todo.push(StackEntry());

							StackEntry& newEntry = todo.top();
							newEntry.so = child;
							newEntry.proxy = &current.proxy->children[childProxyIdx];
						}

						foundInstanceData = true;
						break;
					}

					assert(foundInstanceData);
				}
				else
				{
					if (!child->mPrefabLinkUUID.empty())
						continue;

					for (UINT32 j = 0; j < numChildProxies; j++)
					{
						if (child->getLinkId() == current.proxy->children[j].linkId)
						{
							todo.push(StackEntry());

							StackEntry& newEntry = todo.top();
							newEntry.so = child;
							newEntry.proxy = &current.proxy->children[j];
							break;
						}
					}
				}
			}
		}
	}
	void CmdBreakPrefab::commit()
	{
		clear();

		if (mSceneObject == nullptr || mSceneObject.isDestroyed())
			return;

		HSceneObject rootObj = mSceneObject;

		while (rootObj != nullptr)
		{
			if (!rootObj->_getPrefabLinkUUID().empty())
				break;

			if (rootObj->getParent() != nullptr)
				rootObj = rootObj->getParent();
			else
				rootObj = nullptr;
		}

		if (rootObj != nullptr)
		{
			mPrefabRoot = rootObj;
			mPrefabLinkUUID = rootObj->_getPrefabLinkUUID();
			mPrefabDiff = rootObj->_getPrefabDiff();

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

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

				const Vector<HComponent>& components = currentSO->getComponents();
				for (auto& component : components)
				{
					UINT32 linkId = component->getLinkId();

					if (linkId != (UINT32)-1)
						mLinkIds[component->getInstanceId()] = linkId;

					mLinkIds[component->getInstanceId()] = component->getLinkId();
				}

				UINT32 numChildren = (UINT32)currentSO->getNumChildren();
				for (UINT32 i = 0; i < numChildren; i++)
				{
					HSceneObject child = currentSO->getChild(i);
					UINT32 linkId = child->getLinkId();

					if (linkId != (UINT32)-1)
						mLinkIds[child->getInstanceId()] = linkId;

					if (child->_getPrefabLinkUUID().empty())
						todo.push(child);
				}
			}
		}

		mSceneObject->breakPrefabLink();
	}
	void PrefabDiff::applyDiff(const SPtr<PrefabObjectDiff>& diff, const HSceneObject& object)
	{
		if ((diff->soFlags & (UINT32)SceneObjectDiffFlags::Name) != 0)
			object->setName(diff->name);

		if ((diff->soFlags & (UINT32)SceneObjectDiffFlags::Position) != 0)
			object->setPosition(diff->position);

		if ((diff->soFlags & (UINT32)SceneObjectDiffFlags::Rotation) != 0)
			object->setRotation(diff->rotation);

		if ((diff->soFlags & (UINT32)SceneObjectDiffFlags::Scale) != 0)
			object->setScale(diff->scale);

		if ((diff->soFlags & (UINT32)SceneObjectDiffFlags::Active) != 0)
			object->setActive(diff->isActive);

		// Note: It is important to remove objects and components first, before adding them.
		//		 Some systems rely on the fact that applyDiff added components/objects are 
		//       always at the end.
		const Vector<HComponent>& components = object->getComponents();
		for (auto& removedId : diff->removedComponents)
		{
			for (auto component : components)
			{
				if (removedId == component->getLinkId())
				{
					component->destroy();
					break;
				}
			}
		}

		for (auto& removedId : diff->removedChildren)
		{
			UINT32 childCount = object->getNumChildren();
			for (UINT32 i = 0; i < childCount; i++)
			{
				HSceneObject child = object->getChild(i);
				if (removedId == child->getLinkId())
				{
					child->destroy();
					break;
				}
			}
		}

		for (auto& addedComponentData : diff->addedComponents)
		{
			BinarySerializer bs;
			SPtr<Component> component = std::static_pointer_cast<Component>(bs._decodeFromIntermediate(addedComponentData));

			object->addAndInitializeComponent(component);
		}

		for (auto& addedChildData : diff->addedChildren)
		{
			BinarySerializer bs;
			SPtr<SceneObject> sceneObject = std::static_pointer_cast<SceneObject>(bs._decodeFromIntermediate(addedChildData));
			sceneObject->setParent(object);

			if(object->isInstantiated())
				sceneObject->_instantiate();
		}

		for (auto& componentDiff : diff->componentDiffs)
		{
			for (auto& component : components)
			{
				if (componentDiff->id == component->getLinkId())
				{
					IDiff& diffHandler = component->getRTTI()->getDiffHandler();
					diffHandler.applyDiff(component.getInternalPtr(), componentDiff->data);
					break;
				}
			}
		}

		for (auto& childDiff : diff->childDiffs)
		{
			UINT32 childCount = object->getNumChildren();
			for (UINT32 i = 0; i < childCount; i++)
			{
				HSceneObject child = object->getChild(i);
				if (childDiff->id == child->getLinkId())
				{
					applyDiff(childDiff, child);
					break;
				}
			}
		}
	}
	void PrefabDiff::renameInstanceIds(const HSceneObject& prefab, const HSceneObject& instance, Vector<RenamedGameObject>& output)
	{
		UnorderedMap<String, UnorderedMap<UINT32, UINT64>> linkToInstanceId;

		struct StackEntry
		{
			HSceneObject so;
			String uuid;
		};

		// When renaming it is important to rename the prefab and not the instance, since the diff will otherwise
		// contain prefab's IDs, but will be used for the instance.

		Stack<StackEntry> todo;
		todo.push({ instance, "root" });

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

			String childParentUUID;
			if (current.so->mPrefabLinkUUID.empty())
				childParentUUID = current.uuid;
			else
				childParentUUID = current.so->mPrefabLinkUUID;

			UnorderedMap<UINT32, UINT64>& idMap = linkToInstanceId[childParentUUID];

			const Vector<HComponent>& components = current.so->getComponents();
			for (auto& component : components)
			{
				if (component->getLinkId() != (UINT32)-1)
					idMap[component->getLinkId()] = component->getInstanceId();
			}

			UINT32 numChildren = current.so->getNumChildren();
			for (UINT32 i = 0; i < numChildren; i++)
			{
				HSceneObject child = current.so->getChild(i);

				if (child->getLinkId() != (UINT32)-1)
					idMap[child->getLinkId()] = child->getInstanceId();

				todo.push({ child, childParentUUID });
			}
		}

		// Root has link ID from its parent so we handle it separately
		{
			output.push_back(RenamedGameObject());
			RenamedGameObject& renamedGO = output.back();
			renamedGO.instanceData = instance->mInstanceData;
			renamedGO.originalId = instance->getInstanceId();

			prefab->mInstanceData->mInstanceId = instance->getInstanceId();
		}

		todo.push({ prefab, "root" });
		while (!todo.empty())
		{
			StackEntry current = todo.top();
			todo.pop();

			String childParentUUID;
			if (current.so->mPrefabLinkUUID.empty())
				childParentUUID = current.uuid;
			else
				childParentUUID = current.so->mPrefabLinkUUID;

			auto iterFind = linkToInstanceId.find(childParentUUID);
			if (iterFind != linkToInstanceId.end())
			{
				UnorderedMap<UINT32, UINT64>& idMap = iterFind->second;

				const Vector<HComponent>& components = current.so->getComponents();
				for (auto& component : components)
				{
					auto iterFind2 = idMap.find(component->getLinkId());
					if (iterFind2 != idMap.end())
					{
						output.push_back(RenamedGameObject());
						RenamedGameObject& renamedGO = output.back();
						renamedGO.instanceData = component->mInstanceData;
						renamedGO.originalId = component->getInstanceId();

						component->mInstanceData->mInstanceId = iterFind2->second;
					}
				}
			}

			UINT32 numChildren = current.so->getNumChildren();
			for (UINT32 i = 0; i < numChildren; i++)
			{
				HSceneObject child = current.so->getChild(i);

				if (iterFind != linkToInstanceId.end())
				{
					if (child->getLinkId() != -1)
					{
						UnorderedMap<UINT32, UINT64>& idMap = iterFind->second;

						auto iterFind2 = idMap.find(child->getLinkId());
						if (iterFind2 != idMap.end())
						{
							output.push_back(RenamedGameObject());
							RenamedGameObject& renamedGO = output.back();
							renamedGO.instanceData = child->mInstanceData;
							renamedGO.originalId = child->getInstanceId();

							child->mInstanceData->mInstanceId = iterFind2->second;
						}
					}
				}

				todo.push({ child, childParentUUID });
			}
		}
	}
	SPtr<PrefabObjectDiff> PrefabDiff::generateDiff(const HSceneObject& prefab, const HSceneObject& instance)
	{
		SPtr<PrefabObjectDiff> output;

		if (prefab->getName() != instance->getName())
		{
			if (output == nullptr)
				output = bs_shared_ptr_new<PrefabObjectDiff>();

			output->name = instance->getName();
			output->soFlags |= (UINT32)SceneObjectDiffFlags::Name;
		}

		if (prefab->getPosition() != instance->getPosition())
		{
			if (output == nullptr)
				output = bs_shared_ptr_new<PrefabObjectDiff>();

			output->position = instance->getPosition();
			output->soFlags |= (UINT32)SceneObjectDiffFlags::Position;
		}

		if (prefab->getRotation() != instance->getRotation())
		{
			if (output == nullptr)
				output = bs_shared_ptr_new<PrefabObjectDiff>();

			output->rotation = instance->getRotation();
			output->soFlags |= (UINT32)SceneObjectDiffFlags::Rotation;
		}

		if (prefab->getScale() != instance->getScale())
		{
			if (output == nullptr)
				output = bs_shared_ptr_new<PrefabObjectDiff>();

			output->scale = instance->getScale();
			output->soFlags |= (UINT32)SceneObjectDiffFlags::Scale;
		}

		if (prefab->getActive() != instance->getActive())
		{
			if (output == nullptr)
				output = bs_shared_ptr_new<PrefabObjectDiff>();

			output->isActive = instance->getActive();
			output->soFlags |= (UINT32)SceneObjectDiffFlags::Active;
		}

		UINT32 prefabChildCount = prefab->getNumChildren();
		UINT32 instanceChildCount = instance->getNumChildren();

		// Find modified and removed children
		for (UINT32 i = 0; i < prefabChildCount; i++)
		{
			HSceneObject prefabChild = prefab->getChild(i);

			SPtr<PrefabObjectDiff> childDiff;
			bool foundMatching = false;
			for (UINT32 j = 0; j < instanceChildCount; j++)
			{
				HSceneObject instanceChild = instance->getChild(j);

				if (prefabChild->getLinkId() == instanceChild->getLinkId())
				{
					if (instanceChild->mPrefabLinkUUID.empty())
						childDiff = generateDiff(prefabChild, instanceChild);

					foundMatching = true;
					break;
				}
			}

			if (foundMatching)
			{
				if (childDiff != nullptr)
				{
					if (output == nullptr)
						output = bs_shared_ptr_new<PrefabObjectDiff>();

					output->childDiffs.push_back(childDiff);
				}
			}
			else
			{
				if (output == nullptr)
					output = bs_shared_ptr_new<PrefabObjectDiff>();

				output->removedChildren.push_back(prefabChild->getLinkId());
			}	
		}

		// Find added children
		for (UINT32 i = 0; i < instanceChildCount; i++)
		{
			HSceneObject instanceChild = instance->getChild(i);

			if (instanceChild->hasFlag(SOF_DontSave))
				continue;

			bool foundMatching = false;
			if (instanceChild->getLinkId() != -1)
			{
				for (UINT32 j = 0; j < prefabChildCount; j++)
				{
					HSceneObject prefabChild = prefab->getChild(j);

					if (prefabChild->getLinkId() == instanceChild->getLinkId())
					{
						foundMatching = true;
						break;
					}
				}
			}

			if (!foundMatching)
			{
				BinarySerializer bs;
				SPtr<SerializedObject> obj = bs._encodeToIntermediate(instanceChild.get());

				if (output == nullptr)
					output = bs_shared_ptr_new<PrefabObjectDiff>();

				output->addedChildren.push_back(obj);
			}
		}

		const Vector<HComponent>& prefabComponents = prefab->getComponents();
		const Vector<HComponent>& instanceComponents = instance->getComponents();

		UINT32 prefabComponentCount = (UINT32)prefabComponents.size();
		UINT32 instanceComponentCount = (UINT32)instanceComponents.size();

		// Find modified and removed components
		for (UINT32 i = 0; i < prefabComponentCount; i++)
		{
			HComponent prefabComponent = prefabComponents[i];

			SPtr<PrefabComponentDiff> childDiff;
			bool foundMatching = false;
			for (UINT32 j = 0; j < instanceComponentCount; j++)
			{
				HComponent instanceComponent = instanceComponents[j];

				if (prefabComponent->getLinkId() == instanceComponent->getLinkId())
				{
					BinarySerializer bs;
					SPtr<SerializedObject> encodedPrefab = bs._encodeToIntermediate(prefabComponent.get());
					SPtr<SerializedObject> encodedInstance = bs._encodeToIntermediate(instanceComponent.get());

					IDiff& diffHandler = prefabComponent->getRTTI()->getDiffHandler();
					SPtr<SerializedObject> diff = diffHandler.generateDiff(encodedPrefab, encodedInstance);

					if (diff != nullptr)
					{
						childDiff = bs_shared_ptr_new<PrefabComponentDiff>();
						childDiff->id = prefabComponent->getLinkId();
						childDiff->data = diff;
					}

					foundMatching = true;
					break;
				}
			}

			if (foundMatching)
			{
				if (childDiff != nullptr)
				{
					if (output == nullptr)
						output = bs_shared_ptr_new<PrefabObjectDiff>();

					output->componentDiffs.push_back(childDiff);
				}
			}
			else
			{
				if (output == nullptr)
					output = bs_shared_ptr_new<PrefabObjectDiff>();

				output->removedComponents.push_back(prefabComponent->getLinkId());
			}
		}

		// Find added components
		for (UINT32 i = 0; i < instanceComponentCount; i++)
		{
			HComponent instanceComponent = instanceComponents[i];

			bool foundMatching = false;
			if (instanceComponent->getLinkId() != -1)
			{
				for (UINT32 j = 0; j < prefabComponentCount; j++)
				{
					HComponent prefabComponent = prefabComponents[j];

					if (prefabComponent->getLinkId() == instanceComponent->getLinkId())
					{
						foundMatching = true;
						break;
					}
				}
			}

			if (!foundMatching)
			{
				BinarySerializer bs;
				SPtr<SerializedObject> obj = bs._encodeToIntermediate(instanceComponent.get());

				if (output == nullptr)
					output = bs_shared_ptr_new<PrefabObjectDiff>();

				output->addedComponents.push_back(obj);
			}
		}

		if (output != nullptr)
			output->id = instance->getLinkId();

		return output;
	}