package org.gcube.informationsystem.resourceregistry.instances.model.relations;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.UUID;

import org.gcube.com.fasterxml.jackson.databind.JsonNode;
import org.gcube.com.fasterxml.jackson.databind.ObjectMapper;
import org.gcube.com.fasterxml.jackson.databind.node.ArrayNode;
import org.gcube.informationsystem.base.reference.AccessType;
import org.gcube.informationsystem.base.reference.relations.RelationElement;
import org.gcube.informationsystem.context.reference.entities.Context;
import org.gcube.informationsystem.model.reference.entities.Entity;
import org.gcube.informationsystem.model.reference.entities.Resource;
import org.gcube.informationsystem.model.reference.properties.PropagationConstraint;
import org.gcube.informationsystem.model.reference.properties.PropagationConstraint.AddConstraint;
import org.gcube.informationsystem.model.reference.properties.PropagationConstraint.RemoveConstraint;
import org.gcube.informationsystem.model.reference.relations.ConsistsOf;
import org.gcube.informationsystem.model.reference.relations.Relation;
import org.gcube.informationsystem.resourceregistry.api.contexts.ContextCache;
import org.gcube.informationsystem.resourceregistry.api.exceptions.AvailableInAnotherContextException;
import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
import org.gcube.informationsystem.resourceregistry.api.exceptions.context.ContextException;
import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.RelationNotFoundException;
import org.gcube.informationsystem.resourceregistry.api.exceptions.schema.SchemaViolationException;
import org.gcube.informationsystem.resourceregistry.contexts.ContextUtility;
import org.gcube.informationsystem.resourceregistry.contexts.security.SecurityContext;
import org.gcube.informationsystem.resourceregistry.contexts.security.SecurityContext.PermissionMode;
import org.gcube.informationsystem.resourceregistry.instances.base.ElementManagement;
import org.gcube.informationsystem.resourceregistry.instances.base.ElementManagementUtility;
import org.gcube.informationsystem.resourceregistry.instances.base.relations.RelationElementManagement;
import org.gcube.informationsystem.resourceregistry.instances.model.ERManagement;
import org.gcube.informationsystem.resourceregistry.instances.model.Operation;
import org.gcube.informationsystem.resourceregistry.instances.model.entities.EntityManagement;
import org.gcube.informationsystem.resourceregistry.instances.model.entities.FacetManagement;
import org.gcube.informationsystem.resourceregistry.instances.model.entities.ResourceManagement;
import org.gcube.informationsystem.resourceregistry.types.TypesCache;
import org.gcube.informationsystem.resourceregistry.utils.HeaderUtility;
import org.gcube.informationsystem.resourceregistry.utils.PropagationConstraintOrient;
import org.gcube.informationsystem.resourceregistry.utils.Utility;
import org.gcube.informationsystem.types.reference.entities.EntityType;
import org.gcube.informationsystem.types.reference.entities.ResourceType;
import org.gcube.informationsystem.types.reference.relations.RelationType;
import org.gcube.informationsystem.utils.ElementMapper;

import com.orientechnologies.orient.core.db.document.ODatabaseDocument;
import com.orientechnologies.orient.core.metadata.schema.OType;
import com.orientechnologies.orient.core.record.ODirection;
import com.orientechnologies.orient.core.record.OEdge;
import com.orientechnologies.orient.core.record.OVertex;
import com.orientechnologies.orient.core.record.impl.ODocument;

/**
 * @author Luca Frosini (ISTI - CNR)
 */
public abstract class RelationManagement<T extends EntityManagement<? extends Entity, TET>, TET extends EntityType>
		extends RelationElementManagement<ResourceManagement, T, ResourceType, TET> implements ERManagement {
	
	/**
	 * The source context of an addToContex
	 */
	protected SecurityContext sourceSecurityContext;
	
	/**
	 * The target context of an addToContex/RemoveFromContext
	 */
	protected SecurityContext targetSecurityContext;
	
	/**
	 * By the default the system honour the propagation constraints 
	 * so this variable is initialised as true.
	 * 
	 * To revert a previous operation or for particular a maintenance
	 * we could request to the service do not honour the propagation 
	 * constraints but under certain conditions and with some limitation 
	 * only. 
	 * These limitation are required to keep the system in a consistent
	 * state.
	 * In fact, this directive is only valid for Resources and IsRelatedTo
	 * relations. We need to take in account that to add an
	 * IsRelatedTo to a context always the source and target 
	 * Resources must be in such a Context.
	 * Please also take into account that adding a Resource 
	 * to a context always imply to honour the propagation constraints
	 * of ConsistsOf relations. In fact, a resource must be characterised
	 * least by one facet in any context it belongs. Giving that we
	 * cannot made assumption on which facets must be used. 
	 * A way could be to consider just the facets are mandatory for such a 
	 * Resource Type, but the type could not have mandatory facets 
	 * (even every Resource Type in the gCube Model has one mandatory facet).
	 * As counterpart, when a Resource is removed from a Context all the facets
	 * charactering it must be removed.
	 * 
	 * This option can also be used in conjunction with 
	 * {@link ElementManagement#dryRun}=true. 
	 * This allow to simulate a sharing operation which requires 
	 * do not honour the propagation constraints.
	 */
	protected boolean honourPropagationConstraintsInContextSharing;
	
	@Override
	public void setSourceSecurityContext(SecurityContext sourceSecurityContext) {
		this.sourceSecurityContext = sourceSecurityContext;
	}
	
	@Override
	public SecurityContext getSourceSecurityContext() {
		return sourceSecurityContext;
	}
	
	@Override
	public void setTargetSecurityContext(SecurityContext targetSecurityContext) {
		this.targetSecurityContext = targetSecurityContext;
	}
	
	@Override
	public SecurityContext getTargetSecurityContext() {
		return sourceSecurityContext;
	}
	
	@Override
	public boolean isHonourPropagationConstraintsInContextSharing() {
		return honourPropagationConstraintsInContextSharing;
	}

	@Override
	public void setHonourPropagationConstraintsInContextSharing(boolean honourPropagationConstraintsInContextSharing) {
		this.honourPropagationConstraintsInContextSharing = honourPropagationConstraintsInContextSharing;
	}
	
	public final PropagationConstraint defaultPropagationConstraint;
	
	public boolean isAvailableOnContext(SecurityContext securityContext) {
		try {
			return securityContext.isElementInContext(element);
		} catch (ResourceRegistryException e) {
			return false;
		}
	}
	
	protected RelationManagement(AccessType accessType, Class<? extends Entity> targetEntityClass, PropagationConstraint defaultPropagationConstraint) {
		super(accessType, Resource.class, targetEntityClass);
		this.defaultPropagationConstraint = defaultPropagationConstraint;
		
		/*
		 * By the default the system honour the propagation constraints 
		 * so this variable is initialised as true.
		 */
		this.honourPropagationConstraintsInContextSharing = true;
		
		this.skipped = false;
		
	}
	
	protected PropagationConstraint propagationConstraint;
	
	/* Indicate that AddToContext skipped the isntance because it was not the source context */
	protected boolean skipped; 
	
	@Override
	public OEdge getElement() throws NotFoundException, AvailableInAnotherContextException, ResourceRegistryException {
		try {
			element = super.getElement();
		} catch(NotFoundException e) {
			try {
				retrieveElementFromAnyContext();
				throw getSpecificAvailableInAnotherContextException(typeName == null ? accessType.getName()
						: typeName + " with UUID " + uuid + " is available in another "
								+ Context.class.getSimpleName());
			} catch(AvailableInAnotherContextException e1) {
				throw e1;
			} catch(Exception e1) {
				throw e;
			}
		} catch(ResourceRegistryException e) {
			throw e;
		} catch(Exception e) {
			throw new ResourceRegistryException(e);
		}
		return element;
	}
	
	/*
	 * Needed for ResourceManagement.serializeAsJson() function to check that
	 * sourceEntityManagement is the same of the instance is creating this
	 * RelationManagement.
	 */
	public ResourceManagement giveMeSourceEntityManagementAsIs() throws ResourceRegistryException {
		return sourceEntityManagement;
	}
	
	protected Map<String,JsonNode> fullSerialize(Map<String,JsonNode> visitedSourceResources)
			throws ResourceRegistryException {
		
		OVertex source = getElement().getVertex(ODirection.OUT);
		
		String id = source.getIdentity().toString();
		
		JsonNode sourceResource = visitedSourceResources.get(id);
		ResourceManagement resourceManagement = null;
		
		if(sourceResource == null) {
			resourceManagement = (ResourceManagement) ElementManagementUtility.getEntityManagement(getWorkingContext(),
					oDatabaseDocument, source);
			if(this instanceof IsRelatedToManagement) {
				sourceResource = resourceManagement.createCompleteJsonNode();
			} else if(this instanceof ConsistsOfManagement) {
				if(includeSource) {
					sourceResource = resourceManagement.serializeSelfAsJsonNode();
				}
			} else {
				String error = String.format("{%s is not a %s nor a %s. %s", this,
						IsRelatedToManagement.class.getSimpleName(), ConsistsOfManagement.class.getSimpleName(),
						Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
				throw new ResourceRegistryException(error);
			}
		}
		
		if(this instanceof IsRelatedToManagement) {
			sourceResource = ResourceManagement.addIsRelatedTo(sourceResource, serializeAsJsonNode());
		} else if(this instanceof ConsistsOfManagement) {
			sourceResource = ResourceManagement.addConsistsOf(sourceResource, serializeAsJsonNode());
		} else {
			String error = String.format("{%s is not a %s nor a %s. %s", this,
					IsRelatedToManagement.class.getSimpleName(), ConsistsOfManagement.class.getSimpleName(),
					Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
			throw new ResourceRegistryException(error);
		}
		
		visitedSourceResources.put(id, sourceResource);
		
		return visitedSourceResources;
	}
	
	protected PropagationConstraintOrient getPropagationConstraint(ODocument oDocument)
			throws ResourceRegistryException {
		
		PropagationConstraintOrient propagationConstraintOrient = new PropagationConstraintOrient();
		
		PropagationConstraint propagationConstraint = null;
		
		if(oDocument == null) {
			propagationConstraint = defaultPropagationConstraint;
		} else if(oDocument instanceof PropagationConstraintOrient) {
			propagationConstraint = (PropagationConstraint) oDocument;
		} else {
			try {
				propagationConstraint = ElementMapper.unmarshal(PropagationConstraint.class, oDocument.toJSON());
			} catch(Exception e) {
				logger.warn("Unable to recreate {}. {}", PropagationConstraint.NAME,
						Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
			}
		}
		
		AddConstraint addConstraint = propagationConstraint.getAddConstraint();
		if(addConstraint == null) {
			addConstraint = defaultPropagationConstraint.getAddConstraint();
			logger.debug("Unable to get {}. Default value ({}) will be used", AddConstraint.class.getSimpleName(),
					addConstraint);
		}
		propagationConstraintOrient.setAddConstraint(addConstraint);
		
		RemoveConstraint removeConstraint = propagationConstraint.getRemoveConstraint();
		if(removeConstraint == null) {
			removeConstraint = defaultPropagationConstraint.getRemoveConstraint();
			logger.debug("Unable to get {}. Default value ({}) will be used", RemoveConstraint.class.getSimpleName(),
					removeConstraint);
		}else {
			if (this instanceof ConsistsOfManagement && removeConstraint == RemoveConstraint.keep) {
				removeConstraint = defaultPropagationConstraint.getRemoveConstraint();
				logger.warn("A {} cannot use {}.{}. Default value ({}) will be used", ConsistsOf.NAME,
						RemoveConstraint.class.getSimpleName(), RemoveConstraint.keep, removeConstraint);

			}
		}
		propagationConstraintOrient.setRemoveConstraint(removeConstraint);
		
		return propagationConstraintOrient;
	}
	
	protected void checkPropagationConstraint() throws ResourceRegistryException {
		Object object = getElement().getProperty(Relation.PROPAGATION_CONSTRAINT_PROPERTY);
		PropagationConstraintOrient pc = getPropagationConstraint((ODocument) object);
		getElement().setProperty(Relation.PROPAGATION_CONSTRAINT_PROPERTY, pc, OType.EMBEDDED);
	}
	
	@Override
	protected OEdge reallyCreate() throws ResourceRegistryException {
		element = super.reallyCreate();
		
		checkPropagationConstraint();
		
		logger.trace("{} successfully created", typeName);
		
		return element;
	}
	
	@Override
	protected ResourceManagement newSourceEntityManagement() throws ResourceRegistryException {
		ResourceManagement resourceManagement = new ResourceManagement();
		resourceManagement.setWorkingContext(getWorkingContext());
		resourceManagement.setODatabaseDocument(oDatabaseDocument);
		return resourceManagement;
	}
	
	protected String getEntityTypeNotValidErrroMessage(String entityPosition, String requiredType, String effectiveType) {
		StringBuffer stringBuffer = new StringBuffer();
		stringBuffer.append("The ");
		stringBuffer.append(entityPosition);
		stringBuffer.append(" instance of the relation ");
		stringBuffer.append(typeName);
		stringBuffer.append(" is of type ");
		stringBuffer.append(effectiveType);
		stringBuffer.append(" which is not a specialisation of ");
		stringBuffer.append(requiredType);
		stringBuffer.append(".");
		return stringBuffer.toString();
	}
	
	@Override
	protected void checksourceAndTargetEntityCompliancy() throws NotFoundException, AvailableInAnotherContextException, SchemaViolationException, ResourceRegistryException {
		String sourceType = sourceEntityManagement.getTypeName();
		String targetType = targetEntityManagement.getTypeName();
		
		RelationType<ResourceType, TET> relationType = getCachedType().getType();
		
		ResourceType resourceType = relationType.getSource();
		TET tet = relationType.getTarget();
		
		String requiredSourceType = resourceType.getName();
		String requiredTargetType = tet.getName();
		
		TypesCache typesCache = TypesCache.getInstance();
		
		if(!typeSatified(typesCache, requiredSourceType, sourceType)) {
			String message = getEntityTypeNotValidErrroMessage(RelationElement.SOURCE_PROPERTY, requiredSourceType, sourceType);
			throw new SchemaViolationException(message);
		}
		
		if(!typeSatified(typesCache, requiredTargetType, targetType)) {
			String message = getEntityTypeNotValidErrroMessage(RelationElement.TARGET_PROPERTY, requiredTargetType, targetType);
			throw new SchemaViolationException(message);
		}
	}
	
	@Override
	protected OEdge reallyUpdate() throws ResourceRegistryException {
		
		logger.trace("Trying to update {} with UUID {}", typeName, uuid);
		logger.trace("Trying to update {} : {}", typeName, jsonNode);
		
		OEdge edge = getElement();
		updateProperties(oClass, edge, jsonNode, ignoreKeys, ignoreStartWithKeys);
		
		if(accessType.compareTo(AccessType.CONSISTS_OF) == 0) {
			JsonNode target = jsonNode.get(Relation.TARGET_PROPERTY);
			if(target != null) {
				FacetManagement facetManagement = new FacetManagement();
				facetManagement.setWorkingContext(getWorkingContext());
				facetManagement.setODatabaseDocument(oDatabaseDocument);
				facetManagement.setJsonNode(target);
				facetManagement.internalUpdate();
			}
		}
		
		logger.info("{} with UUID {} successfully updated", typeName, uuid);
		logger.trace("{} {} successfully updated", typeName, jsonNode);
		
		return edge;
		
	}
	
	protected void reallyAddToContext()
			throws ContextException, ResourceRegistryException {
		if(!sourceSecurityContext.isElementInContext(getElement())) {
			// The element in not in the source security context. It will be skipped
			skipped = true;
			return;
		}
		
		if(honourPropagationConstraintsInContextSharing) {
			AddConstraint addConstraint = AddConstraint.unpropagate;
			
			try {
				propagationConstraint = Utility.getPropertyDocument(PropagationConstraint.class, element,
						Relation.PROPAGATION_CONSTRAINT_PROPERTY);
				if(propagationConstraint.getAddConstraint() != null) {
					addConstraint = propagationConstraint.getAddConstraint();
				} else {
					String error = String.format("%s.%s in %s is null. %s", Relation.PROPAGATION_CONSTRAINT_PROPERTY,
							PropagationConstraint.ADD_PROPERTY, Utility.toJsonString(element, true),
							Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
					logger.error(error);
					throw new ResourceRegistryException(error);
				}
			} catch(Exception e) {
				String error = String.format("Error while getting %s from %s while performing AddToContext. %s",
						Relation.PROPAGATION_CONSTRAINT_PROPERTY, Utility.toJsonString(element, true),
						Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
				logger.warn(error);
				throw new ResourceRegistryException(error, e);
			}
			
			switch(addConstraint) {
				case propagate:
					/*
					 * The relation must be added only in the case the target vertex must be added.
					 * Otherwise we have a relation which point to an entity outside of the context.
					 */
					getTargetEntityManagement().setDryRun(dryRun);
					targetEntityManagement.setHonourPropagationConstraintsInContextSharing(honourPropagationConstraintsInContextSharing);
					targetEntityManagement.setSourceSecurityContext(sourceSecurityContext);
					targetEntityManagement.setTargetSecurityContext(targetSecurityContext);
					targetEntityManagement.internalAddToContext();
					affectedInstances.putAll(targetEntityManagement.getAffectedInstances());
					
					targetSecurityContext.addElement(getElement(), oDatabaseDocument);
					
					/* 
					 * DO NOT UNCOMMENT
					 * // affectedInstances.put(uuid, serializeSelfOnly());
					 * the relation instance is added in internalAddToContext() function after 
					 * the update of Header metadata i.e. modifiedBy, lastUpdateTime 
					 */
					
					break;
				
				case unpropagate:
					break;
				
				default:
					break;
			}
		}else {
			targetSecurityContext.addElement(getElement(), oDatabaseDocument);
			/* 
			 * DO NOT UNCOMMENT
			 * // affectedInstances.put(uuid, serializeSelfOnly());
			 * the relation instance is added in internalAddToContext() function after 
			 * the update of Header metadata i.e. modifiedBy, lastUpdateTime 
			 */
		}
	}
	
	@Override
	public void internalAddToContext()
			throws ContextException, ResourceRegistryException {
		try {
			operation = Operation.ADD_TO_CONTEXT;
			reallyAddToContext();
			if(!skipped && propagationConstraint.getAddConstraint()==PropagationConstraint.AddConstraint.propagate) {
				HeaderUtility.updateModifiedByAndLastUpdate(element);
				element.save();
				affectedInstances.put(uuid, serializeAsAffectedInstance());
			}
		} catch(ResourceRegistryException e) {
			throw e;
		} catch(Exception e) {
			throw new ResourceRegistryException(
					"Error Adding " + typeName + " to " + targetSecurityContext.toString(), e.getCause());
		}
	}
	
	public void forcedAddToContext()
			throws ContextException, ResourceRegistryException {
		setOperation(Operation.ADD_TO_CONTEXT);
		
		/* Adding source to Context */
		getSourceEntityManagement().setDryRun(dryRun);
		sourceEntityManagement.setHonourPropagationConstraintsInContextSharing(honourPropagationConstraintsInContextSharing);
		sourceEntityManagement.setTargetSecurityContext(targetSecurityContext);
		sourceEntityManagement.internalAddToContext();
		affectedInstances.putAll(sourceEntityManagement.getAffectedInstances());
		
		/* Adding target to Context */
		getTargetEntityManagement().setDryRun(dryRun);
		targetEntityManagement.setHonourPropagationConstraintsInContextSharing(honourPropagationConstraintsInContextSharing);
		targetEntityManagement.setTargetSecurityContext(targetSecurityContext);
		targetEntityManagement.internalAddToContext();
		affectedInstances.putAll(targetEntityManagement.getAffectedInstances());
		
		targetSecurityContext.addElement(getElement(), oDatabaseDocument);
		
		affectedInstances.put(uuid, serializeAsAffectedInstance());
	}
	
	@Override
	public void addToContext(UUID contextUUID) throws SchemaViolationException, NotFoundException, ContextException, ResourceRegistryException {
		String contextFullName = ContextCache.getInstance().getContextFullNameByUUID(contextUUID);
		logger.debug("Going to add {} with UUID {} to Context with UUID {} (i.e {})", accessType.getName(), uuid, contextUUID, contextFullName);
		ODatabaseDocument current = ContextUtility.getCurrentODatabaseDocumentFromThreadLocal();
		try {
			workingContext = ContextUtility.getAdminSecurityContext();
			oDatabaseDocument = workingContext.getDatabaseDocument(PermissionMode.WRITER);
			setAsEntryPoint();
			
			sourceSecurityContext = ContextUtility.getCurrentSecurityContext();
			targetSecurityContext = ContextUtility.getInstance().getSecurityContextByUUID(contextUUID);
			
			forcedAddToContext();
			
			sanityCheck();
			
			if(!dryRun) {
				oDatabaseDocument.commit();
			}else {
				oDatabaseDocument.rollback();
			}
			logger.info("{} with UUID {} successfully added to Context with UUID {} (i.e {})", accessType.getName(), uuid, contextUUID, contextFullName);
		} catch(Exception e) {
			logger.error("Unable to add {} with UUID {} to Context with UUID {} (i.e. {})", accessType.getName(), uuid,
					contextUUID, contextFullName, e);
			if(oDatabaseDocument != null) {
				oDatabaseDocument.rollback();
			}
			throw new ContextException(e);
		} finally {
			if(oDatabaseDocument != null) {
				oDatabaseDocument.close();
			}
			
			if(current!=null) {
				current.activateOnCurrentThread();
			}
		}
	}
	
	protected Map<UUID,JsonNode> reallyRemoveFromContext()
			throws ContextException, ResourceRegistryException {
		if(!targetSecurityContext.isElementInContext(getElement())) {
			// The element in not in the source security context. It will be skipped
			return affectedInstances;
		}
		
		getSourceEntityManagement().getElement();
		
		RemoveConstraint removeConstraint = RemoveConstraint.keep;
		
		try {
			propagationConstraint = Utility.getPropertyDocument(PropagationConstraint.class, element,
					Relation.PROPAGATION_CONSTRAINT_PROPERTY);
			if(propagationConstraint.getRemoveConstraint() != null) {
				removeConstraint = propagationConstraint.getRemoveConstraint();
			} else {
				String error = String.format("%s.%s in %s is null. %s", Relation.PROPAGATION_CONSTRAINT_PROPERTY,
						PropagationConstraint.REMOVE_PROPERTY, Utility.toJsonString(element, true),
						Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
				logger.error(error);
				throw new ResourceRegistryException(error);
			}
		} catch(Exception e) {
			String error = String.format("Error while getting %s from %s while performing RemoveFromContext. %s",
					Relation.PROPAGATION_CONSTRAINT_PROPERTY, Utility.toJsonString(element, true),
					Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
			logger.error(error);
			throw new ResourceRegistryException(error, e);
			
		}
		
		/*
		 * In any removeConstraint value the relation MUST be removed from context to
		 * avoid to have edge having a source outside of the context.
		 */
		targetSecurityContext.removeElement(getElement(), oDatabaseDocument);
		
		affectedInstances.put(uuid, serializeAsAffectedInstance());
		
		T targetEntityManagement = getTargetEntityManagement();
		targetEntityManagement.setDryRun(dryRun);
		targetEntityManagement.setHonourPropagationConstraintsInContextSharing(honourPropagationConstraintsInContextSharing);
		// Not needed targetEntityManagement.setSourceSecurityContext(sourceSecurityContext);
		targetEntityManagement.setTargetSecurityContext(targetSecurityContext);
		if(targetEntityManagement instanceof ResourceManagement) {
			((ResourceManagement) targetEntityManagement).setSanityCheckNotRequired();
		}
		switch(removeConstraint) {
			case cascade:
				targetEntityManagement.internalRemoveFromContext();
				affectedInstances.putAll(targetEntityManagement.getAffectedInstances());
				break;
			
			case cascadeWhenOrphan:
				OVertex target = (OVertex) targetEntityManagement.getElement();
				
				Iterable<OEdge> iterable = target.getEdges(ODirection.IN);
				Iterator<OEdge> iterator = iterable.iterator();
				int count = 0;
				OEdge edge = null;
				while(iterator.hasNext()) {
					edge = (OEdge) iterator.next();
					OEdge thisOEdge = (OEdge) getElement();
					if(edge.compareTo(thisOEdge) != 0) {
						if(thisOEdge.getVertex(ODirection.OUT).compareTo(edge.getVertex(ODirection.OUT)) != 0) {
							count++;
							break;
						}
						/*
						 * else{ ContextUtility.removeFromActualContext(orientGraph, edge); }
						 */
					}
				}
				
				if(count > 0) {
					logger.trace(
							"{} point to {} which is not orphan ({} exists). Giving {} directive, it will be not remove from {}.",
							element, target, edge, removeConstraint, targetSecurityContext);
				} else {
					targetEntityManagement.internalRemoveFromContext();
					affectedInstances.putAll(targetEntityManagement.getAffectedInstances());
				}
				break;
			
			case keep:
				break;
			
			default:
				break;
		}
		
		return affectedInstances;
	}
	
	@Override
	public void internalRemoveFromContext()
			throws ContextException, ResourceRegistryException {
		try {
			setOperation(Operation.REMOVE_FROM_CONTEXT);
			reallyRemoveFromContext();
			HeaderUtility.updateModifiedByAndLastUpdate(element);
			element.save();
			affectedInstances.put(uuid, serializeAsAffectedInstance());
		} catch(ResourceRegistryException e) {
			throw e;
		} catch(Exception e) {
			throw new ResourceRegistryException(
					"Error Removing " + typeName + " from " + targetSecurityContext.toString(), e.getCause());
		}
	}
	
	@Override
	public void removeFromContext(UUID contextUUID)
			throws NotFoundException, ContextException, ResourceRegistryException {
		logger.debug("Going to remove {} with UUID {} from Context with UUID {}", typeName, uuid, contextUUID);
		ODatabaseDocument current = ContextUtility.getCurrentODatabaseDocumentFromThreadLocal();
		try {
			workingContext = ContextUtility.getAdminSecurityContext();
			oDatabaseDocument = workingContext.getDatabaseDocument(PermissionMode.WRITER);
			oDatabaseDocument.begin();
			setAsEntryPoint();
			
			
			// Not needed sourceSecurityContext = ContextUtility.getCurrentSecurityContext();
			targetSecurityContext = ContextUtility.getInstance().getSecurityContextByUUID(contextUUID);
			
			internalRemoveFromContext();
			
			sanityCheck();
			
			if(!dryRun) {
				oDatabaseDocument.commit();
			}else {
				oDatabaseDocument.rollback();
			}
			logger.info("{} with UUID {} successfully removed from Context with UUID {}", typeName, uuid, contextUUID);
		} catch(ResourceRegistryException e) {
			logger.error("Unable to remove {} with UUID {} from Context with UUID {}", typeName, uuid, contextUUID);
			if(oDatabaseDocument != null) {
				oDatabaseDocument.rollback();
			}
			throw e;
		} catch(Exception e) {
			logger.error("Unable to remove {} with UUID {} from Context with UUID {}", typeName, uuid, contextUUID,
					e);
			if(oDatabaseDocument != null) {
				oDatabaseDocument.rollback();
			}
			throw new ContextException(e);
		} finally {
			if(oDatabaseDocument != null) {
				oDatabaseDocument.close();
			}
			
			if(current!=null) {
				current.activateOnCurrentThread();
			}
		}
	}
	
	@Override
	protected void reallyDelete() throws RelationNotFoundException, ResourceRegistryException {
		logger.debug("Going to remove {} with UUID {}. Related {}s will be detached.", accessType.getName(), uuid,
				targetEntityClass.getSimpleName());
		
		getElement();
		
		getSourceEntityManagement().getElement();
		
		RemoveConstraint removeConstraint = RemoveConstraint.keep;
		
		try {
			PropagationConstraint propagationConstraint = Utility.getPropertyDocument(PropagationConstraint.class,
					element, Relation.PROPAGATION_CONSTRAINT_PROPERTY);
			if(propagationConstraint.getRemoveConstraint() != null) {
				removeConstraint = propagationConstraint.getRemoveConstraint();
			} else {
				String error = String.format("%s.%s in %s is null. %s", Relation.PROPAGATION_CONSTRAINT_PROPERTY,
						PropagationConstraint.REMOVE_PROPERTY, Utility.toJsonString(element, true),
						Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
				logger.error(error);
				throw new ResourceRegistryException(error);
			}
		} catch(Exception e) {
			logger.warn("Error while getting {} from {}. Assuming {}. {}", Relation.PROPAGATION_CONSTRAINT_PROPERTY,
					Utility.toJsonString(element, true), removeConstraint, Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
		}
		
		// pre-loading target entity because after deleting the relation we will not be able to get it
		T t = getTargetEntityManagement();
		if(targetEntityManagement instanceof ResourceManagement) {
			((ResourceManagement) targetEntityManagement).setSanityCheckNotRequired();
		}
		
		affectedInstances.put(uuid, serializeAsAffectedInstance());
		element.delete();
		
		switch(removeConstraint) {
			case cascade:
				t.internalDelete();
				break;
			
			case cascadeWhenOrphan:
				OVertex target  = t.getElement();
				Iterable<OEdge> iterable = target.getEdges(ODirection.IN);
				Iterator<OEdge> iterator = iterable.iterator();
				if(iterator.hasNext()) {
					logger.trace("{} point to {} which is not orphan. Giving {} directive, it will be keep.", element,
							target, removeConstraint);
				} else {
					getTargetEntityManagement().internalDelete();
				}
				break;
			
			case keep:
				break;
			
			default:
				break;
		}
		
		affectedInstances.putAll(t.getAffectedInstances());
		
	}
	
	protected Collection<JsonNode> serializeEdges(Iterable<ODocument> edges, boolean postFilterPolymorphic)
			throws ResourceRegistryException {
		// Map<String,JsonNode> visitedSourceResources = new HashMap<>();
		List<JsonNode> serilizedEdges = new ArrayList<>();
		for(ODocument d : edges) {
			OEdge edge = (OEdge) d;
			
			if(postFilterPolymorphic && getOClass().isSubClassOf(typeName)) {
				continue;
			}
			
			RelationManagement<?, ?> relationManagement = ElementManagementUtility.getRelationManagement(getWorkingContext(),
					oDatabaseDocument, edge);
			// visitedSourceResources = relationManagement.fullSerialize(visitedSourceResources);
			serilizedEdges.add(relationManagement.serializeAsJsonNode());
		}
		return serilizedEdges;
	}
	
	protected String serializeJsonNodeCollectionAsString(Collection<JsonNode> collection) throws ResourceRegistryException {
		try {
			ObjectMapper objectMapper = new ObjectMapper();
			ArrayNode arrayNode = objectMapper.valueToTree(collection);
			return objectMapper.writeValueAsString(arrayNode);
		} catch(Exception e) {
			throw new ResourceRegistryException(e);
		}
	}
	
	@Override
	public String reallyGetAll(boolean polymorphic) throws ResourceRegistryException {
		Iterable<ODocument> edges = oDatabaseDocument.browseClass(typeName, polymorphic);
		Collection<JsonNode> collection = serializeEdges(edges, false);
		return serializeJsonNodeCollectionAsString(collection);
	}
	
}