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

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
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.com.fasterxml.jackson.databind.node.ObjectNode;
import org.gcube.informationsystem.base.reference.AccessType;
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.Relation;
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.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.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.utils.PropagationConstraintOrient;
import org.gcube.informationsystem.resourceregistry.utils.Utility;
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>>
		extends RelationElementManagement<ResourceManagement, T>{
	
	/**
	 * Used in AddToContext. The Relation must add/check also the source entity
	 */
	public boolean checkContextOfSourceEntity;
	
	public void setCheckContextOfSourceEntity(boolean checkContextOfSourceEntity) {
		this.checkContextOfSourceEntity = checkContextOfSourceEntity;
	}

	public final PropagationConstraint defaultPropagationConstraint;
	
	protected RelationManagement(AccessType accessType, Class<? extends Entity> targetEntityClass, PropagationConstraint defaultPropagationConstraint) {
		super(accessType, Resource.class, targetEntityClass);
		this.defaultPropagationConstraint = defaultPropagationConstraint;
		this.checkContextOfSourceEntity = false;
	}
	
	protected RelationManagement(AccessType accessType, Class<? extends Entity> targetEntityClass, SecurityContext workingContext, ODatabaseDocument orientGraph,
			PropagationConstraint defaultPropagationConstraint) {
		this(accessType, targetEntityClass, defaultPropagationConstraint);
		this.oDatabaseDocument = orientGraph;
		setWorkingContext(workingContext);
	}
	
	/*
	 * Needed for ResourceManagement.serializeAsJson() function to check that
	 * sourceEntityManagement is the same of the instance is creating this
	 * RelationManagement. TODO Look for a workaround
	 */
	public ResourceManagement giveMeSourceEntityManagementAsIs() throws ResourceRegistryException {
		return sourceEntityManagement;
	}
	
	public ResourceManagement getSourceEntityManagement() throws ResourceRegistryException {
		if(sourceEntityManagement == null) {
			OVertex source = getElement().getVertex(ODirection.OUT);
			sourceEntityManagement = newSourceEntityManagement();
			sourceEntityManagement.setElement(source);
		}
		sourceEntityManagement.setReload(reload);
		return sourceEntityManagement;
	}
	
	public T getTargetEntityManagement() throws ResourceRegistryException {
		if(targetEntityManagement == null) {
			OVertex target = getElement().getVertex(ODirection.IN);
			targetEntityManagement = newTargetEntityManagement();
			targetEntityManagement.setElement(target);
		}
		targetEntityManagement.setReload(reload);
		return targetEntityManagement;
	}
	
	public void setSourceEntityManagement(ResourceManagement resourceManagement) {
		this.sourceEntityManagement = resourceManagement;
	}
	
	public void setTargetEntityManagement(T targetEntityManagement) {
		this.targetEntityManagement = targetEntityManagement;
	}
	
	@Override
	public String serialize() throws ResourceRegistryException {
		return serializeAsJson().toString();
	}
	
	@Override
	public JsonNode serializeAsJson() throws ResourceRegistryException {
		return serializeAsJson(true, true);
	}
	
	public JsonNode serializeAsJson(boolean includeSource, boolean includeTarget) throws ResourceRegistryException {
		JsonNode relation = serializeSelfOnly();
		
		try {
			if(includeSource) {
				EntityManagement<? extends Resource> sourceEntityManagement = getSourceEntityManagement();
				((ObjectNode) relation).replace(Relation.SOURCE_PROPERTY, sourceEntityManagement.serializeSelfOnly());
			}
			
			if(includeTarget) {
				EntityManagement<? extends Entity> targetEntityManagement = getTargetEntityManagement();
				((ObjectNode) relation).replace(Relation.TARGET_PROPERTY, targetEntityManagement.serializeAsJson());
			}
			
		} catch(ResourceRegistryException e) {
			logger.error("Unable to correctly serialize {}. {}", element, Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE, e);
			throw e;
		} catch(Exception e) {
			logger.error("Unable to correctly serialize {}. {}", element, Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE, e);
			throw new ResourceRegistryException(e);
		}
		
		return relation;
	}
	
	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.serializeAsJson();
			} else if(this instanceof ConsistsOfManagement) {
				sourceResource = resourceManagement.serializeSelfOnly();
			} 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, serializeAsJson());
		} else if(this instanceof ConsistsOfManagement) {
			sourceResource = ResourceManagement.addConsistsOf(sourceResource, serializeAsJson());
		} 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.warn("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.warn("Unable to get {}. Default value ({}) will be used", RemoveConstraint.class.getSimpleName(),
					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.info("{} successfully created", elementType);
		
		return element;
	}
	
	protected ResourceManagement newSourceEntityManagement() throws ResourceRegistryException {
		return new ResourceManagement(getWorkingContext(), oDatabaseDocument);
	}
	
	protected abstract T newTargetEntityManagement() throws ResourceRegistryException;
	
	@Override
	protected OEdge reallyUpdate() throws ResourceRegistryException {
		
		logger.debug("Trying to update {} : {}", elementType, jsonNode);
		
		OEdge edge = getElement();
		ElementManagement.updateProperties(oClass, edge, jsonNode, ignoreKeys, ignoreStartWithKeys);
		
		if(accessType.compareTo(AccessType.CONSISTS_OF) == 0) {
			JsonNode target = jsonNode.get(Relation.TARGET_PROPERTY);
			if(target != null) {
				FacetManagement fm = new FacetManagement(getWorkingContext(), oDatabaseDocument);
				fm.setJsonNode(target);
				fm.internalUpdate();
			}
		}
		
		logger.info("{} {} successfully updated", elementType, jsonNode);
		
		return edge;
		
	}
	
	@Override
	protected Map<UUID,JsonNode> reallyAddToContext(SecurityContext targetSecurityContext)
			throws ContextException, ResourceRegistryException {
		getElement();
		
		Map<UUID,JsonNode> affectedInstances = new HashMap<>();
		
		AddConstraint addConstraint = AddConstraint.unpropagate;
		
		try {
			PropagationConstraint 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.
				 */
				affectedInstances.putAll(getTargetEntityManagement().internalAddToContext(targetSecurityContext));
				
				targetSecurityContext.addElement(getElement(), oDatabaseDocument);
				/* 
				 * DO NOT UNCOMMENT
				 * the instance is added internalAddToContext() function after 
				 * the update of Header metadata i.e. modifiedBy, lastUpdateTime 
				 * affectedInstances.put(uuid, serializeSelfOnly());
				 */
				
				break;
			
			case unpropagate:
				break;
			
			default:
				break;
		}
		
		return affectedInstances;
	}
	
	public Map<UUID,JsonNode> forcedAddToContext(SecurityContext targetSecurityContext)
			throws ContextException, ResourceRegistryException {
		getElement();
		
		Map<UUID,JsonNode> affectedInstances = new HashMap<>();
		
		/* Adding source to Context */
		affectedInstances.putAll(getSourceEntityManagement().internalAddToContext(targetSecurityContext));
		
		/* Adding target to Context */
		affectedInstances.putAll(getTargetEntityManagement().internalAddToContext(targetSecurityContext));
		
		targetSecurityContext.addElement(getElement(), oDatabaseDocument);
		affectedInstances.put(uuid, serializeSelfOnly());
		
		return affectedInstances;
	}
	
	@Override
	protected Map<UUID,JsonNode> reallyRemoveFromContext(SecurityContext targetSecurityContext)
			throws ContextException, ResourceRegistryException {
		getElement();
		
		Map<UUID,JsonNode> affectedInstances = new HashMap<>();
		
		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) {
			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, serializeSelfOnly());
		
		switch(removeConstraint) {
			case cascade:
				affectedInstances.putAll(getTargetEntityManagement().internalRemoveFromContext(targetSecurityContext));
				break;
			
			case cascadeWhenOrphan:
				OVertex target = (OVertex) getTargetEntityManagement().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 {
					affectedInstances.putAll(getTargetEntityManagement().internalRemoveFromContext(targetSecurityContext));
				}
				break;
			
			case keep:
				break;
			
			default:
				break;
		}
		
		return affectedInstances;
	}
	
	@Override
	protected boolean reallyDelete() throws RelationNotFoundException, ResourceRegistryException {
		logger.debug("Going to remove {} with UUID {}. Related {}s will be detached.", accessType.getName(), uuid,
				targetEntityClass.getSimpleName());
		
		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);
		}
		
		OVertex target = getTargetEntityManagement().getElement();
		element.delete();
		
		switch(removeConstraint) {
			case cascade:
				getTargetEntityManagement().internalDelete();
				break;
			
			case cascadeWhenOrphan:
				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;
		}
		
		return true;
	}
	
	@SuppressWarnings("unchecked")
	protected Collection<JsonNode> serializeEdges(Iterable<ODocument> edges, boolean postFilterPolymorphic)
			throws ResourceRegistryException {
		Map<String,JsonNode> visitedSourceResources = new HashMap<>();
		for(ODocument d : edges) {
			OEdge edge = (OEdge) d;
			
			// TODO check because it was using compare
			if(postFilterPolymorphic && getOClass().isSubClassOf(elementType)) {
				continue;
			}
			
			RelationManagement<T> relationManagement = ElementManagementUtility.getRelationManagement(getWorkingContext(),
					oDatabaseDocument, edge);
			visitedSourceResources = relationManagement.fullSerialize(visitedSourceResources);
		}
		return visitedSourceResources.values();
	}
	
	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(elementType, polymorphic);
		Collection<JsonNode> collection = serializeEdges(edges, false);
		return serializeJsonNodeCollectionAsString(collection);
	}
	
	@Override
	public Map<UUID,JsonNode> addToContext(UUID contextUUID) throws NotFoundException, ContextException {
		logger.debug("Going to add {} with UUID {} to Context with UUID {}", accessType.getName(), uuid, contextUUID);
		
		try {
			oDatabaseDocument = ContextUtility.getAdminSecurityContext().getDatabaseDocument(PermissionMode.WRITER);
			
			SecurityContext targetSecurityContext = ContextUtility.getInstance().getSecurityContextByUUID(contextUUID);
			
			Map<UUID,JsonNode> added = forcedAddToContext(targetSecurityContext);
			
			oDatabaseDocument.commit();
			logger.info("{} with UUID {} successfully added to Context with UUID {}", accessType.getName(), uuid,
					contextUUID);
			
			return added;
		} catch(Exception e) {
			logger.error("Unable to add {} with UUID {} to Context with UUID {}", accessType.getName(), uuid,
					contextUUID, e);
			if(oDatabaseDocument != null) {
				oDatabaseDocument.rollback();
			}
			throw new ContextException(e);
		} finally {
			if(oDatabaseDocument != null) {
				oDatabaseDocument.close();
			}
		}
	}
	
}