/**
 * 
 */
package org.gcube.informationsystem.resourceregistry.er.relation;

import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.UUID;

import org.codehaus.jettison.json.JSONException;
import org.codehaus.jettison.json.JSONObject;
import org.gcube.informationsystem.model.embedded.Header;
import org.gcube.informationsystem.model.embedded.PropagationConstraint;
import org.gcube.informationsystem.model.embedded.PropagationConstraint.AddConstraint;
import org.gcube.informationsystem.model.embedded.PropagationConstraint.RemoveConstraint;
import org.gcube.informationsystem.model.entity.Entity;
import org.gcube.informationsystem.model.entity.Facet;
import org.gcube.informationsystem.model.entity.Resource;
import org.gcube.informationsystem.model.relation.ConsistsOf;
import org.gcube.informationsystem.model.relation.IsRelatedTo;
import org.gcube.informationsystem.model.relation.Relation;
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.SchemaNotFoundException;
import org.gcube.informationsystem.resourceregistry.context.ContextUtility;
import org.gcube.informationsystem.resourceregistry.context.SecurityContextMapper;
import org.gcube.informationsystem.resourceregistry.context.SecurityContextMapper.PermissionMode;
import org.gcube.informationsystem.resourceregistry.er.ERManagement;
import org.gcube.informationsystem.resourceregistry.er.entity.EntityManagement;
import org.gcube.informationsystem.resourceregistry.er.entity.FacetManagement;
import org.gcube.informationsystem.resourceregistry.er.entity.ResourceManagement;
import org.gcube.informationsystem.resourceregistry.schema.SchemaManagementImpl;
import org.gcube.informationsystem.resourceregistry.utils.HeaderUtility;
import org.gcube.informationsystem.resourceregistry.utils.Utility;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.tinkerpop.blueprints.Direction;
import com.tinkerpop.blueprints.Edge;
import com.tinkerpop.blueprints.Vertex;
import com.tinkerpop.blueprints.impls.orient.OrientBaseGraph;
import com.tinkerpop.blueprints.impls.orient.OrientEdge;
import com.tinkerpop.blueprints.impls.orient.OrientEdgeType;
import com.tinkerpop.blueprints.impls.orient.OrientGraph;

/**
 * @author Luca Frosini (ISTI - CNR)
 * 
 */
@SuppressWarnings("rawtypes")
public abstract class RelationManagement<R extends Relation> {

	private static Logger logger = LoggerFactory
			.getLogger(RelationManagement.class);

	public final Set<String> ignoreKeys;
	public final Set<String> ignoreStartWithKeys;

	public static final String AT = "@";
	public static final String UNDERSCORE = "_";

	protected final Class<R> relationClass;
	protected final String baseType;
	protected final Class<? extends Entity> targetEntityClass;

	protected OrientGraph orientGraph;

	protected UUID uuid;
	protected JsonNode jsonNode;
	protected String relationType;
	protected Edge edge;

	protected RelationManagement(Class<R> relationClass) {
		this.ignoreKeys = new HashSet<String>();
		this.ignoreKeys.add(Relation.HEADER_PROPERTY);
		this.ignoreKeys.add(Relation.TARGET_PROPERTY);
		this.ignoreKeys.add(Relation.SOURCE_PROPERTY);
		this.ignoreKeys.add(OrientBaseGraph.CONNECTION_IN.toLowerCase());
		this.ignoreKeys.add(OrientBaseGraph.CONNECTION_OUT.toLowerCase());
		this.ignoreKeys.add(OrientBaseGraph.CONNECTION_IN.toUpperCase());
		this.ignoreKeys.add(OrientBaseGraph.CONNECTION_OUT.toUpperCase());

		this.ignoreStartWithKeys = new HashSet<String>();
		this.ignoreStartWithKeys.add(AT);
		this.ignoreStartWithKeys.add(UNDERSCORE);

		this.relationClass = relationClass;

		if (ConsistsOf.class.isAssignableFrom(relationClass)) {
			this.baseType = ConsistsOf.NAME;
			this.targetEntityClass = Facet.class;
		} else if (IsRelatedTo.class.isAssignableFrom(relationClass)) {
			this.baseType = IsRelatedTo.NAME;
			this.targetEntityClass = Resource.class;
		} else {
			this.baseType = Relation.NAME;
			this.targetEntityClass = Resource.class;
		}
	}

	protected RelationManagement(Class<R> relationClass, OrientGraph orientGraph) {
		this(relationClass);
		this.orientGraph = orientGraph;
	}

	public void setEdge(Edge edge) {
		this.edge = edge;
	}

	public void setUUID(UUID uuid) throws ResourceRegistryException {
		this.uuid = uuid;
		if (jsonNode != null) {
			checkUUIDMatch();
		}
	}

	protected void checkJSON() throws ResourceRegistryException {
		if (uuid == null) {
			try {
				uuid = org.gcube.informationsystem.impl.utils.Utility
						.getUUIDFromJsonNode(jsonNode);
			} catch (Exception e) {

			}
		} else {
			checkUUIDMatch();
		}

		if (this.relationType == null) {
			this.relationType = ERManagement.getClassProperty(jsonNode);
		} else {
			checkEntityMatch();
		}
	}

	public void setJSON(JsonNode jsonNode) throws ResourceRegistryException {
		this.jsonNode = jsonNode;
		checkJSON();
	}

	public void setJSON(String jsonRepresentation)
			throws ResourceRegistryException {
		ObjectMapper mapper = new ObjectMapper();
		try {
			this.jsonNode = mapper.readTree(jsonRepresentation);
		} catch (IOException e) {
			throw new ResourceRegistryException(e);
		}

		checkJSON();
	}

	public void setRelationType(String relationType)
			throws ResourceRegistryException {
		this.relationType = relationType;
		if (relationType == null || relationType.compareTo("") == 0) {
			if (ConsistsOf.class.isAssignableFrom(relationClass)) {
				this.relationType = ConsistsOf.NAME;
			} else if (IsRelatedTo.class.isAssignableFrom(relationClass)) {
				this.relationType = IsRelatedTo.NAME;
			}
		}
		if (jsonNode != null) {
			checkEntityMatch();
		}
	}

	protected void checkEntityMatch() throws ResourceRegistryException {
		String type = ERManagement.getClassProperty(jsonNode);
		if (type != null && type.compareTo(relationType) != 0) {
			String error = String
					.format("Declared resourceType does not match with json representation %s!=%s",
							relationType, type);
			logger.trace(error);
			throw new ResourceRegistryException(error);
		}

		try {
			SchemaManagementImpl.getTypeSchema(relationType, baseType);
		} catch (SchemaNotFoundException e) {
			throw e;
		}
	}

	protected void checkUUIDMatch() throws ResourceRegistryException {
		Header header = null;
		try {
			header = HeaderUtility.getHeader(jsonNode, false);
		} catch (Exception e) {
			throw new ResourceRegistryException(e);
		}

		if (header != null) {
			UUID resourceUUID = header.getUUID();
			if (resourceUUID.compareTo(uuid) != 0) {
				String error = String
						.format("UUID provided in header (%s) differs from the one (%s) used to identify the %s instance",
								resourceUUID.toString(), uuid.toString(),
								relationType);
				throw new ResourceRegistryException(error);

			}
		}
	}

	public Edge getEdge() throws ResourceRegistryException {
		try {
			if (edge == null) {
				edge = Utility.getElementByUUID(orientGraph,
						relationType == null ? baseType : relationType, uuid,
						Edge.class);
			}
			return edge;
		} catch (ResourceRegistryException e) {
			throw new RelationNotFoundException(e);
		}
	}

	public String serialize() throws ResourceRegistryException {
		return serializeAsJson().toString();
	}

	public JSONObject serializeAsJson() throws ResourceRegistryException {
		JSONObject ret = Utility.toJsonObject((OrientEdge) getEdge(), false);

		Vertex vertex = edge.getVertex(Direction.IN);
		EntityManagement entityManagement = EntityManagement
				.getEntityManagement(orientGraph, vertex);

		try {
			ret.put(Relation.TARGET_PROPERTY,
					entityManagement.serializeAsJson());
		} catch (JSONException e) {
			new ResourceRegistryException(e);
		}

		return ret;
	}

	public Edge reallyCreate(UUID sourceUUID, UUID targetUUID)
			throws ResourceRegistryException {
		ResourceManagement srmSource = new ResourceManagement(orientGraph);
		srmSource.setUUID(sourceUUID);
		Vertex source = srmSource.getVertex();

		EntityManagement entityManagement = getEntityManagement();
		entityManagement.setUUID(targetUUID);
		Vertex target = entityManagement.getVertex();

		return reallyCreate(source, target);

	}

	protected Edge reallyCreate(Vertex source, Vertex target)
			throws ResourceRegistryException {

		EntityManagement sourceEntityManagement = EntityManagement
				.getEntityManagement(orientGraph, source);
		EntityManagement targetEntityManagement = EntityManagement
				.getEntityManagement(orientGraph, target);
		if (!(sourceEntityManagement instanceof ResourceManagement)) {
			String error = String.format(
					"Any type of %s can have only a %s as %s. "
							+ "Cannot instatiate %s beetween %s -> %s ",
					Relation.NAME, Resource.NAME, Relation.SOURCE_PROPERTY,
					relationType, sourceEntityManagement.serialize(),
					targetEntityManagement.serialize());
			throw new ResourceRegistryException(error);
		}

		if (this instanceof IsRelatedToManagement) {
			if (!(targetEntityManagement instanceof ResourceManagement)) {
				String error = String.format("A %s can have only a %s as %s. "
						+ "Cannot instatiate %s beetween %s -> %s ", baseType,
						Resource.NAME, Relation.TARGET_PROPERTY, relationType,
						sourceEntityManagement.serialize(),
						targetEntityManagement.serialize());
				throw new ResourceRegistryException(error);
			}
		} else if (this instanceof ConsistsOfManagement) {
			if (!(targetEntityManagement instanceof FacetManagement)) {
				String error = String.format("A %s can have only a %s as %s. "
						+ "Cannot instatiate %s beetween %s -> %s ", baseType,
						Facet.NAME, Relation.TARGET_PROPERTY, relationType,
						sourceEntityManagement.serialize(),
						targetEntityManagement.serialize());
				throw new ResourceRegistryException(error);
			}
		} else {
			String error = String.format("{%s is not a %s nor a %s. "
					+ "This is really strange and should not occur. "
					+ "Please Investigate it.", this,
					IsRelatedToManagement.class.getSimpleName(),
					ConsistsOfManagement.class.getSimpleName());
			throw new ResourceRegistryException(error);
		}

		logger.trace("Creating {} beetween {} -> {}", relationType,
				sourceEntityManagement.serialize(),
				targetEntityManagement.serialize());

		edge = orientGraph.addEdge(null, source, target, relationType);

		ERManagement.updateProperties(edge, jsonNode, ignoreKeys,
				ignoreStartWithKeys);

		HeaderUtility.addHeader(edge, null);
		ContextUtility.addToActualContext(orientGraph, edge);

		((OrientEdge) edge).save();

		logger.info("{} successfully created", relationType);

		return edge;
	}

	public Edge reallyCreate(Vertex source) throws ResourceRegistryException {
		Vertex target = null;
		EntityManagement entityManagement = getEntityManagement();

		if (!jsonNode.has(Relation.TARGET_PROPERTY)) {
			throw new ResourceRegistryException(
					"Error while creating relation. No target definition found");
		}
		entityManagement.setJSON(jsonNode.get(Relation.TARGET_PROPERTY));
		try {
			target = entityManagement.getVertex();
		} catch (Exception e) {
			target = entityManagement.reallyCreate();
		}
		return reallyCreate(source, target);
	}

	public Edge reallyCreate(UUID sourceUUID) throws ResourceRegistryException {
		ResourceManagement srmSource = new ResourceManagement(orientGraph);
		srmSource.setUUID(sourceUUID);
		Vertex source = srmSource.getVertex();
		return reallyCreate(source);
	}

	public Edge reallyUpdate() throws ResourceRegistryException {

		logger.debug("Trying to update {} : {}", relationType, jsonNode);

		Edge edge = getEdge();
		ERManagement.updateProperties(edge, jsonNode, ignoreKeys, ignoreStartWithKeys);

		if (ConsistsOf.class.isAssignableFrom(relationClass)) {
			JsonNode target = jsonNode.get(Relation.TARGET_PROPERTY);
			if (target != null) {
				FacetManagement fm = new FacetManagement(orientGraph);
				fm.setJSON(target);
				fm.reallyUpdate();
			}
		}

		logger.info("{} {} successfully updated", relationType, jsonNode);

		return edge;

	}

	public boolean reallyAddToContext() throws ContextException,
			ResourceRegistryException {
		getEdge();
		
		AddConstraint addConstraint = AddConstraint.unpropagate;

		try {
			PropagationConstraint propagationConstraint = Utility.getEmbedded(
					PropagationConstraint.class, edge,
					Relation.PROPAGATION_CONSTRAINT);
			if (propagationConstraint.getAddConstraint() != null) {
				addConstraint = propagationConstraint.getAddConstraint();
			}
		} catch (Exception e) {
			logger.warn("Error while getting {} from {}. Assuming {}. "
					+ "This is really strange and should not occur. "
					+ "Please Investigate it.",
					Relation.PROPAGATION_CONSTRAINT,
					Utility.toJsonString(edge, true), addConstraint);
		}

		Vertex target = edge.getVertex(Direction.IN);

		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.
				 */
				ContextUtility.addToActualContext(orientGraph, getEdge());
				EntityManagement entityManagement = EntityManagement
						.getEntityManagement(orientGraph, target);
				entityManagement.reallyAddToContext();
				break;
	
			case unpropagate:
				break;
	
			default:
				break;
		}

		return true;
	}

	protected boolean removeFromContextTargetVertex(Vertex target)
			throws ResourceRegistryException {
		EntityManagement entityManagement = EntityManagement
				.getEntityManagement(orientGraph, target);
		if (entityManagement != null) {
			entityManagement.reallyRemoveFromContext();
			return true;
		} else {
			return false;
		}
	}

	public boolean reallyRemoveFromContext() throws ContextException,
			ResourceRegistryException {
		getEdge();

		RemoveConstraint removeConstraint = RemoveConstraint.keep;

		try {
			PropagationConstraint propagationConstraint = Utility.getEmbedded(
					PropagationConstraint.class, edge,
					Relation.PROPAGATION_CONSTRAINT);
			if (propagationConstraint.getRemoveConstraint() != null) {
				removeConstraint = propagationConstraint.getRemoveConstraint();
			}
		} catch (Exception e) {
			logger.warn("Error while getting {} from {}. Assuming {}. "
					+ "This is really strange and should not occur. "
					+ "Please Investigate it.",
					Relation.PROPAGATION_CONSTRAINT,
					Utility.toJsonString(edge, true), removeConstraint);
		}

		Vertex target = edge.getVertex(Direction.IN);
		
		/*
		 * In any removeConstraint value the relation MUSt be removed from
		 * context to avoid to have edge having a source outside of the context.
		 */
		ContextUtility.removeFromActualContext(orientGraph, edge);

		switch (removeConstraint) {
			case cascade:
				removeFromContextTargetVertex(target);
				break;
	
			case cascadeWhenOrphan:
				Iterable<Edge> iterable = target.getEdges(Direction.IN);
				Iterator<Edge> iterator = iterable.iterator();
				if (iterator.hasNext()) {
					logger.trace(
							"{} point to {} which is not orphan. Giving {} directive, it will be not remove from current context.",
							edge, target, removeConstraint);
				} else {
					removeFromContextTargetVertex(target);
				}
				break;
	
			case keep:
				break;
	
			default:
				break;
		}

		return true;
	}

	protected EntityManagement getEntityManagement()
			throws ResourceRegistryException {
		EntityManagement entityManagement;
		if (ConsistsOf.class.isAssignableFrom(relationClass)) {
			entityManagement = new FacetManagement(orientGraph);
		} else if (IsRelatedTo.class.isAssignableFrom(relationClass)) {
			entityManagement = new ResourceManagement(orientGraph);
		} else {
			String error = String.format("{%s is not a %s nor a %s. "
					+ "This is really strange ad should not occur. "
					+ "Please Investigate it.", relationClass, ConsistsOf.NAME,
					IsRelatedTo.NAME);
			throw new ResourceRegistryException(error);
		}
		return entityManagement;
	}

	public static RelationManagement getRelationManagement(
			OrientGraph orientGraph, Edge edge)
			throws ResourceRegistryException {
		OrientEdgeType orientEdgeType = ((OrientEdge) edge).getType();
		RelationManagement relationManagement = null;
		if (orientEdgeType.isSubClassOf(ConsistsOf.NAME)) {
			relationManagement = new ConsistsOfManagement(orientGraph);
		} else if (orientEdgeType.isSubClassOf(IsRelatedTo.NAME)) {
			relationManagement = new IsRelatedToManagement(orientGraph);
		} else {
			String error = String.format("{%s is not a %s nor a %s. "
					+ "This is really strange ad should not occur. "
					+ "Please Investigate it.", edge, ConsistsOf.NAME,
					IsRelatedTo.NAME);
			throw new ResourceRegistryException(error);
		}
		relationManagement.setEdge(edge);
		return relationManagement;
	}

	protected boolean deleteTargetVertex(Vertex target)
			throws ResourceRegistryException {
		EntityManagement entityManagement = EntityManagement
				.getEntityManagement(orientGraph, target);
		if (entityManagement != null) {
			entityManagement.reallyDelete();
			return true;
		} else {
			return false;
		}
	}

	public boolean reallyDelete() throws RelationNotFoundException,
			ResourceRegistryException {
		getEdge();

		RemoveConstraint removeConstraint = RemoveConstraint.keep;

		try {
			PropagationConstraint propagationConstraint = Utility.getEmbedded(
					PropagationConstraint.class, edge,
					Relation.PROPAGATION_CONSTRAINT);
			if (propagationConstraint.getRemoveConstraint() != null) {
				removeConstraint = propagationConstraint.getRemoveConstraint();
			}
		} catch (Exception e) {
			logger.warn("Error while getting {} from {}. Assuming {}. "
					+ "This is really strange and should not occur. "
					+ "Please Investigate it.",
					Relation.PROPAGATION_CONSTRAINT,
					Utility.toJsonString(edge, true), removeConstraint);
		}

		Vertex target = edge.getVertex(Direction.IN);
		edge.remove();

		switch (removeConstraint) {
		case cascade:
			deleteTargetVertex(target);
			break;

		case cascadeWhenOrphan:
			Iterable<Edge> iterable = target.getEdges(Direction.IN);
			Iterator<Edge> iterator = iterable.iterator();
			if (iterator.hasNext()) {
				logger.trace(
						"{} point to {} which is not orphan. Giving {} directive, it will be keep.",
						edge, target, removeConstraint);
			} else {
				deleteTargetVertex(target);
			}
			break;

		case keep:
			break;

		default:
			break;
		}

		return true;
	}

	public String create(UUID sourceUUID, UUID targetUUID)
			throws ResourceRegistryException {
		try {
			orientGraph = ContextUtility
					.getActualSecurityContextGraph(PermissionMode.WRITER);

			edge = reallyCreate(sourceUUID, targetUUID);

			orientGraph.commit();

			return serialize();

		} catch (ResourceRegistryException e) {
			if (orientGraph != null) {
				orientGraph.rollback();
			}
			throw e;
		} catch (Exception e) {
			if (orientGraph != null) {
				orientGraph.rollback();
			}
			throw new ResourceRegistryException(e);
		} finally {
			if (orientGraph != null) {
				orientGraph.shutdown();
			}
		}
	}

	public String read() throws RelationNotFoundException,
			ResourceRegistryException {
		try {

			orientGraph = ContextUtility
					.getActualSecurityContextGraph(PermissionMode.WRITER);

			return serialize();

		} catch (ResourceRegistryException e) {
			if (orientGraph != null) {
				orientGraph.rollback();
			}
			throw e;
		} catch (Exception e) {
			if (orientGraph != null) {
				orientGraph.rollback();
			}
			throw new ResourceRegistryException(e);
		} finally {
			if (orientGraph != null) {
				orientGraph.shutdown();
			}
		}
	}

	public String update() throws RelationNotFoundException,
			ResourceRegistryException {
		try {

			orientGraph = ContextUtility
					.getActualSecurityContextGraph(PermissionMode.WRITER);

			edge = reallyUpdate();

			return serialize();

		} catch (ResourceRegistryException e) {
			if (orientGraph != null) {
				orientGraph.rollback();
			}
			throw e;
		} catch (Exception e) {
			if (orientGraph != null) {
				orientGraph.rollback();
			}
			throw new ResourceRegistryException(e);
		} finally {
			if (orientGraph != null) {
				orientGraph.shutdown();
			}
		}
	}

	public boolean delete() throws RelationNotFoundException,
			ResourceRegistryException {

		logger.debug(
				"Going to remove {} with UUID {}. Related {}s will be detached.",
				baseType, uuid, targetEntityClass.getSimpleName());

		try {
			orientGraph = ContextUtility
					.getActualSecurityContextGraph(PermissionMode.WRITER);

			boolean deleted = reallyDelete();

			orientGraph.commit();

			logger.info("{} {} with UUID {} successfully removed.", baseType,
					uuid);

			return deleted;

		} catch (ResourceRegistryException e) {
			logger.error("Unable to remove {} with UUID.", baseType, uuid);
			if (orientGraph != null) {
				orientGraph.rollback();
			}
			throw e;
		} catch (Exception e) {
			logger.error("Unable to remove {} with UUID {}.", baseType, uuid);
			if (orientGraph != null) {
				orientGraph.rollback();
			}
			throw new ResourceRegistryException(e);
		} finally {
			if (orientGraph != null) {
				orientGraph.shutdown();
			}
		}

	}

	public boolean addToContext() throws ContextException {
		logger.debug("Going to add {} with UUID {} to actual Context",
				baseType, uuid);

		try {
			orientGraph = SecurityContextMapper.getSecurityContextFactory(
					SecurityContextMapper.ADMIN_SECURITY_CONTEXT_UUID,
					PermissionMode.WRITER).getTx();

			boolean added = reallyAddToContext();

			orientGraph.commit();
			logger.info("{} with UUID {} successfully added to actual Context",
					baseType, uuid);

			return added;
		} catch (Exception e) {
			logger.error("Unable to add {} with UUID {} to actual Context",
					baseType, uuid, e);
			if (orientGraph != null) {
				orientGraph.rollback();
			}
			throw new ContextException(e);
		} finally {
			if (orientGraph != null) {
				orientGraph.shutdown();
			}
		}
	}

	public boolean removeFromContext() throws ContextException {
		logger.debug("Going to remove {} with UUID {} from actual Context",
				baseType, uuid);

		try {
			orientGraph = SecurityContextMapper.getSecurityContextFactory(
					SecurityContextMapper.ADMIN_SECURITY_CONTEXT_UUID,
					PermissionMode.WRITER).getTx();

			boolean removed = reallyRemoveFromContext();

			orientGraph.commit();
			logger.info(
					"{} with UUID {} successfully removed from actual Context",
					baseType, uuid);

			return removed;
		} catch (Exception e) {
			logger.error(
					"Unable to remove {} with UUID {} from actual Context",
					baseType, uuid, e);
			if (orientGraph != null) {
				orientGraph.rollback();
			}
			throw new ContextException(e);
		} finally {
			if (orientGraph != null) {
				orientGraph.shutdown();
			}
		}
	}

}