/**
 * ============LICENSE_START=======================================================
 * Gizmo
 * ================================================================================
 * Copyright © 2017 AT&T Intellectual Property.
 * Copyright © 2017 Amdocs
 * All rights reserved.
 * ================================================================================
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * ============LICENSE_END=========================================================
 *
 * ECOMP is a trademark and service mark of AT&T Intellectual Property.
 */
package org.onap.crud.dao.champ;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import org.onap.aai.champcore.ChampGraph;
import org.onap.aai.champcore.ChampTransaction;
import org.onap.aai.champcore.exceptions.ChampMarshallingException;
import org.onap.aai.champcore.exceptions.ChampObjectNotExistsException;
import org.onap.aai.champcore.exceptions.ChampRelationshipNotExistsException;
import org.onap.aai.champcore.exceptions.ChampSchemaViolationException;
import org.onap.aai.champcore.exceptions.ChampTransactionException;
import org.onap.aai.champcore.exceptions.ChampUnmarshallingException;
import org.onap.aai.champcore.model.ChampObject;
import org.onap.aai.champcore.model.ChampRelationship;
import org.onap.aai.champcore.model.fluent.object.ObjectBuildOrPropertiesStep;
import org.onap.aai.cl.api.Logger;
import org.onap.aai.cl.eelf.LoggerFactory;
import org.onap.crud.dao.GraphDao;
import org.onap.crud.entity.Edge;
import org.onap.crud.entity.Vertex;
import org.onap.crud.exception.CrudException;
import org.onap.crud.logging.CrudServiceMsgs;

/**
 * This is the integration layer between the CRUD API service and the low level
 * Champ library for graph database interaction.
 */
public class ChampDao implements GraphDao {

  public static final String CONFIG_STORAGE_BACKEND = "storage.backend";
  public static final String CONFIG_STORAGE_BACKEND_DB = "storage.backend.db";
  public static final String STORAGE_HBASE_DB = "hbase";
  public static final String STORAGE_CASSANDRA_DB = "cassandra";
  public static final String CONFIG_STORAGE_HOSTNAMES = "storage.hostnames";
  public static final String CONFIG_STORAGE_PORT = "storage.port";
  public static final String CONFIG_HBASE_ZNODE_PARENT = "storage.hbase.ext.zookeeper.znode.parent";
  public static final String CONFIG_GRAPH_NAME = "graph.name";
  public static final String GRAPH_UNQ_INSTANCE_ID_SUFFIX = "graph.unique-instance-id-suffix";

  public static final String CONFIG_EVENT_STREAM_PUBLISHER = "event.stream.publisher";
  public static final String CONFIG_EVENT_STREAM_NUM_PUBLISHERS = "event.stream.num-publishers";

  private static Map<String, ChampTransaction> transactions = new ConcurrentHashMap<String, ChampTransaction>();
  public static final String DEFAULT_GRAPH_NAME = "default_graph";

  private enum GraphType {
    IN_MEMORY, TITAN, DSE
  }

  /**
   * Instance of the API used for interacting with the Champ library.
   */
  private ChampGraph champApi = null;

  private Logger logger = LoggerFactory.getInstance().getLogger(ChampDao.class.getName());

  /**
   * Creates a new instance of the ChampDao.
   *
   * @param champGraph
   *          - Concrete implementation of the graph dao layer
   */
  public ChampDao(ChampGraph champGraph) {
    this.champApi = champGraph;
  }

  @Override
  public Vertex getVertex(String id) throws CrudException {

    try {

      if (logger.isDebugEnabled()) {
        logger.debug("getVertex with id: " + id);
      }

      long idAsLong = Long.parseLong(id);

      Optional<ChampObject> retrievedVertex = champApi.retrieveObject(idAsLong);

      String nodeType = org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName();
      if (retrievedVertex.isPresent() && retrievedVertex.get().getProperties().get(nodeType) != null) {
        return vertexFromChampObject(retrievedVertex.get(),
            retrievedVertex.get().getProperties().get(nodeType).toString());
      } else {

        // We didn't find a vertex with the supplied id, so just throw an
        // exception.
        throw new CrudException("No vertex with id " + id + " found in graph",
            javax.ws.rs.core.Response.Status.NOT_FOUND);
      }

    } catch (ChampUnmarshallingException | ChampTransactionException e) {

      // Something went wrong - throw an exception.
      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public Vertex getVertex(String id, String type) throws CrudException {

    try {

      if (logger.isDebugEnabled()) {
        logger.debug("getVertex with id: " + id);
      }

      long idAsLong = Long.parseLong(id);

      // Request the vertex from the graph db.
      Optional<ChampObject> retrievedVertex = champApi.retrieveObject(idAsLong);

      // Did we find it?
      if (retrievedVertex.isPresent()
          && retrievedVertex.get().getProperties()
              .get(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName()) != null
          && retrievedVertex.get().getProperties()
              .get(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName()).toString()
              .equalsIgnoreCase(type)) {

        // Yup, convert it to a Vector object and return it.
        return vertexFromChampObject(retrievedVertex.get(), type);

      } else {

        // We didn't find a vertex with the supplied id, so just throw an
        // exception.
        throw new CrudException("No vertex with id " + id + " found in graph",
            javax.ws.rs.core.Response.Status.NOT_FOUND);
      }

    } catch (ChampUnmarshallingException | ChampTransactionException e) {

      // Something went wrong - throw an exception.
      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public List<Edge> getVertexEdges(String id) throws CrudException {

    if (logger.isDebugEnabled()) {
      logger.debug("get Edges incident to vertex with id: " + id + " from graph");
    }

    try {
      long idAsLong = Long.parseLong(id); // GDF - what to do about id???

      // Request the vertex from the graph db.
      Optional<ChampObject> retrievedVertex = champApi.retrieveObject(idAsLong);

      // Did we find it?
      if (retrievedVertex.isPresent()) {

        // Query the Champ library for the edges which are incident to the
        // specified
        // vertex.
        Stream<ChampRelationship> relationships = champApi.retrieveRelationships(retrievedVertex.get());

        // Build an edge list from the result stream.
        List<Edge> edges = new ArrayList<Edge>();
        relationships.forEach(r -> edges.add(edgeFromChampRelationship(r)));

        return edges;

      } else {

        // We couldn't find the specified vertex, so throw an exception.
        throw new CrudException("No vertex with id " + id + " found in graph",
            javax.ws.rs.core.Response.Status.NOT_FOUND);
      }

    } catch (ChampUnmarshallingException e) {

      // Something went wrong, so throw an exception.
      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);

    } catch (ChampObjectNotExistsException e) {

      // We couldn't find the specified vertex, so throw an exception.
      throw new CrudException("No vertex with id " + id + " found in graph",
          javax.ws.rs.core.Response.Status.NOT_FOUND);
    } catch (ChampTransactionException e) {
      throw new CrudException("Transaction error occured", javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public Vertex addVertex(String type, Map<String, Object> properties) throws CrudException {

    if (logger.isDebugEnabled()) {
      logger.debug("Add/update vertex: {label: " + type + " properties:" + propertiesMapToString(properties));
    }

    // Add the aai_node_type so that AAI can read the data created by gizmo
    properties.put(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName(), type);

    // Create an object to represent our vertex in the format expected by the
    // Champ library.
    ChampObject objectToCreate = buildChampObject(type, properties);

    try {

      // Ask the Champ library to store our vertex, placing the returned object
      // into a
      // list so that we can easily put that into our result object.
      return vertexFromChampObject(champApi.storeObject(objectToCreate), type);

    } catch (ChampMarshallingException | ChampSchemaViolationException | ChampObjectNotExistsException
        | ChampTransactionException e) {

      // Something went wrong - throw an exception.
      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public Vertex updateVertex(String id, String type, Map<String, Object> properties) throws CrudException {

    if (logger.isDebugEnabled()) {
      logger.debug("Update vertex with id: " + id + " with properties: " + propertiesMapToString(properties));
    }
    // Add the aai_node_type so that AAI can read the data created by gizmo
    properties.put(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName(), type);

    try {
      // Now, build the updated version of the Champ Object...
      ChampObject updateObject = buildChampObject(id, type, properties);
      // ...and send it to the Champ library.
      return vertexFromChampObject(champApi.replaceObject(updateObject), type);

    } catch (ChampObjectNotExistsException e) {
      throw new CrudException("Not Found", javax.ws.rs.core.Response.Status.NOT_FOUND);
    } catch (NumberFormatException | ChampMarshallingException | ChampSchemaViolationException e) {
      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    } catch (ChampTransactionException e) {
      throw new CrudException("Transaction error occured", javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }

  }

  @Override
  public List<Vertex> getVertices(String type, Map<String, Object> filter) throws CrudException {

    if (logger.isDebugEnabled()) {
      logger.debug("Retrieve vertices with type label: " + type + " which map query parameters: "
          + propertiesMapToString(filter));
    }

    filter.put(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName(), type);

    Stream<ChampObject> retrievedVertices;
    try {
      retrievedVertices = champApi.queryObjects(filter);

    } catch (ChampTransactionException e) {
      throw new CrudException("Transaction error occured", javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }

    List<Vertex> vertices = retrievedVertices.map(v -> vertexFromChampObject(v, type)).collect(Collectors.toList());

    if (logger.isDebugEnabled()) {
      logger.debug("Resulting vertex list: " + retrievedVertices);
    }

    // ...and return it to the caller.
    return vertices;
  }

  private Object getRelKey(String id) {
    Object key = id;
    // convert into Long if applicable . TODO : revisit in story NUC-304
    try {
      key = Long.parseLong(id);
    } catch (NumberFormatException e) {
      // The id isn't a Long, leave it as a string
    }

    return key;
  }

  @Override
  public Edge getEdge(String id, String type) throws CrudException {

    if (logger.isDebugEnabled()) {
      logger.debug("Get edge with id: " + id);
    }

    try {

      // Request the edge from the graph db.
      Optional<ChampRelationship> relationship = champApi.retrieveRelationship(getRelKey(id));

      // Did we find it?
      if (relationship.isPresent() && relationship.get().getType().equals(type)) {

        // Yup - return the result.
        return edgeFromChampRelationship(relationship.get());

      } else {

        // We didn't find an edge with the supplied id, so throw an exception.
        throw new CrudException("No edge with id " + id + " found in graph",
            javax.ws.rs.core.Response.Status.NOT_FOUND);
      }

    } catch (ChampUnmarshallingException | ChampTransactionException e) {

      // Something went wrong, so throw an exception.
      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public Edge addEdge(String type, Vertex source, Vertex target, Map<String, Object> properties) throws CrudException {

    // For now, assume source and target are straight ids...
    try {

      Optional<ChampObject> sourceObject = champApi.retrieveObject(Long.parseLong(source.getId().get()));
      if (!sourceObject.isPresent() || !sourceObject.get().getType().equals(source.getType())) {
        throw new CrudException(
            "Error creating edge - source vertex with id " + source + " does not exist in graph data base",
            javax.ws.rs.core.Response.Status.BAD_REQUEST);
      }

      Optional<ChampObject> targetObject = champApi.retrieveObject(Long.parseLong(target.getId().get()));
      if (!targetObject.isPresent() || !targetObject.get().getType().equals(target.getType())) {
        throw new CrudException(
            "Error creating edge - target vertex with id " + target + " does not exist in graph data base",
            javax.ws.rs.core.Response.Status.BAD_REQUEST);
      }

      // Now, create the ChampRelationship object for our edge and store it in
      // the graph database.
      return edgeFromChampRelationship(champApi.storeRelationship(
          new ChampRelationship.Builder(sourceObject.get(), targetObject.get(), type).properties(properties).build()));

    } catch (ChampMarshallingException | ChampObjectNotExistsException | ChampSchemaViolationException
        | ChampRelationshipNotExistsException | ChampUnmarshallingException | NumberFormatException
        | ChampTransactionException e) {

      throw new CrudException("Error creating edge: " + e.getMessage(),
          javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public List<Edge> getEdges(String type, Map<String, Object> filter) throws CrudException {

    filter.put(ChampRelationship.ReservedPropertyKeys.CHAMP_RELATIONSHIP_TYPE.toString(), type);

    Stream<ChampRelationship> retrievedRelationships;
    try {
      retrievedRelationships = champApi.queryRelationships(filter);

    } catch (ChampTransactionException e) {
      throw new CrudException("Transaction error occured", javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }

    // Process the result stream from the Champ library into an Edge list,
    // keeping only
    // edges of the specified type.
    List<Edge> edges = retrievedRelationships.map(r -> edgeFromChampRelationship(r)).collect(Collectors.toList());

    return edges;
  }

  @Override
  public Edge updateEdge(Edge edge) throws CrudException {

    if (logger.isDebugEnabled()) {
      logger.debug(
          "Update edge with id: " + edge.getId() + " with properties: " + propertiesMapToString(edge.getProperties()));
    }

    try {
      // Now, build the updated version of the Champ Relationship...
      ChampRelationship updateRelationship = new ChampRelationship.Builder(
          buildChampObject(edge.getSource().getId().get(), edge.getSource().getType(),
              edge.getSource().getProperties()),
          buildChampObject(edge.getTarget().getId().get(), edge.getTarget().getType(),
              edge.getTarget().getProperties()),
          edge.getType()).key(getRelKey(edge.getId().get())).properties(edge.getProperties()).build();
      // ...and send it to the Champ library.
      return edgeFromChampRelationship(champApi.replaceRelationship(updateRelationship));

    } catch (ChampRelationshipNotExistsException ex) {
      throw new CrudException("Not Found", javax.ws.rs.core.Response.Status.NOT_FOUND);
    } catch (NumberFormatException | ChampUnmarshallingException | ChampMarshallingException
        | ChampSchemaViolationException | ChampTransactionException ex) {

      throw new CrudException(ex.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public void deleteVertex(String id, String type) throws CrudException {

    try {

      // First, retrieve the vertex that we intend to delete.
      Optional<ChampObject> retrievedVertex = champApi.retrieveObject(Long.parseLong(id));

      // Did we find it?
      if (!retrievedVertex.isPresent() || !retrievedVertex.get().getType().equals(type)) {
        throw new CrudException("Failed to delete vertex with id: " + id + " - vertex does not exist.",
            javax.ws.rs.core.Response.Status.NOT_FOUND);
      }

      // Now, verify that there are no edges incident to the vertex (they must
      // be deleted
      // first if so).
      Stream<ChampRelationship> relationships = champApi.retrieveRelationships(retrievedVertex.get());

      if (relationships.count() > 0) {
        throw new CrudException("Attempt to delete vertex with id " + id + " which has incident edges.",
            javax.ws.rs.core.Response.Status.BAD_REQUEST);
      }

      // Finally, we can attempt to delete our vertex.
      champApi.deleteObject(Long.parseLong(id));

    } catch (NumberFormatException | ChampUnmarshallingException | ChampObjectNotExistsException
        | ChampTransactionException e) {

      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public void deleteEdge(String id, String type) throws CrudException {

    try {

      // First, retrieve the edge that we want to delete.
      Optional<ChampRelationship> relationshipToDelete = champApi.retrieveRelationship(getRelKey(id));

      // Did we find it?
      if (!relationshipToDelete.isPresent() || !relationshipToDelete.get().getType().equals(type)) {
        throw new CrudException("Failed to delete edge with id: " + id + " - edge does not exist",
            javax.ws.rs.core.Response.Status.NOT_FOUND);
      }

      // Now we can delete the edge.
      champApi.deleteRelationship(relationshipToDelete.get());

    } catch (ChampRelationshipNotExistsException | NumberFormatException | ChampUnmarshallingException
        | ChampTransactionException e) {

      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  /**
   * This helper method generates a string representation of a properties map
   * for logging purposes.
   *
   * @param properties
   *          - The properties map to be converted.
   * @return - The log statement friendly conversion of the properties map.
   */
  private String propertiesMapToString(Map<String, Object> properties) {

    StringBuilder sb = new StringBuilder();
    sb.append("{");

    for (String key : properties.keySet()) {
      sb.append("(").append(key).append(" -> ").append(properties.get(key)).append(") ");
    }

    sb.append("}");

    return sb.toString();
  }

  /**
   * This helper method constructs a {@link ChampObject} suitable for passing to
   * the Champ library.
   *
   * @param type
   *          - The type to assign to our ChampObject
   * @param properties
   *          - The set of properties to assign to our ChampObject
   * @return - A populated ChampObject
   */
  private ChampObject buildChampObject(String type, Map<String, Object> properties) {

    ObjectBuildOrPropertiesStep objectInProgress = ChampObject.create().ofType(type).withoutKey();

    for (String key : properties.keySet()) {
      objectInProgress.withProperty(key, properties.get(key));
    }
    return objectInProgress.build();
  }

  /**
   * This helper method constructs a {@link ChampObject} suitable for passing to
   * the Champ library.
   *
   * @param id
   *          - Unique identifier for this object.
   * @param type
   *          - The type to assign to our ChampObject
   * @param properties
   *          - The set of properties to assign to our ChampObject
   * @return - A populated ChampObject
   */
  private ChampObject buildChampObject(String id, String type, Map<String, Object> properties) {

    ObjectBuildOrPropertiesStep objectInProgress = ChampObject.create().ofType(type).withKey(Long.parseLong(id));

    for (String key : properties.keySet()) {
      objectInProgress.withProperty(key, properties.get(key));
    }
    return objectInProgress.build();
  }

  private Vertex vertexFromChampObject(ChampObject champObject, String type) {

    // Get the identifier for this vertex from the Champ object.
    Object id = champObject.getKey().orElse("");

    // Start building our {@link Vertex} object.
    Vertex.Builder vertexBuilder = new Vertex.Builder(type);
    vertexBuilder.id(id.toString());

    // Convert the properties associated with the Champ object into the form
    // expected for
    // a Vertex object.
    for (String key : champObject.getProperties().keySet()) {
      vertexBuilder.property(key, champObject.getProperties().get(key));
    }

    // ...and return it.
    return vertexBuilder.build();
  }

  /**
   * This helper method converts a {@link ChampRelationship} from the Champ
   * library into an equivalent {@link Edge} object that is understood by the
   * CRUD Service.
   *
   * @param relationship
   *          - The ChampRelationship object to be converted.
   * @return - An Edge object corresponding to the supplied ChampRelationship
   */
  private Edge edgeFromChampRelationship(ChampRelationship relationship) {

    // Populate the edge's id, if available.
    Object relationshipId = relationship.getKey().orElse("");

    Edge.Builder edgeBuilder = new Edge.Builder(relationship.getType()).id(relationshipId.toString());
    edgeBuilder.source(vertexFromChampObject(relationship.getSource(),
        relationship.getSource().getProperties()
            .get(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName()) == null
                ? relationship.getSource().getType()
                : relationship.getSource().getProperties()
                    .get(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName()).toString()));
    edgeBuilder.target(vertexFromChampObject(relationship.getTarget(),
        relationship.getTarget().getProperties()
            .get(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName()) == null
                ? relationship.getTarget().getType()
                : relationship.getTarget().getProperties()
                    .get(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName()).toString()));

    for (String key : relationship.getProperties().keySet()) {
      edgeBuilder.property(key, relationship.getProperties().get(key).toString());
    }

    return edgeBuilder.build();
  }

  /**
   * Performs any necessary shut down operations when the DAO is no longer
   * needed.
   */
  public void close() {

    if (champApi != null) {

      logger.info(CrudServiceMsgs.STOPPING_CHAMP_DAO);

      champApi.shutdown();
    }
  }

  @Override
  public String openTransaction() {

    ChampTransaction transaction = champApi.openTransaction();

    transactions.put(transaction.id(), transaction);
    logger.info(CrudServiceMsgs.TRANSACTION, "Stored transaction " + transaction.id() + " in hashmap");
    logger.info(CrudServiceMsgs.TRANSACTION, "Hash map contents:");
    for (String key : transactions.keySet()) {
      logger.info(CrudServiceMsgs.TRANSACTION, key);
    }
    return transaction.id();
  }

  @Override
  public void commitTransaction(String id) throws CrudException {

    try {
      champApi.commitTransaction(getTransaction(id));
    } catch (ChampTransactionException e) {
      throw new CrudException("Error while commiting transaction " + id,
          javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
    transactions.remove(id);
  }

  @Override
  public void rollbackTransaction(String id) throws CrudException {

    try {
      champApi.rollbackTransaction(getTransaction(id));
    } catch (ChampTransactionException e) {
      throw new CrudException("Error while transaction rollback " + id,
          javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
    transactions.remove(id);
  }

  private ChampTransaction getTransaction(String id) throws CrudException {

    logger.info(CrudServiceMsgs.TRANSACTION, "Looking up transaction " + id);
    if (transactions.containsKey(id)) {
      logger.info(CrudServiceMsgs.TRANSACTION, "Found it!");
      return (transactions.get(id));
    } else {
      logger.info(CrudServiceMsgs.TRANSACTION, "Didn't find transaction id " + id + ".  Hash map contains: ");
      for (String key : transactions.keySet()) {
        logger.info(CrudServiceMsgs.TRANSACTION, key);
      }
      throw new CrudException("No open transaction with id: " + id, javax.ws.rs.core.Response.Status.NOT_FOUND);
    }
  }

  @Override
  public Vertex addVertex(String type, Map<String, Object> properties, String txId) throws CrudException {
    if (logger.isDebugEnabled()) {
      logger.debug("Add/update vertex: {label: " + type + " properties:" + propertiesMapToString(properties));
    }

    // Add the aai_node_type so that AAI can read the data created by gizmo
    properties.put(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName(), type);

    // Create an object to represent our vertex in the format expected by the
    // Champ library.
    ChampObject objectToCreate = buildChampObject(type, properties);

    try {

      // Ask the Champ library to store our vertex, placing the returned object
      // into a
      // list so that we can easily put that into our result object.
      return vertexFromChampObject(champApi.storeObject(objectToCreate, Optional.of(getTransaction(txId))), type);

    } catch (ChampMarshallingException | ChampSchemaViolationException | ChampObjectNotExistsException
        | ChampTransactionException e) {

      // Something went wrong - throw an exception.
      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public Edge addEdge(String type, Vertex source, Vertex target, Map<String, Object> properties, String txId)
      throws CrudException {
    // For now, assume source and target are straight ids...
    try {

      Optional<ChampObject> sourceObject = champApi.retrieveObject(Long.parseLong(source.getId().get()),
          Optional.of(getTransaction(txId)));
      if (!sourceObject.isPresent() || !sourceObject.get().getType().equals(source.getType())) {
        throw new CrudException(
            "Error creating edge - source vertex with id " + source + " does not exist in graph data base",
            javax.ws.rs.core.Response.Status.BAD_REQUEST);
      }

      Optional<ChampObject> targetObject = champApi.retrieveObject(Long.parseLong(target.getId().get()),
          Optional.of(getTransaction(txId)));
      if (!targetObject.isPresent() || !targetObject.get().getType().equals(target.getType())) {
        throw new CrudException(
            "Error creating edge - target vertex with id " + target + " does not exist in graph data base",
            javax.ws.rs.core.Response.Status.BAD_REQUEST);
      }

      // Now, create the ChampRelationship object for our edge and store it in
      // the graph database.
      return edgeFromChampRelationship(champApi.storeRelationship(
          new ChampRelationship.Builder(sourceObject.get(), targetObject.get(), type).properties(properties).build(),
          Optional.of(getTransaction(txId))));

    } catch (ChampMarshallingException | ChampObjectNotExistsException | ChampSchemaViolationException
        | ChampTransactionException | ChampRelationshipNotExistsException | ChampUnmarshallingException e) {

      throw new CrudException("Error creating edge: " + e.getMessage(),
          javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }

  }

  @Override
  public Vertex updateVertex(String id, String type, Map<String, Object> properties, String txId) throws CrudException {
    if (logger.isDebugEnabled()) {
      logger.debug("Update vertex with id: " + id + " with properties: " + propertiesMapToString(properties));
    }
    // Add the aai_node_type so that AAI can read the data created by gizmo
    properties.put(org.onap.schema.OxmModelValidator.Metadata.NODE_TYPE.propertyName(), type);

    try {
      // Now, build the updated version of the Champ Object...
      ChampObject updateObject = buildChampObject(id, type, properties);
      // ...and send it to the Champ library.
      return vertexFromChampObject(champApi.replaceObject(updateObject, Optional.of(getTransaction(txId))), type);

    } catch (ChampObjectNotExistsException e) {
      throw new CrudException("Not Found", javax.ws.rs.core.Response.Status.NOT_FOUND);
    } catch (NumberFormatException | ChampMarshallingException | ChampTransactionException
        | ChampSchemaViolationException e) {
      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public boolean transactionExists(String id) throws CrudException {
    return transactions.containsKey(id);
  }

  @Override
  public void deleteVertex(String id, String type, String txId) throws CrudException {
    try {

      // First, retrieve the vertex that we intend to delete.
      Optional<ChampObject> retrievedVertex = champApi.retrieveObject(Long.parseLong(id),
          Optional.of(getTransaction(txId)));

      // Did we find it?
      if (!retrievedVertex.isPresent() || !retrievedVertex.get().getType().equals(type)) {
        throw new CrudException("Failed to delete vertex with id: " + id + " - vertex does not exist.",
            javax.ws.rs.core.Response.Status.NOT_FOUND);
      }

      // Now, verify that there are no edges incident to the vertex (they must
      // be deleted
      // first if so).
      Stream<ChampRelationship> relationships = champApi.retrieveRelationships(retrievedVertex.get(),
          Optional.of(getTransaction(txId)));

      if (relationships.count() > 0) {
        throw new CrudException("Attempt to delete vertex with id " + id + " which has incident edges.",
            javax.ws.rs.core.Response.Status.BAD_REQUEST);
      }

      // Finally, we can attempt to delete our vertex.
      champApi.deleteObject(Long.parseLong(id), Optional.of(getTransaction(txId)));

    } catch (NumberFormatException | ChampUnmarshallingException | ChampObjectNotExistsException
        | ChampTransactionException e) {

      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }

  }

  @Override
  public Edge updateEdge(Edge edge, String txId) throws CrudException {
    if (logger.isDebugEnabled()) {
      logger.debug(
          "Update edge with id: " + edge.getId() + " with properties: " + propertiesMapToString(edge.getProperties()));
    }

    try {
      // Now, build the updated version of the Champ Relationship...
      ChampRelationship updateRelationship = new ChampRelationship.Builder(
          buildChampObject(edge.getSource().getId().get(), edge.getSource().getType(),
              edge.getSource().getProperties()),
          buildChampObject(edge.getTarget().getId().get(), edge.getTarget().getType(),
              edge.getTarget().getProperties()),
          edge.getType()).key(getRelKey(edge.getId().get())).properties(edge.getProperties()).build();
      // ...and send it to the Champ library.
      return edgeFromChampRelationship(
          champApi.replaceRelationship(updateRelationship, Optional.of(getTransaction(txId))));

    } catch (ChampRelationshipNotExistsException ex) {
      throw new CrudException("Not Found", javax.ws.rs.core.Response.Status.NOT_FOUND);
    } catch (NumberFormatException | ChampUnmarshallingException | ChampMarshallingException
        | ChampSchemaViolationException | ChampTransactionException ex) {

      throw new CrudException(ex.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

  @Override
  public void deleteEdge(String id, String type, String txId) throws CrudException {
    try {

      // First, retrieve the edge that we want to delete.
      Optional<ChampRelationship> relationshipToDelete = champApi.retrieveRelationship(getRelKey(id),
          Optional.of(getTransaction(txId)));

      // Did we find it?
      if (!relationshipToDelete.isPresent() || !relationshipToDelete.get().getType().equals(type)) {
        throw new CrudException("Failed to delete edge with id: " + id + " - edge does not exist",
            javax.ws.rs.core.Response.Status.NOT_FOUND);
      }

      // Now we can delete the edge.
      champApi.deleteRelationship(relationshipToDelete.get(), Optional.of(getTransaction(txId)));

    } catch (ChampRelationshipNotExistsException | NumberFormatException | ChampUnmarshallingException
        | ChampTransactionException e) {

      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }

  }

  @Override
  public Edge getEdge(String id, String type, String txId) throws CrudException {
    if (logger.isDebugEnabled()) {
      logger.debug("Get edge with id: " + id);
    }

    try {

      // Request the edge from the graph db.
      Optional<ChampRelationship> relationship = champApi.retrieveRelationship(getRelKey(id),
          Optional.of(getTransaction(txId)));

      // Did we find it?
      if (relationship.isPresent() && relationship.get().getType().equals(type)) {

        // Yup - return the result.
        return edgeFromChampRelationship(relationship.get());

      } else {

        // We didn't find an edge with the supplied id, so throw an exception.
        throw new CrudException("No edge with id " + id + " found in graph",
            javax.ws.rs.core.Response.Status.NOT_FOUND);
      }

    } catch (ChampUnmarshallingException | ChampTransactionException e) {

      // Something went wrong, so throw an exception.
      throw new CrudException(e.getMessage(), javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR);
    }
  }

}