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A driver for DataStax Enterprise (DSE) and Apache Cassandra 1.2+ clusters that works exclusively with the Cassandra Query Language version 3 (CQL3) and Cassandra's binary protocol, supporting DSE-specific features such as geospatial types, DSE Graph and DSE authentication.

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/*
 * Copyright DataStax, Inc.
 *
 * This software can be used solely with DataStax Enterprise. Please consult the license at
 * http://www.datastax.com/terms/datastax-dse-driver-license-terms
 */
package com.datastax.driver.dse.graph;

import static com.fasterxml.jackson.core.JsonToken.END_ARRAY;
import static com.fasterxml.jackson.core.JsonToken.END_OBJECT;
import static com.fasterxml.jackson.core.JsonToken.FIELD_NAME;
import static com.fasterxml.jackson.core.JsonToken.START_ARRAY;
import static com.fasterxml.jackson.core.JsonToken.START_OBJECT;
import static com.fasterxml.jackson.core.JsonToken.VALUE_STRING;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
import com.google.common.collect.MultimapBuilder;
import java.io.IOException;

class DefaultVertexDeserializer extends StdDeserializer {

  DefaultVertexDeserializer() {
    super(DefaultVertex.class);
  }

  @Override
  public DefaultVertex deserialize(JsonParser parser, DeserializationContext ctx)
      throws IOException {
    assert parser.getCurrentToken() == START_OBJECT;
    DefaultVertex vertex = new DefaultVertex();
    while (parser.nextToken() != END_OBJECT) {
      assert parser.getCurrentToken() == FIELD_NAME;
      String name = parser.getCurrentName();
      parser.nextToken();
      if ("id".equals(name)) {
        assert parser.getCurrentToken() == START_OBJECT;
        vertex = readId(vertex, parser);
      } else if ("label".equals(name)) {
        assert parser.getCurrentToken() == VALUE_STRING;
        vertex = readLabel(vertex, parser);
      } else if ("type".equals(name)) {
        assert parser.getCurrentToken() == VALUE_STRING;
        vertex = readType(vertex, parser);
      } else if ("properties".equals(name)) {
        assert parser.getCurrentToken() == START_OBJECT;
        while (parser.nextToken() != END_OBJECT) {
          assert parser.getCurrentToken() == FIELD_NAME;
          String key = parser.getCurrentName();
          parser.nextToken();
          vertex = readProperty(vertex, key, parser);
        }
      } else {
        parser.nextToken();
        parser.skipChildren();
      }
    }
    return vertex;
  }

  private DefaultVertex readId(DefaultVertex vertex, JsonParser parser) throws IOException {
    JsonNode jacksonNode = parser.readValueAsTree();
    vertex.id = new DefaultGraphNode(jacksonNode, (ObjectMapper) parser.getCodec());
    return vertex;
  }

  private DefaultVertex readLabel(DefaultVertex vertex, JsonParser parser) throws IOException {
    vertex.label = parser.readValueAs(String.class);
    return vertex;
  }

  private DefaultVertex readType(DefaultVertex vertex, JsonParser parser) throws IOException {
    String type = parser.readValueAs(String.class);
    if (type == null || !type.equals("vertex"))
      throw new JsonParseException(parser, String.format("Expected 'vertex' type, got '%s'", type));
    return vertex;
  }

  private DefaultVertex readProperty(DefaultVertex vertex, String propertyName, JsonParser parser)
      throws IOException {
    if (vertex.properties == null) {
      vertex.properties = MultimapBuilder.linkedHashKeys().linkedHashSetValues().build();
    }
    // vertex properties can be multivaluated
    assert parser.getCurrentToken() == START_ARRAY;
    while (parser.nextToken() != END_ARRAY) {
      assert parser.getCurrentToken() == START_OBJECT;
      JsonNode jacksonNode = parser.readValueAsTree();
      PropertyGraphNode propertyValue =
          new PropertyGraphNode(
              jacksonNode, (ObjectMapper) parser.getCodec(), propertyName, vertex);
      vertex.properties.put(propertyName, propertyValue);
    }
    return vertex;
  }
}