RelationshipEmbeddedJacksonSerializer.java

/*
 * Copyright 2015-2016 Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags.
 *
 * 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.
 */
package org.hawkular.inventory.rest.json;

import java.io.IOException;
import java.util.Map;

import org.hawkular.inventory.api.model.Relationship;
import org.hawkular.inventory.paths.CanonicalPath;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;

/**
 * @author Jirka Kremser
 * @since 0.1.0
 */
public class RelationshipEmbeddedJacksonSerializer extends JsonSerializer<Relationship> {
    public static final String FIELD_CONTEXT_KEY = "@context";
    public static final String FIELD_CONTEXT_URI = "http://hawkular.org/inventory/0.1.0/relationship.jsonld";
    public static final String FIELD_ID = RelationshipJacksonSerializer.FIELD_ID;
    public static final String FIELD_SHORT_ID = "shortId";
    public static final String FIELD_NAME = RelationshipJacksonSerializer.FIELD_NAME;
    public static final String FIELD_SOURCE = RelationshipJacksonSerializer.FIELD_SOURCE;
    public static final String FIELD_TARGET = RelationshipJacksonSerializer.FIELD_TARGET;
    public static final String FIELD_TYPE = "type";
    public static final String FIELD_PROPERTIES = RelationshipJacksonSerializer.FIELD_PROPERTIES;

    /**
     * <pre>compact:
     * {
     *   "id": "1337",
     *   "source": "/tenants/28026b36-8fe4-4332-84c8-524e173a68bf",
     *   "name": "contains",
     *   "target": "28026b36-8fe4-4332-84c8-524e173a68bf/environments/test"
     * }</pre>
     * <p>
     * <pre>embedded:
     * {
     *   "@context": "http://hawkular.org/inventory/0.1.0/relationship.jsonld",
     *   "id": "1337",
     *   "name": "contains",
     *   "source": {
     *      id: "/tenants/28026b36-8fe4-4332-84c8-524e173a68bf",
     *      shortId: "28026b36-8fe4-4332-84c8-524e173a68bf",
     *      type: "Tenant"
     *   },
     *   "target": {
     *      id: "28026b36-8fe4-4332-84c8-524e173a68bf/environments/test",
     *      shortId: "test",
     *      type: "Environment"
     *   }
     * }</pre>
     */
    @Override
    public void serialize(Relationship relationship, JsonGenerator jg, SerializerProvider
            serializerProvider) throws IOException {
        jg.writeStartObject();

        jg.writeFieldName(FIELD_CONTEXT_KEY);
        jg.writeString(FIELD_CONTEXT_URI);

        jg.writeFieldName(FIELD_ID);
        jg.writeString(relationship.getId());

        jg.writeFieldName(FIELD_NAME);
        jg.writeString(relationship.getName());

        serializeEntity(relationship.getSource(), jg, FIELD_SOURCE);
        serializeEntity(relationship.getTarget(), jg, FIELD_TARGET);

        if (relationship.getProperties() != null && !relationship.getProperties().isEmpty()) {
            jg.writeFieldName(FIELD_PROPERTIES);
            jg.writeStartObject();
            for (Map.Entry<String, Object> property : relationship.getProperties().entrySet()) {
                jg.writeFieldName(property.getKey());
                jg.writeObject(property.getValue());
            }
            jg.writeEndObject();
        }

        jg.writeEndObject();
    }

    private void serializeEntity(CanonicalPath entity, JsonGenerator jsonGenerator, String fieldName)
            throws IOException {
        jsonGenerator.writeFieldName(fieldName);
        jsonGenerator.writeStartObject();

        jsonGenerator.writeFieldName(FIELD_ID);
        jsonGenerator.writeString(entity.getPath().toString());

        jsonGenerator.writeFieldName(FIELD_SHORT_ID);
        jsonGenerator.writeString(entity.getSegment().getElementId());

        jsonGenerator.writeFieldName(FIELD_TYPE);
        jsonGenerator.writeString(entity.getSegment().getElementType().getSimpleName());

        jsonGenerator.writeEndObject();
    }
}