eagle-core/eagle-query/eagle-entity-base/src/main/java/org/apache/eagle/log/entity/GenericServiceAPIResponseEntityDeserializer.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.eagle.log.entity;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.ObjectCodec;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.type.TypeFactory;
import com.google.common.base.Preconditions;

import java.io.IOException;
import java.util.*;

/**
 * @since 3/18/15.
 */
public class GenericServiceAPIResponseEntityDeserializer
    extends JsonDeserializer<GenericServiceAPIResponseEntity> {
    private static final String META_FIELD = "meta";
    private static final String SUCCESS_FIELD = "success";
    private static final String EXCEPTION_FIELD = "exception";
    private static final String OBJ_FIELD = "obj";
    private static final String TYPE_FIELD = "type";

    @Override
    public GenericServiceAPIResponseEntity deserialize(JsonParser jp, DeserializationContext ctxt)
        throws IOException, JsonProcessingException {
        GenericServiceAPIResponseEntity entity = new GenericServiceAPIResponseEntity();
        ObjectCodec objectCodec = jp.getCodec();

        JsonNode rootNode = jp.getCodec().readTree(jp);
        if (rootNode.isObject()) {
            Iterator<Map.Entry<String, JsonNode>> fields = rootNode.fields();
            JsonNode objNode = null;
            while (fields.hasNext()) {
                Map.Entry<String, JsonNode> field = fields.next();
                if (META_FIELD.equals(field.getKey()) && field.getValue() != null) {
                    entity.setMeta(objectCodec.readValue(field.getValue().traverse(), Map.class));
                } else if (SUCCESS_FIELD.equals(field.getKey()) && field.getValue() != null) {
                    entity.setSuccess(field.getValue().booleanValue());
                } else if (EXCEPTION_FIELD.equals(field.getKey()) && field.getValue() != null) {
                    entity.setException(new Exception(field.getValue().textValue()));
                } else if (TYPE_FIELD.endsWith(field.getKey()) && field.getValue() != null) {
                    Preconditions.checkNotNull(field.getValue().textValue(), "Response type class is null");
                    try {
                        entity.setType(Class.forName(field.getValue().textValue()));
                    } catch (ClassNotFoundException e) {
                        throw new IOException(e);
                    }
                } else if (OBJ_FIELD.equals(field.getKey()) && field.getValue() != null) {
                    objNode = field.getValue();
                }
            }

            if (objNode != null) {
                JavaType collectionType = null;
                if (entity.getType() != null) {
                    collectionType = TypeFactory.defaultInstance().constructCollectionType(LinkedList.class,
                                                                                           entity.getType());
                } else {
                    collectionType = TypeFactory.defaultInstance().constructCollectionType(LinkedList.class,
                                                                                           Map.class);
                }
                List obj = objectCodec.readValue(objNode.traverse(), collectionType);
                entity.setObj(obj);
            }
        } else {
            throw new IOException("root node is not object");
        }
        return entity;
    }
}