/*

  * #%L

  * ReplyResultCallback.java - mongodb-async-driver - Allanbank Consulting, Inc.

  * %%

  * Copyright (C) 2011 - 2014 Allanbank Consulting, Inc.

  * %%

  * 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.

  * #L%

  */

 package com.allanbank.mongodb.client.callback;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.List;

 import com.allanbank.mongodb.Callback;

 import com.allanbank.mongodb.MongoDbException;

 import com.allanbank.mongodb.MongoIterator;

 import com.allanbank.mongodb.bson.Document;

 import com.allanbank.mongodb.bson.element.DocumentElement;

 import com.allanbank.mongodb.client.SimpleMongoIteratorImpl;

 import com.allanbank.mongodb.client.message.Reply;

 /**

  * Callback to extract the map/reduce and aggregation results from the reply.

  * 

  * @api.no This class is <b>NOT</b> part of the drivers API. This class may be

  *         mutated in incompatible ways between any two releases of the driver.

  * @copyright 2011-2013, Allanbank Consulting, Inc., All Rights Reserved

  */

 public class ReplyResultCallback extends

         AbstractReplyCallback<MongoIterator<Document>> {

     /** The field in the reply holding the results. */

     private final String myReplyField;

     /**

      * Create a new ReplyResultCallback.

      * 

      * @param forwardCallback

      *            The callback to forward the result documents to.

      */

     public ReplyResultCallback(

             final Callback<MongoIterator<Document>> forwardCallback) {

         this("results", forwardCallback);

     }

     /**

      * Create a new ReplyResultCallback.

      * 

      * @param field

      *            The field in the reply holding the results.

      * @param forwardCallback

      *            The callback to forward the result documents to.

      */

     public ReplyResultCallback(final String field,

             final Callback<MongoIterator<Document>> forwardCallback) {

         super(forwardCallback);

         myReplyField = field;

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to extract the 'results' elements from the reply.

      * </p>

      * 

      * @see com.allanbank.mongodb.client.callback.AbstractReplyCallback#convert(com.allanbank.mongodb.client.message.Reply)

      */

     @Override

     protected MongoIterator<Document> convert(final Reply reply)

             throws MongoDbException {

         List<Document> results = Collections.emptyList();

         final List<Document> replyDocs = reply.getResults();

         if (replyDocs.size() == 1) {

             final Document doc = replyDocs.get(0);

             final List<DocumentElement> resultsElems = doc.find(

                     DocumentElement.class, myReplyField, ".*");

             if (!resultsElems.isEmpty()) {

                 results = new ArrayList<Document>();

                 for (final DocumentElement resultElem : resultsElems) {

                     results.add(resultElem.getDocument());

                 }

             }

         }

         return new SimpleMongoIteratorImpl<Document>(results);

     }

 }