/*

  * #%L

  * SingleDocumentCallback.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 com.allanbank.mongodb.Callback;

 import com.allanbank.mongodb.MongoDbException;

 import com.allanbank.mongodb.bson.Document;

 import com.allanbank.mongodb.client.MongoIteratorImpl;

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

 /**

  * Callback to convert a {@link Reply} into a single document.

  * 

  * @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 final class SingleDocumentCallback extends

         AbstractReplyCallback<Document> {

     /**

      * Create a new CursorCallback.

      * 

      * @param results

      *            The callback to update once the first set of results are

      *            ready.

      */

     public SingleDocumentCallback(final Callback<Document> results) {

         super(results);

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to construct a {@link MongoIteratorImpl} around the reply.

      * </p>

      * 

      * @see AbstractReplyCallback#convert(Reply)

      */

     @Override

     protected Document convert(final Reply reply) throws MongoDbException {

         if (!reply.getResults().isEmpty()) {

             return reply.getResults().get(0);

         }

         return null;

     }

 }