/*
    * #%L
    * CursorCallback.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.concurrent.atomic.AtomicBoolean;
  
  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.client.Client;
  import com.allanbank.mongodb.client.MongoIteratorImpl;
  import com.allanbank.mongodb.client.message.CursorableMessage;
  import com.allanbank.mongodb.client.message.Query;
  import com.allanbank.mongodb.client.message.Reply;
  
  /**
   * Callback to convert a {@link CursorableMessage} {@link Reply} into a
   * {@link MongoIteratorImpl}.
   * 
   * @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 CursorCallback extends
          AbstractReplyCallback<MongoIterator<Document>> implements AddressAware {
  
      /** The server the original request was sent to. */
      private volatile String myAddress;
  
      /** The original query. */
      private final Client myClient;
  
      /** If true then the callback should expect a command formated cursor reply. */
      private final boolean myCommand;
  
      /** The original message to start the cursor. */
      private final CursorableMessage myMessage;
  
      /** The reply to the query. */
      private volatile Reply myReply;
  
      /**
       * Initially set to false. Set to true for the first of address or reply
       * being set. The second fails and {@link #trigger() triggers} the callback.
       */
      private final AtomicBoolean mySetOther;
  
      /**
       * Create a new CursorCallback.
       * 
       * @param client
       *            The client interface to the server.
       * @param message
       *            The original query.
       * @param command
       *            If true then the callback should expect a command formated
       *            cursor reply.
       * @param results
       *            The callback to update once the first set of results are
       *            ready.
       */
      public CursorCallback(final Client client, final CursorableMessage message,
              final boolean command,
              final Callback<MongoIterator<Document>> results) {
  
          super(results);
  
          myClient = client;
          myMessage = message;
          myCommand = command;
  
          mySetOther = new AtomicBoolean(false);
      }
  
      /**
       * Returns the server the original request was sent to.
       * 
       * @return The server the original request was sent to.
       */
      public String getAddress() {
         return myAddress;
     }
 
     /**
      * Sets the value of the server the original request was sent to.
      * 
      * @param address
      *            The new value for the server the original request was sent to.
      */
     @Override
     public void setAddress(final String address) {
         myAddress = address;
         trigger();
     }
 
     /**
      * {@inheritDoc}
      * <p>
      * Overridden to add the {@link Query} to the exception.
      * </p>
      * 
      * @see AbstractReplyCallback#asError(Reply, int, int, String)
      */
     @Override
     protected MongoDbException asError(final Reply reply, final int okValue,
             final int errorNumber, final String errorMessage) {
         return super.asError(reply, okValue, errorNumber, false, errorMessage,
                 myMessage);
     }
 
     /**
      * {@inheritDoc}
      * <p>
      * Overridden to construct a {@link MongoIteratorImpl} around the reply.
      * </p>
      * 
      * @see AbstractReplyCallback#convert(Reply)
      */
     @Override
     protected MongoIterator<Document> convert(final Reply reply)
             throws MongoDbException {
         Reply result = reply;
         if (isCommand()) {
             result = CommandCursorTranslator.translate(reply);
         }
         return new MongoIteratorImpl(myMessage, myClient, myAddress, result);
     }
 
     /**
      * {@inheritDoc}
      * <p>
      * Overridden to check if the server address has been set and if so then
      * pass the converted reply to the {@link #getForwardCallback() forward
      * callback}. Otherwise the call is dropped.
      * </p>
      */
     @Override
     protected void handle(final Reply reply) {
         myReply = reply;
         trigger();
     }
 
     /**
      * Returns true if the callback should expect a command formated cursor
      * reply.
      * 
      * @return True if the callback should expect a command formated cursor
      *         reply.
      */
     protected boolean isCommand() {
         return myCommand;
     }
 
     /**
      * Triggers the callback when the address and reply are set.
      */
     private void trigger() {
         if (!mySetOther.compareAndSet(false, true)) {
             super.handle(myReply);
         }
     }
 }