/*
    * #%L
    * SerialClientImpl.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;
  
  import java.io.Closeable;
  
  import com.allanbank.mongodb.Durability;
  import com.allanbank.mongodb.MongoClientConfiguration;
  import com.allanbank.mongodb.MongoCursorControl;
  import com.allanbank.mongodb.MongoDbException;
  import com.allanbank.mongodb.MongoIterator;
  import com.allanbank.mongodb.ReadPreference;
  import com.allanbank.mongodb.StreamCallback;
  import com.allanbank.mongodb.bson.Document;
  import com.allanbank.mongodb.bson.DocumentAssignable;
  import com.allanbank.mongodb.client.connection.Connection;
  
  /**
   * A specialization of the {@link ClientImpl} to always try to use the same
   * connection.
   * 
   * @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 2012-2013, Allanbank Consulting, Inc., All Rights Reserved
   */
  public class SerialClientImpl extends AbstractClient {
  
      /** If true then assertions have been enabled for the class. */
      protected static final boolean ASSERTIONS_ENABLED;
      static {
          ASSERTIONS_ENABLED = SerialClientImpl.class.desiredAssertionStatus();
      }
  
      /** The current active Connection to the MongoDB Servers. */
      private Connection myConnection;
  
      /** The delegate client for accessing connections. */
      private final ClientImpl myDelegate;
  
      /**
       * Create a new SerialClientImpl.
       * 
       * @param client
       *            The delegate client for accessing connections.
       */
      public SerialClientImpl(final ClientImpl client) {
          myDelegate = client;
      }
  
      /**
       * {@inheritDoc}
       * <p>
       * Overridden to close all of the open connections.
       * </p>
       * 
       * @see Closeable#close()
       */
      @Override
      public void close() {
          super.close();
  
          // Don't close the delegate.
          myConnection = null;
      }
  
      /**
       * {@inheritDoc}
       * <p>
       * Overridden to return the cluster stats from the delegate client.
       * </p>
       */
      @Override
      public ClusterStats getClusterStats() {
          return myDelegate.getClusterStats();
      }
  
      /**
       * {@inheritDoc}
       * <p>
       * Overridden to return the {@link ClusterType} of delegate
       * {@link ClientImpl}.
       * </p>
      */
     @Override
     public ClusterType getClusterType() {
         return myDelegate.getClusterType();
     }
 
     /**
      * {@inheritDoc}
      * <p>
      * Overridden to return the configuration used when the client was
      * constructed.
      * </p>
      */
     @Override
     public MongoClientConfiguration getConfig() {
         return myDelegate.getConfig();
     }
 
     /**
      * {@inheritDoc}
      * <p>
      * Overridden to return the configurations default durability.
      * </p>
      * 
      * @see Client#getDefaultDurability()
      */
     @Override
     public Durability getDefaultDurability() {
         return myDelegate.getDefaultDurability();
     }
 
     /**
      * {@inheritDoc}
      * <p>
      * Overridden to return the configurations default read preference.
      * </p>
      * 
      * @see Client#getDefaultReadPreference()
      */
     @Override
     public ReadPreference getDefaultReadPreference() {
         return myDelegate.getDefaultReadPreference();
     }
 
     /**
      * {@inheritDoc}
      * <p>
      * Overridden to forward to the delegate client.
      * </p>
      * 
      * @see Client#restart(DocumentAssignable)
      */
     @Override
     public MongoIterator<Document> restart(
             final DocumentAssignable cursorDocument)
             throws IllegalArgumentException {
         return myDelegate.restart(cursorDocument);
     }
 
     /**
      * {@inheritDoc}
      * <p>
      * Overridden to forward to the delegate client.
      * </p>
      * 
      * @see Client#restart(StreamCallback, DocumentAssignable)
      */
     @Override
     public MongoCursorControl restart(final StreamCallback<Document> results,
             final DocumentAssignable cursorDocument)
             throws IllegalArgumentException {
         return myDelegate.restart(results, cursorDocument);
     }
 
     /**
      * Tries to reuse the last connection used. If the connection it closed or
      * does not exist then the request is delegated to the {@link ClientImpl}
      * and the result cached for future requests.
      * 
      * @return The found connection.
      * @throws MongoDbException
      *             On a failure to talk to the MongoDB servers.
      */
     @Override
     protected Connection findConnection(final Message message1,
             final Message message2) throws MongoDbException {
         if ((myConnection == null) || !myConnection.isAvailable()) {
             myConnection = myDelegate.findConnection(message1, message2);
         }
 
         return myConnection;
     }
 }