/*
    *   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.directory.ldap.client.api;
  
  
  import java.io.IOException;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.directory.api.i18n.I18n;
  import org.apache.directory.api.ldap.model.constants.Loggers;
  import org.apache.directory.api.ldap.model.cursor.AbstractCursor;
  import org.apache.directory.api.ldap.model.cursor.CursorException;
  import org.apache.directory.api.ldap.model.cursor.InvalidCursorPositionException;
  import org.apache.directory.api.ldap.model.cursor.SearchCursor;
  import org.apache.directory.api.ldap.model.entry.Entry;
  import org.apache.directory.api.ldap.model.exception.LdapException;
  import org.apache.directory.api.ldap.model.exception.LdapReferralException;
  import org.apache.directory.api.ldap.model.message.IntermediateResponse;
  import org.apache.directory.api.ldap.model.message.Referral;
  import org.apache.directory.api.ldap.model.message.Response;
  import org.apache.directory.api.ldap.model.message.SearchResultDone;
  import org.apache.directory.api.ldap.model.message.SearchResultEntry;
  import org.apache.directory.api.ldap.model.message.SearchResultReference;
  import org.apache.directory.ldap.client.api.exception.LdapConnectionTimeOutException;
  import org.apache.directory.ldap.client.api.future.SearchFuture;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * An implementation of Cursor based on the underlying SearchFuture instance.
   * 
   * Note: This is a forward only cursor hence the only valid operations are next(), get() and close() 
   * 
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class SearchCursorImpl extends AbstractCursor<Response> implements SearchCursor
  {
      /** A dedicated log for cursors */
      private static final Logger LOG_CURSOR = LoggerFactory.getLogger( Loggers.CURSOR_LOG.getName() );
  
      /** Speedup for logs */
      private static final boolean IS_DEBUG = LOG_CURSOR.isDebugEnabled();
  
      /** the search future */
      private SearchFuture future;
  
      /** wait time while polling for a SearchResponse */
      private long timeout;
  
      /** time units of timeout value */
      private TimeUnit timeUnit;
  
      /** a reference to hold the retrieved SearchResponse object from SearchFuture */
      private Response response;
  
      /** the done flag */
      private boolean done;
  
      /** a reference to hold the SearchResultDone response */
      private SearchResultDone searchDoneResp;
  
  
      /**
       * Instantiates a new search cursor.
       *
       * @param future the future
       * @param timeout the timeout
       * @param timeUnit the time unit
       */
      public SearchCursorImpl( SearchFuture future, long timeout, TimeUnit timeUnit )
      {
          if ( IS_DEBUG )
          {
              LOG_CURSOR.debug( "Creating SearchCursorImpl {}", this );
          }
  
          this.future = future;
          this.timeout = timeout;
          this.timeUnit = timeUnit;
      }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean next() throws LdapException, CursorException
     {
         if ( done )
         {
             return false;
         }
 
         try
         {
             if ( future.isCancelled() )
             {
                 response = null;
                 done = true;
                 return false;
             }
 
             response = future.get( timeout, timeUnit );
         }
         catch ( Exception e )
         {
             LdapException ldapException = new LdapException( LdapNetworkConnection.NO_RESPONSE_ERROR, e );
 
             // Send an abandon request
             if ( !future.isCancelled() )
             {
                 future.cancel( true );
             }
 
             // close the cursor
             try 
             {
                 close( ldapException );
             }
             catch ( IOException ioe )
             {
                 throw new LdapException( ioe.getMessage(), ioe );
             }
 
             throw ldapException;
         }
 
         if ( response == null )
         {
             future.cancel( true );
 
             throw new LdapConnectionTimeOutException( LdapNetworkConnection.TIME_OUT_ERROR );
         }
 
         done = response instanceof SearchResultDone;
 
         if ( done )
         {
             searchDoneResp = ( SearchResultDone ) response;
 
             response = null;
         }
 
         return !done;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public Response get() throws InvalidCursorPositionException
     {
         if ( !available() )
         {
             throw new InvalidCursorPositionException();
         }
 
         return response;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public SearchResultDone getSearchResultDone()
     {
         return searchDoneResp;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean available()
     {
         return response != null;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void close() throws IOException
     {
         if ( IS_DEBUG )
         {
             LOG_CURSOR.debug( "Closing SearchCursorImpl {}", this );
         }
 
         close( null );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void close( Exception cause ) throws IOException
     {
         if ( IS_DEBUG )
         {
             LOG_CURSOR.debug( "Closing SearchCursorImpl {}", this );
         }
 
         if ( done )
         {
             super.close();
             return;
         }
 
         if ( !future.isCancelled() )
         {
             future.cancel( true );
         }
 
         if ( cause != null )
         {
             super.close( cause );
         }
         else
         {
             super.close();
         }
     }
 
 
     // rest of all operations will throw UnsupportedOperationException
 
     /**
      * This operation is not supported in SearchCursor.
      * {@inheritDoc}
      */
     @Override
     public void after( Response element ) throws LdapException, CursorException
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_02014_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "after( Response element )" ) ) );
     }
 
 
     /**
      * This operation is not supported in SearchCursor.
      * {@inheritDoc}
      */
     @Override
     public void afterLast() throws LdapException, CursorException
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_02014_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "afterLast()" ) ) );
     }
 
 
     /**
      * This operation is not supported in SearchCursor.
      * {@inheritDoc}
      */
     @Override
     public void before( Response element ) throws LdapException, CursorException
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_02014_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "before( Response element )" ) ) );
     }
 
 
     /**
      * This operation is not supported in SearchCursor.
      * {@inheritDoc}
      */
     @Override
     public void beforeFirst() throws LdapException, CursorException
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_02014_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "beforeFirst()" ) ) );
     }
 
 
     /**
      * This operation is not supported in SearchCursor.
      * {@inheritDoc}
      */
     @Override
     public boolean first() throws LdapException, CursorException
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_02014_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "first()" ) ) );
     }
 
 
     /**
      * This operation is not supported in SearchCursor.
      * {@inheritDoc}
      */
     @Override
     public boolean last() throws LdapException, CursorException
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_02014_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "last()" ) ) );
     }
 
 
     /**
      * This operation is not supported in SearchCursor.
      * {@inheritDoc}
      */
     @Override
     public boolean previous() throws LdapException, CursorException
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_02014_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "previous()" ) ) );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isDone()
     {
         return done;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isReferral()
     {
         return response instanceof SearchResultReference;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public Referral getReferral() throws LdapException
     {
         if ( isReferral() )
         {
             return ( ( SearchResultReference ) response ).getReferral();
         }
 
         throw new LdapException();
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isEntry()
     {
         return response instanceof SearchResultEntry;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public Entry getEntry() throws LdapException
     {
         if ( isEntry() )
         {
             return ( ( SearchResultEntry ) response ).getEntry();
         }
         
         if ( isReferral() )
         {
             Referral referral = ( ( SearchResultReference ) response ).getReferral();
             throw new LdapReferralException( referral.getLdapUrls() );
         }
 
         throw new LdapException();
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isIntermediate()
     {
         return response instanceof IntermediateResponse;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public IntermediateResponse getIntermediate() throws LdapException
     {
         if ( isEntry() )
         {
             return ( IntermediateResponse ) response;
         }
 
         throw new LdapException();
     }
 }