/*
    *  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.server.core.partition.impl.btree;
  
  
  import java.io.IOException;
  import java.util.Iterator;
  
  import org.apache.directory.api.i18n.I18n;
  import org.apache.directory.api.ldap.model.constants.Loggers;
  import org.apache.directory.api.ldap.model.cursor.ClosureMonitor;
  import org.apache.directory.api.ldap.model.cursor.Cursor;
  import org.apache.directory.api.ldap.model.cursor.CursorException;
  import org.apache.directory.api.ldap.model.cursor.CursorIterator;
  import org.apache.directory.api.ldap.model.cursor.Tuple;
  import org.apache.directory.api.ldap.model.exception.LdapException;
  import org.apache.directory.server.core.api.partition.PartitionTxn;
  import org.apache.directory.server.xdbm.AbstractIndexCursor;
  import org.apache.directory.server.xdbm.IndexEntry;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * A Cursor which adapts an underlying Tuple based Cursor to one which returns
   * IndexEntry objects rather than tuples.
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class IndexCursorAdaptor<K> extends AbstractIndexCursor<K>
  {
      /** 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();
  
      @SuppressWarnings("unchecked")
      final Cursor<Tuple> wrappedCursor;
      final IndexEntry<K, String> forwardEntry;
  
  
      /**
       * Creates an IndexCursorAdaptor which wraps and adapts a Cursor from a table to
       * one which returns an IndexEntry.
       *
       * @param partitionTxn The transaction to use
       * @param wrappedCursor the Cursor being adapted
       * @param forwardIndex true for a cursor over a forward index, false for
       * one over a reverse index
       */
      @SuppressWarnings("unchecked")
      public IndexCursorAdaptor( PartitionTxn partitionTxn, Cursor<Tuple> wrappedCursor, boolean forwardIndex )
      {
          this.wrappedCursor = wrappedCursor;
  
          forwardEntry = new IndexEntry<>();
          this.partitionTxn = partitionTxn;
  
          if ( IS_DEBUG )
          {
              LOG_CURSOR.debug( "Creating IndexCursorAdaptor {}", this );
          }
      }
  
  
      /**
       * {@inheritDoc}
       */
      @Override
      public boolean available()
      {
          return wrappedCursor.available();
      }
  
  
      /**
       * {@inheritDoc}
       */
      @Override
      public void before( IndexEntry<K, String> element ) throws LdapException, CursorException
      {
         wrappedCursor.before( element.getTuple() );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void after( IndexEntry<K, String> element ) throws LdapException, CursorException
     {
         wrappedCursor.after( element.getTuple() );
     }
 
 
     /**
      * {@inheritDoc}
      */
     public void beforeFirst() throws LdapException, CursorException
     {
         wrappedCursor.beforeFirst();
     }
 
 
     /**
      * {@inheritDoc}
      */
     public void afterLast() throws LdapException, CursorException
     {
         wrappedCursor.afterLast();
     }
 
 
     /**
      * {@inheritDoc}
      */
     public boolean first() throws LdapException, CursorException
     {
         return wrappedCursor.first();
     }
 
 
     /**
      * {@inheritDoc}
      */
     public boolean last() throws LdapException, CursorException
     {
         return wrappedCursor.last();
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isClosed()
     {
         return wrappedCursor.isClosed();
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean previous() throws LdapException, CursorException
     {
         return wrappedCursor.previous();
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean next() throws LdapException, CursorException
     {
         return wrappedCursor.next();
     }
 
 
     /**
      * {@inheritDoc}
      */
     @SuppressWarnings("unchecked")
     public IndexEntry<K, String> get() throws CursorException
     {
         Tuple<K, String> tuple = wrappedCursor.get();
         forwardEntry.setTuple( tuple );
 
         return forwardEntry;
     }
 
 
     @Override
     public final void setClosureMonitor( ClosureMonitor monitor )
     {
         wrappedCursor.setClosureMonitor( monitor );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void close() throws IOException
     {
         if ( IS_DEBUG )
         {
             LOG_CURSOR.debug( "Closing IndexCursorAdaptor {}", this );
         }
 
         wrappedCursor.close();
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void close( Exception reason ) throws IOException
     {
         if ( IS_DEBUG )
         {
             LOG_CURSOR.debug( "Closing IndexCursorAdaptor {}", this );
         }
 
         wrappedCursor.close( reason );
     }
 
 
     @Override
     public Iterator<IndexEntry<K, String>> iterator()
     {
         return new CursorIterator<>( this );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isAfterLast()
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_13102_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "isAfterLast()" ) ) );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isBeforeFirst()
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_13102_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "isBeforeFirst()" ) ) );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isFirst()
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_13102_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "isFirst()" ) ) );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isLast()
     {
         throw new UnsupportedOperationException( I18n.err( I18n.ERR_13102_UNSUPPORTED_OPERATION, getClass().getName()
             .concat( "." ).concat( "isLast()" ) ) );
     }
 
 
     /**
      * {@inheritDoc}
      */
     protected String getUnsupportedMessage()
     {
         return UNSUPPORTED_MSG;
     }
 
 
     /**
      * @see Object#toString()
      */
     @Override
     public String toString( String tabs )
     {
         StringBuilder sb = new StringBuilder();
 
         sb.append( tabs ).append( "IndexCursorAdaptor (" );
 
         if ( available() )
         {
             sb.append( "available)" );
         }
         else
         {
             sb.append( "absent)" );
         }
 
         sb.append( " :\n" );
 
         sb.append( wrappedCursor.toString( tabs + "    " ) );
 
         return sb.toString();
     }
 
 
     /**
      * @see Object#toString()
      */
     public String toString()
     {
         return toString( "" );
     }
 }