/*
 *  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.jdbm;


import java.io.IOException;

import javax.naming.NamingException;

import org.apache.directory.server.core.partition.impl.btree.Tuple;
import org.apache.directory.server.core.partition.impl.btree.TupleBrowser;


/**
 * TupleBrowser wrapper for Jdbm based TupleBrowsers.
 *
 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
 * @version $Rev$
 */
public class JdbmTupleBrowser implements TupleBrowser
{
    /** underlying wrapped jdbm.helper.TupleBrowser */
    private jdbm.helper.TupleBrowser jdbmBrowser;
    /** safe temp jdbm.helper.Tuple used to store next/previous tuples */
    private jdbm.helper.Tuple jdbmTuple = new jdbm.helper.Tuple();


    /**
     * Creates a JdbmTupleBrowser.
     *
     * @param jdbmBrowser JDBM browser to wrap.
     */
    public JdbmTupleBrowser(jdbm.helper.TupleBrowser jdbmBrowser)
    {
        this.jdbmBrowser = jdbmBrowser;
    }


    /**
     * @see TupleBrowser#getNext(org.apache.directory.server.core.partition.impl.btree.Tuple)
     */
    public boolean getNext( Tuple tuple ) throws NamingException
    {
        boolean isSuccess = false;

        synchronized ( jdbmTuple )
        {
            try
            {
                isSuccess = jdbmBrowser.getNext( jdbmTuple );
            }
            catch ( IOException ioe )
            {
                NamingException ne = new NamingException( "Failed on call to jdbm TupleBrowser.getNext()" );
                ne.setRootCause( ioe );
                throw ne;
            }

            if ( isSuccess )
            {
                tuple.setKey( jdbmTuple.getKey() );
                tuple.setValue( jdbmTuple.getValue() );
            }
        }

        return isSuccess;
    }


    /**
     * @see TupleBrowser#getPrevious(Tuple)
     */
    public boolean getPrevious( Tuple tuple ) throws NamingException
    {
        boolean isSuccess = false;

        synchronized ( jdbmTuple )
        {
            try
            {
                isSuccess = jdbmBrowser.getPrevious( jdbmTuple );
            }
            catch ( IOException ioe )
            {
                NamingException ne = new NamingException( "Failed on call to jdbm TupleBrowser.getPrevious()" );
                ne.setRootCause( ioe );
                throw ne;
            }

            if ( isSuccess )
            {
                tuple.setKey( jdbmTuple.getKey() );
                tuple.setValue( jdbmTuple.getValue() );
            }
        }

        return isSuccess;
    }
}