D-Net

package eu.dnetlib.enabling.resultset.client;

import java.util.Iterator;

import java.util.LinkedList;

import java.util.List;

import java.util.NoSuchElementException;

import java.util.Queue;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import eu.dnetlib.enabling.resultset.client.utils.ResultSetRuntimeException;

import eu.dnetlib.enabling.resultset.client.utils.ResultSetTimeoutException;

import eu.dnetlib.enabling.resultset.rmi.ResultSetException;

import eu.dnetlib.enabling.resultset.rmi.ResultSetService;

/**

 * 

 * @author claudio

 *

 */

public class ResultSetClientIterator implements Iterator<String> {

	/**

	 * logger

	 */

	private static final Log log = LogFactory.getLog(ResultSetClientIterator.class);

	/**

	 * the page source 

	 */

	private ResultSetPageProvider pageProvider;

	/**

	 * buffer used to provide a single element for the next() method

	 */

	private Queue<String> buffer;

	public ResultSetClientIterator(ResultSetService resultSet, String rsId) 

		throws ResultSetRuntimeException {

		pageProvider = new ResultSetPageProvider(resultSet, rsId);

		buffer = new LinkedList<String>();

	}

	public ResultSetClientIterator(ResultSetService resultSet, String rsId, int pageSize) {

		this(resultSet, rsId);

		pageProvider.setPageSize(pageSize);

	}

	public ResultSetClientIterator(ResultSetService resultSet, String rsId, int pageSize, long timeout) {

		this(resultSet, rsId, pageSize);

		pageProvider.setMaxWaitTime(timeout);

	}

	/**

	 * Tries to refill the buffer with a nextPage()

	 * @return true if the buffer was filled successfully, false otherwise

	 * @throws ResultSetTimeoutException in case of timeout

	 * @throws ResultSetException 

	 * @throws ResultSetException 

	 */

	private boolean refillBuffer() throws ResultSetTimeoutException, ResultSetRuntimeException {

		List<String> page = pageProvider.nextPage();

		if (page != null && !page.isEmpty()) {

			buffer.addAll(page);

			return true;

		}

		return false;

	}

	@Override

	public boolean hasNext() {

		if (!buffer.isEmpty())

			return true;

		return refillBuffer();

	}

	@Override

	public String next() {

		if (!hasNext()) {

			log.info("NoSuchElementException");

			throw new NoSuchElementException();

		}

		return buffer.poll();

	}

	@Override

	public void remove() {

		throw new UnsupportedOperationException();

	}

}