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/*
 *  Copyright (C) 2012 Ed Schaller 
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package net.darkmist.alib.io;

import java.io.File;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.Queue;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class DirTraverser
{
	private static final Class CLASS = DirTraverser.class;
	private static final Logger logger = LoggerFactory.getLogger(CLASS);

	private FileHandler fileHandler;
	private Queue frontier;

	/**
	 * Create a queue for use. This is here to ease changing of the
	 * default quque implementation.
	 * @return empty queue.
	 */
	private static final Queue newQueue()
	{
		return new LinkedList();
	}

	private static final Queue newQueue(File initial)
	{
		Queue ret = newQueue();

		ret.add(initial);
		return ret;
	}

	public DirTraverser(Queue frontier, FileHandler fileHandler)
	{
		if(frontier == null)
			frontier = newQueue();
		this.frontier = frontier;
		this.fileHandler = fileHandler;
	}

	public DirTraverser(File start, FileHandler fileHandler)
	{
		this(newQueue(start), fileHandler);
	}

	protected void onFile(File file)
	{
		if(fileHandler != null)
			fileHandler.handleFile(file);
	}

	private void onRawFile(File file)
	{
		if(file.isDirectory())
			frontier.add(file);
		else
			onFile(file);
	}

	private static  T[] sort(T...a)
	{
		Arrays.sort(a);
		return a;
	}

	public void run()
	{
		File dir;

		while(frontier.size() > 0 && (dir = frontier.remove())!=null)
		{
			if((dir = frontier.remove())==null)
			{
				logger.warn("Frontier queue contained unepected null element! Ignoring");
				continue;
			}
			if(dir.isDirectory())
			{
				File[] files = dir.listFiles();
				if(files != null)
					for(File file : sort(dir.listFiles()))
						onRawFile(file);
			}
			else
				onFile(dir);
		}
	}
}