/*
* Copyright 2003-2010 Tufts University  Licensed under the
 * Educational Community 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.osedu.org/licenses/ECL-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 tufts.vue;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.StringTokenizer;
import edu.tufts.vue.preferences.implementations.StringPreference;
import edu.tufts.vue.preferences.interfaces.VuePreference;

public class RecentlyOpenedFilesManager 
{
	private static final String maxSize = "20";
	 private static VuePreference openFilePref = StringPreference.create(
				edu.tufts.vue.preferences.PreferenceConstants.FILES_CATEGORY,
				"recentlyOpenedFiles", 
				"Recently Opened Files", 
				"Number of Recently Opened Files to maintain",
				maxSize,
				false);
	
	private LinkedList list = new LinkedList();
	private int maxsize; 
	private static RecentlyOpenedFilesManager _instance; 
	
	
	 // For lazy initialization
	 public static synchronized RecentlyOpenedFilesManager getInstance() {
	  if (_instance==null) {
	   _instance = new RecentlyOpenedFilesManager();
	  }
	  return _instance;
	 }	
	 
	 public VuePreference getPreference()
	 {
		 return openFilePref;
	 }
	 
	private RecentlyOpenedFilesManager()
	{
		StringTokenizer tokens = new StringTokenizer((String)openFilePref.getValue(),"*");
		
		while (tokens.hasMoreTokens())
		{
			list.add(tokens.nextToken());
		}
		maxsize = getMaxSize();
		
		return;
	}
	
	private int getMaxSize()
	{
            if (DEBUG.Enabled) return 50;
            
            maxsize = Integer.valueOf((String)list.getFirst());
            return maxsize;
	}
	
	private void setMaxSize(int i)
	{
		list.removeFirst();
		list.set(0, (Object)(new Integer(i).toString()));
		maxsize = i;
	}
	
	public int getFileListSize()
	{
		return list.subList(1, list.size()).size();
	}
	
	public List getRecentlyOpenedFiles()
	{
		return list.subList(1, list.size());
	}
	
	public void updateRecentlyOpenedFiles(String s)
	{
		//try to add this file to the list and update the preference
		Iterator i = list.iterator();
		
		//update the maxFile count in case it changed...
		list.remove(0);
		list.add(0, maxSize);
		
		//is file already in list?
		if (list.contains(s))
		{
			int index = list.indexOf(s);
			list.remove(index);
			list.add(1, s);
			
		}
		else
		{
			//if it's not in the list add it to the top and deal with it later
			list.add(1,s);
		}
		
		//trim list if necessary...
		while (list.size() > (maxsize + 1))
			list.removeLast();
		
		//build a new pref String;
		StringBuffer sbuffer = new StringBuffer();
		
		i = list.iterator();
		
		while (i.hasNext())
		{
			sbuffer.append((String)i.next());
			sbuffer.append("*");
		}
		//update the preference
		openFilePref.setValue(sbuffer.toString());
	}
}