/*==========================================================================*\
 |  $Id: ImmediateProperties.java,v 1.1 2010/05/10 16:15:19 aallowat Exp $
 |*-------------------------------------------------------------------------*|
 |  Copyright (C) 2006-2009 Virginia Tech
 |
 |  This file is part of Web-CAT.
 |
 |  Web-CAT is free software; you can redistribute it and/or modify
 |  it under the terms of the GNU Affero General Public License as published
 |  by the Free Software Foundation; either version 3 of the License, or
 |  (at your option) any later version.
 |
 |  Web-CAT 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 General Public License for more details.
 |
 |  You should have received a copy of the GNU Affero General Public License
 |  along with Web-CAT; if not, see <http://www.gnu.org/licenses/>.
\*==========================================================================*/

package org.webcat.plugintester.util;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;

//-------------------------------------------------------------------------
/**
 * A subclass of the java.util.Properties class that must be initialized from
 * a file on disk, and which always keeps the in-memory property set in sync
 * with the contents on disk.
 * 
 * @author Tony Allevato
 * @version $Id: ImmediateProperties.java,v 1.1 2010/05/10 16:15:19 aallowat Exp $
 */
public class ImmediateProperties extends Properties
{
    //~ Constructors ..........................................................

    // ----------------------------------------------------------
    /**
     * Initializes a new instance of ImmediateProperties by loading them from
     * the specified file.
     * 
     * @param path the path to the file that backs this Properties instance.
     */
    public ImmediateProperties(String path)
    {
        super();
        
        this.path = path;
        
        try
        {
            FileInputStream stream = new FileInputStream(path);
            load(stream);
            stream.close();
        }
        catch (IOException e)
        {
            // Do nothing; start the property set empty.
        }
    }


    //~ Methods ...............................................................

    // ----------------------------------------------------------
    /**
     * Removes the specified property from the file.
     * 
     * @param key the name of the property to remove
     * @return the previous value of the property
     */
    @Override
    public Object remove(Object key)
    {
        Object previousValue = super.remove(key);
        writeToFile();
        return previousValue;
    }
    

    // ----------------------------------------------------------
    /**
     * Sets the value of the specified property.
     * 
     * @param key the name of the property to set
     * @param value the value of the property
     * @return the previous value of the property
     */
    @Override
    public Object put(Object key, Object value)
    {
        Object previousValue = super.put(key, value);
        writeToFile();
        return previousValue;
    }
    
    
    // ----------------------------------------------------------
    /**
     * Saves the current properties set to their associated file.
     */
    private void writeToFile()
    {
        try
        {
            FileOutputStream stream = new FileOutputStream(path);
            store(stream, null);
            stream.close();
        }
        catch (IOException e)
        {
            // Do nothing.
        }
    }

    
    //~ Instance/static variables .............................................

    /** The path to the file that backs this Properties instance. */
    private String path;

    private static final long serialVersionUID = -6139105936918525923L;
}