/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program 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.
 *
 *  This program 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.tools;

import java.util.Enumeration;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ResourceBundle;

/**
 * This class represents an extensible resource bundle, where other resource bundles might be added.
 * These are searched if the key isn't contained in the previously added bundles.
 * 
 * @author Sebastian Land
 */
public class ExtensibleResourceBundle extends ResourceBundle  {

	private class KeyEnumeration implements Enumeration<String> {
		private Iterator<ResourceBundle> bundleIterator = bundles.iterator();
		private Enumeration<String> keyIterator;
		@Override
		public boolean hasMoreElements() {
			if (keyIterator == null || !keyIterator.hasMoreElements()) {
				while (bundleIterator.hasNext() && (keyIterator == null || !keyIterator.hasMoreElements())) {
					keyIterator = bundleIterator.next().getKeys();
				}
			}
			if (keyIterator == null || !keyIterator.hasMoreElements())
				return false;
			return true;
		}

		@Override
		public String nextElement() {
			if (keyIterator == null) {
				keyIterator = bundleIterator.next().getKeys();
			}
			while (!keyIterator.hasMoreElements()) {
				keyIterator = bundleIterator.next().getKeys();
			}			
			return keyIterator.nextElement();
		}
	}
	
	private List<ResourceBundle> bundles = new LinkedList<ResourceBundle>();
	
	public ExtensibleResourceBundle(ResourceBundle parent) {
		bundles.add(parent);
	}
	
	/**
	 * This method extends this resource bundle with the properties set by the given
	 * bundle. If those properties are already contained, they will be ignored.
	 */
	public void addResourceBundle(ResourceBundle bundle) {
		bundles.add(bundle);
	}
	
	/**
	 * This method extends this resource bundle with the properties set by the given bundle.
	 * If those properties were already contained, they are overwritten by the new bundle's settings.
	 */
	public void addResourceBundleAndOverwrite(ResourceBundle bundle) {
		bundles.add(0, bundle);
	}
	
	@Override
	public Enumeration<String> getKeys() {
		return new KeyEnumeration();
	}

	@Override
	protected Object handleGetObject(String key) {
		for (ResourceBundle bundle: bundles) {
			if (bundle.containsKey(key))
				return bundle.getObject(key);
		}
		return null;
	}

}