/*
 *  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.io.IOException;
import java.net.URL;
import java.util.AbstractMap;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
/**
 * @author Tobias Malbrecht
 */
public abstract class ParentResolvingMap<K,V> extends AbstractMap<K,V> implements Map<K,V>{

	private final Map<K,V> delegate = new HashMap<K,V>();

	public ParentResolvingMap() {				
	}

	public void parseProperties(String resourceName, String prefix, String suffix, ClassLoader classLoader) throws IOException {
		Properties groupProps = new Properties();
		URL resource = classLoader.getResource(resourceName);
		if (resource == null) {
			LogService.getRoot().warning("Group properties resource '"+resourceName + "' not found.");
		} else {			
			groupProps.load(resource.openStream());			
			for (String propKey : groupProps.stringPropertyNames()) {				
				if (propKey.startsWith(prefix) && (propKey.endsWith(suffix))) {
					String keyString = propKey.substring(prefix.length());
					keyString = keyString.substring(0, keyString.length() - suffix.length());
					K mapKey = parseKey(keyString, classLoader);
					V value = parseValue(groupProps.getProperty(propKey), classLoader);					
					delegate.put(mapKey, value);
				}
			}
		}
	}

	protected abstract V parseValue(String value, ClassLoader classLoader);
	protected abstract K parseKey(String key, ClassLoader classLoader);
	protected abstract K getParent(K child);
	protected abstract V getDefault();
	
	@Override
	@SuppressWarnings("unchecked")
	public V get(Object key) {
		while (key != null) {
			V value = delegate.get(key);
			if (value != null) {
				return value;
			} else {
				key = getParent((K)key);
			}
		}	
		return getDefault();
	}
	
	@Override
	public V put(K key, V value) {
		return delegate.put(key, value);
	}
	
	@Override
	public Set<Map.Entry<K,V>> entrySet() {
		return delegate.entrySet();
	}
}