/*******************************************************************************
 * Copyright (c) 2010-2015 Henshin developers. All rights reserved. 
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     TU Berlin, University of Luxembourg, SES S.A.
 *******************************************************************************/
package de.tub.tfs.muvitor.ui.utils;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Random;

public final class GenericUtils {
	
	static private final Random random = new Random();
	
	static public final <K, V> List<K> deleteValueFromMap(final Map<K, V> map, final V value,
			final boolean once) {
		final ArrayList<K> deletedKeys = new ArrayList<K>();
		for (final Iterator<Entry<K, V>> i = map.entrySet().iterator(); i.hasNext();) {
			final Entry<K, V> entry = i.next();
			if (entry.getValue() == value) {
				deletedKeys.add(entry.getKey());
				i.remove();
				if (once) {
					return deletedKeys;
				}
			}
		}
		return deletedKeys;
	}
	
	static public final <T> T getRandom(final List<T> list) {
		if (list.isEmpty()) {
			return null;
		}
		if (list.size() == 1) {
			return list.get(0);
		}
		int randomInt = random.nextInt();
		if (randomInt < 0) {
			randomInt = -randomInt;
		}
		final int pos = randomInt % list.size();
		return list.get(pos);
	}
	
	static public final <V, K> K inverseLookup(final HashMap<K, V> map, final V value) {
		for (final Entry<K, V> entry : map.entrySet()) {
			if (entry.getValue() == value) {
				return entry.getKey();
			}
		}
		return null;
	}
	
	private GenericUtils() {
	}
	
}