/*******************************************************************************
 * 
 * Copyright 2010 Alexandru Craciun, and individual contributors as indicated
 * by the @authors tag. 
 * 
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 3 of
 * the License, or (at your option) any later version.
 * 
 * This software 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 ******************************************************************************/
package org.netxilia.server.util;

import java.util.ArrayList;
import java.util.List;

/**
 * Use to simulate a list larger than its normal size. All the missing elements are lazily resolved by the element
 * resolver (for example returning the same element). Thus a list with identical elements can be easily simulated
 * without taking up the need memory.
 * 
 * WARNING: as the same object (maybe with its internal state modified) is returned each time, the object is valid after
 * a call to get method and BEFORE another call to the same method!
 * 
 * @author <a href='mailto:ax.craciun@gmail.com'>Alexandru Craciun</a>
 * 
 * @param <T>
 */
public class LazyArrayList<T> extends ArrayList<T> {

	private static final long serialVersionUID = 3473954523203990445L;
	private int totalSize;
	private ILazyElementResolver<T> lazyElementResolver;

	public LazyArrayList(int totalSize, ILazyElementResolver<T> lazyElementResolver) {
		this.totalSize = totalSize;
		this.lazyElementResolver = lazyElementResolver;
	}

	@Override
	public T get(int index) {
		if (index >= totalSize)
			throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + totalSize);
		if (index < super.size())
			return super.get(index);
		return lazyElementResolver.get(index);
	}

	@Override
	public int size() {
		return Math.max(totalSize, super.size());
	}

	public static void main(String[] args) {
		List<String> list = new LazyArrayList<String>(5, new ILazyElementResolver<String>() {
			public String get(int index) {
				return "lazy";
			}
		});
		list.add("a");
		list.add("b");
		list.add("c");

		for (String s : list)
			System.out.println(s);
	}
}