package dk.itu.oop.lecture4;

import java.util.*;

public class DrawRandom {
	private Object[] elements;
	private int N;
	private int left;
	private Random rnd = new Random();

	/* pre: c is not null
	 * post: all elements from c can be drawn
	 */
	public DrawRandom(Collection c){
		N = left = c.size();
		elements = new Object[N];
		Iterator itr = c.iterator();
		for( int i = 0; i< N; i++ )
			elements[i] = itr.next();
	}

	/* pre: true
	 * post: are there more elements to draw
	 */
	public boolean hasMore(){
		return left > 0;
	}

	/* pre: hasMore
	 * post: return value belongs to initial collection,
	 *       return vaule will not again be drawn
	 */
	public Object drawOne(){
		int index = rnd.nextInt( N );
		System.out.println("["+index+":"+left+"]");
		while ( elements[index] == null )
			index = (index + 1)%N;
		Object ret = elements[index];
		elements[index] = null;
		left--;
		return ret;
	}

}