/*
 *
 *  * Copyright (c) 2011-2015 EPFL DATA Laboratory
 *  * Copyright (c) 2014-2015 The Squall Collaboration (see NOTICE)
 *  *
 *  * All rights reserved.
 *  *
 *  * Licensed under the Apache License, Version 2.0 (the "License");
 *  * you may not use this file except in compliance with the License.
 *  * You may obtain a copy of the License at
 *  *
 *  * http://www.apache.org/licenses/LICENSE-2.0
 *  *
 *  * Unless required by applicable law or agreed to in writing, software
 *  * distributed under the License is distributed on an "AS IS" BASIS,
 *  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  * See the License for the specific language governing permissions and
 *  * limitations under the License.
 *
 */

package ch.epfl.data.squall.thetajoin.matrix_assignment;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

/**
 * The idea is the same as ArrangementIterator.java.
 * But how instead of arranging the numbers, you arrange the sets (list of sets), each set is a list of integer.
 * 
 * @author Tam
 */
public class SetArrangementIterator implements Iterator<List<List<Integer>>>{
	
	private final List<List<Integer>> _sets;
	private final int _n;
	private int[] _pos;
	private boolean _hasNext = true;
	
	public SetArrangementIterator(List<List<Integer>> sets, int length){
		_sets = sets;
		_n = sets.size();
		_pos = new int[length];
		Arrays.fill(_pos, 0);
	}

	@Override
	public boolean hasNext() {
		return _hasNext;
	}

	@Override
	public List<List<Integer>> next() {
		List<List<Integer>> res = new ArrayList<List<Integer>>();
		for (int p : _pos){
			res.add(_sets.get(p));
		}
		
		for (int i = 0; i < _pos.length; i++){
			if (_pos[i] == _n - 1){
				if (i == _pos.length - 1) _hasNext = false;
				_pos[i] = 0;
			} else {
				_pos[i]++;
				break;
			}
		}
		
		return res;
	}

	@Override
	public void remove() {
		throw new UnsupportedOperationException();
	}
	
	public static void main(String... args){
		List<List<Integer>> powerSet = new ArrayList<List<Integer>>(Utilities.powerSet(Utilities.primeFactors(8)));
		SetArrangementIterator me = new SetArrangementIterator(powerSet, 3);
		int count = 0;
		while (me.hasNext()){
			count++;
			List<List<Integer>> combination = me.next();
			System.out.println(combination.toString());
		}
		assert count == powerSet.size() * powerSet.size() * powerSet.size();
	}

}