/*
 *  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.operator.preprocessing.filter;

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

import com.rapidminer.example.ExampleSet;
import com.rapidminer.example.set.SortedExampleSet;
import com.rapidminer.operator.OperatorDescription;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.annotation.ResourceConsumptionEstimator;
import com.rapidminer.operator.preprocessing.AbstractDataProcessing;
import com.rapidminer.parameter.ParameterType;
import com.rapidminer.tools.OperatorResourceConsumptionHandler;
import com.rapidminer.tools.RandomGenerator;


/** 
 *  This operator creates a new, shuffled ExampleSet by making creating 
 *  a shuffled view using a {@link SortedExampleSet}
 *
 *  @author Sebastian Land, Ingo Mierswa
 */
public class PermutationOperator extends AbstractDataProcessing {

	public PermutationOperator(OperatorDescription description) {
		super(description);
	}

	@Override
	public ExampleSet apply(ExampleSet exampleSet) throws OperatorException {         
		
		ArrayList<Integer> indicesCollection = new ArrayList<Integer>(exampleSet.size());
		for (int i = 0; i < exampleSet.size(); i++)
			indicesCollection.add(i);
		
		Collections.shuffle(indicesCollection, RandomGenerator.getRandomGenerator(this));
		
		int[] indices = new int[exampleSet.size()];
		for (int i = 0; i < exampleSet.size(); i++)
			indices[i] = indicesCollection.get(i);
		
		return new SortedExampleSet(exampleSet, indices);
	}

	@Override
	public List<ParameterType> getParameterTypes() {
		List<ParameterType> types = super.getParameterTypes();

		types.addAll(RandomGenerator.getRandomGeneratorParameters(this));

		return types;
	}
	
	@Override
	public boolean writesIntoExistingData() {
		return false;
	}
	
	@Override
	public ResourceConsumptionEstimator getResourceConsumptionEstimator() {
		return OperatorResourceConsumptionHandler.getResourceConsumptionEstimator(getInputPort(), PermutationOperator.class, null);
	}
}