/*
 *  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.collections;

import com.rapidminer.operator.IOObject;
import com.rapidminer.operator.IOObjectCollection;
import com.rapidminer.operator.Operator;
import com.rapidminer.operator.OperatorDescription;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.ports.InputPort;
import com.rapidminer.operator.ports.OutputPort;
import com.rapidminer.operator.ports.metadata.CollectionMetaData;
import com.rapidminer.operator.ports.metadata.MDTransformationRule;
import com.rapidminer.operator.ports.metadata.MetaData;

/** Turns a collection of collections into a flat collection.
 * 
 * @author Simon Fischer 
 *
 */
public class UnfoldOperator extends Operator {

	private final InputPort collectionInput = getInputPorts().createPort("collection", new CollectionMetaData());
	private final OutputPort flatOutput = getOutputPorts().createPort("flat");
	
	public UnfoldOperator(OperatorDescription description) {
		super(description);
		getTransformer().addRule(new MDTransformationRule() {
			@Override
			public void transformMD() {
				MetaData md = collectionInput.getMetaData();
				if ((md != null) && (md instanceof CollectionMetaData)) {
					flatOutput.deliverMD(new CollectionMetaData(((CollectionMetaData)md).getElementMetaDataRecursive()));
				} else {
					flatOutput.deliverMD(null);
				}
			}
		});
	}
	
	@Override
	public void doWork() throws OperatorException {
		IOObjectCollection<?> collection = collectionInput.getData(IOObjectCollection.class);
		flatOutput.deliver(new IOObjectCollection<IOObject>(collection.getObjectsRecursive()));
	}

}