/*
 *  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.ports.metadata;

import com.rapidminer.operator.ports.InputPorts;
import com.rapidminer.operator.ports.OutputPorts;

/** Passes output <var>i</var> to input <var>i</var>.
 *  generated by a {@link PortPairExtender}.
 *  
 * @author Simon Fischer
 */
public class ManyToManyPassThroughRule implements MDTransformationRule {

	private InputPorts inputPorts;
	private OutputPorts outputPorts;
	
	public ManyToManyPassThroughRule(InputPorts inputPorts, OutputPorts outputPorts) {	
		this.inputPorts = inputPorts;
		this.outputPorts = outputPorts;
	}

	@Override
	public void transformMD() {
		assert(inputPorts.getNumberOfPorts() == outputPorts.getNumberOfPorts());
		int numIn = inputPorts.getNumberOfPorts();
		int numOut = outputPorts.getNumberOfPorts();
		int num = numIn < numOut ? numIn : numOut;
		for (int i = 0; i < num; i++) {
			MetaData metaData = inputPorts.getPortByIndex(i).getMetaData();
			if (metaData != null) {
				metaData = metaData.clone();
				metaData.addToHistory(outputPorts.getPortByIndex(i));
				outputPorts.getPortByIndex(i).deliverMD(modifyMetaData(metaData));
			} else {
				outputPorts.getPortByIndex(i).deliverMD(null);
			}
		}
	}
	
	/** Modifies the received meta data before it is passed to the output. Can be used
	 *  if the transformation depends on parameters etc. The default implementation
	 *  just returns the original. Subclasses may safely modify the meta data, since
	 *  a copy is used for this method. */
	public MetaData modifyMetaData(MetaData unmodifiedMetaData) {
		return unmodifiedMetaData;
	}
}