/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2014 by RapidMiner and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapidminer.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.example.ExampleSet;
import com.rapidminer.operator.IOObject;
import com.rapidminer.operator.ports.OutputPort;

/** Assigns a predefined meta data object to an output port. Useful if operators
 *  newly generate IOObjects. If the meta data changes
 *  dynamically, can be modified by overriding {@link #modifyMetaData(MetaData)}. 
 *  
 *  @author Simon Fischer */
public class GenerateNewMDRule implements MDTransformationRule {

	private OutputPort outputPort;
	private MetaData unmodifiedMetaData;

	public GenerateNewMDRule(OutputPort outputPort, Class<? extends IOObject> clazz) {
		this(outputPort, ExampleSet.class.equals(clazz) ? new ExampleSetMetaData() : new MetaData(clazz));
	}

	public GenerateNewMDRule(OutputPort outputPort, MetaData unmodifiedMetaData) {	
		this.outputPort = outputPort;
		this.unmodifiedMetaData = unmodifiedMetaData;
	}

	@Override
	public void transformMD() {
		MetaData clone = this.unmodifiedMetaData.clone();
		clone.addToHistory(outputPort);
		outputPort.deliverMD(modifyMetaData(clone));
	}

	/** Modifies the standard 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;
	}

}