/*
 *  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.io.process.rules;

import java.util.Collection;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

import com.rapidminer.gui.tools.VersionNumber;
import com.rapidminer.io.process.XMLImporter;
import com.rapidminer.operator.ExecutionUnit;
import com.rapidminer.operator.Operator;
import com.rapidminer.operator.OperatorChain;
import com.rapidminer.operator.SimpleOperatorChain;
/**
 * This parse rule replaces any unnecessary operator chain rule.
 * 
 * @author Sebastian Land
 */
public class DeleteUnnecessaryOperatorChainRule extends AbstractGenericParseRule {
	private static final VersionNumber APPLIES_UNTIL = new VersionNumber(5, 0, 0, false, 0, false, 0);
	
	public String apply(final Operator operator, VersionNumber processVersion, final XMLImporter importer) {		
		if (operator.getClass() == SimpleOperatorChain.class && (processVersion == null || processVersion.compareTo(APPLIES_UNTIL) <= 0)) {
			importer.doAfterTreeConstruction(new Runnable() {
				public void run() {
					OperatorChain parent = operator.getParent();
					if (parent != null) {
						// then its not root: search for subprocess containing operator
						for (ExecutionUnit unit: parent.getSubprocesses()) {
							Collection<Operator> innerOperators = unit.getChildOperators();
							if (innerOperators.size() == 1) {
								// and if only contains this operator
								if (innerOperators.iterator().next() == operator) {
									// then place children directly
									importer.addMessage("<code>OperatorChain</code>s are unneccessary if they are the only operator inside a subprocess. Removed unnecessary OperatorChain <var>"+operator.getName()+"</var> in <var>" + parent.getName() + "</var>.");
									OperatorChain self = (OperatorChain) operator;
									for(Operator child : new LinkedList<Operator>(self.getSubprocess(0).getOperators())) {
										child.remove();
										unit.addOperator(child);
									}
									self.remove();
								}
							}
						}
					}
				}
			});	
		}
		return null;
	}

	@Override
	public List<String> getApplicableOperatorKeys() {
		return Collections.singletonList("subprocess");
	}
	
	
}