/*
 *  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.meta;

import com.rapidminer.example.ExampleSet;
import com.rapidminer.example.set.SplittedExampleSet;
import com.rapidminer.operator.OperatorChain;
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.PortPairExtender;
import com.rapidminer.operator.ports.metadata.ExampleSetMetaData;
import com.rapidminer.operator.ports.metadata.ExampleSetPassThroughRule;
import com.rapidminer.operator.ports.metadata.MDInteger;
import com.rapidminer.operator.ports.metadata.SetRelation;
import com.rapidminer.operator.ports.metadata.SimplePrecondition;
import com.rapidminer.operator.ports.metadata.SubprocessTransformRule;
import com.rapidminer.parameter.UndefinedParameterError;


/**
 * <p>An operator chain that split an {@link ExampleSet} into two disjoint parts
 * and applies the first child operator on the first part and applies the second
 * child on the second part and the result of the first child. The total result
 * is the result of the second operator.</p>
 * 
 * <p>Subclasses must define how the example set is divided.</p>
 * 
 * @author Ingo Mierswa
 */
public abstract class AbstractSplitChain extends OperatorChain {

	private final InputPort exampleSetInput = getInputPorts().createPort("example set");

	/** The input example set's first part is sent here. */
	private final OutputPort firstNestedExampleSetOutput = getSubprocess(0).getInnerSources().createPort("example set");	
	private final PortPairExtender firstToSecondExtender = new PortPairExtender("through", getSubprocess(0).getInnerSinks(), getSubprocess(1).getInnerSources());

	private final OutputPort secondNestedExampleSetOutput = getSubprocess(1).getInnerSources().createPort("example set");

	private final PortPairExtender secondToOutputExtender = new PortPairExtender("through", getSubprocess(1).getInnerSinks(), getOutputPorts());

	public AbstractSplitChain(OperatorDescription description) {
		super(description, "First Part", "Second Part");
		firstToSecondExtender.start();
		secondToOutputExtender.start();

		exampleSetInput.addPrecondition(new SimplePrecondition(exampleSetInput, new ExampleSetMetaData()));

		getTransformer().addRule(new ExampleSetPassThroughRule(exampleSetInput, firstNestedExampleSetOutput, SetRelation.EQUAL) {
			@Override
			public ExampleSetMetaData modifyExampleSet(ExampleSetMetaData metaData) throws UndefinedParameterError {
				metaData.setNumberOfExamples(getNumberOfExamplesFirst(metaData.getNumberOfExamples()));
				return super.modifyExampleSet(metaData);
			}
		});
		getTransformer().addRule(new ExampleSetPassThroughRule(exampleSetInput, secondNestedExampleSetOutput, SetRelation.EQUAL) {
			@Override
			public ExampleSetMetaData modifyExampleSet(ExampleSetMetaData metaData) throws UndefinedParameterError {
				metaData.setNumberOfExamples(getNumberOfExamplesSecond(metaData.getNumberOfExamples()));
				return super.modifyExampleSet(metaData);
			}
		});	

		getTransformer().addRule(new SubprocessTransformRule(getSubprocess(0)));
		getTransformer().addRule(firstToSecondExtender.makePassThroughRule());		
		getTransformer().addRule(new SubprocessTransformRule(getSubprocess(1)));
		getTransformer().addRule(secondToOutputExtender.makePassThroughRule());
	}

	protected abstract MDInteger getNumberOfExamplesFirst(MDInteger numberOfExamples) throws UndefinedParameterError;
	protected abstract MDInteger getNumberOfExamplesSecond(MDInteger numberOfExamples) throws UndefinedParameterError;

	/** Creates the splitted example set for this operator. Please note that the results must contain
	 *  two parts. */
	protected abstract SplittedExampleSet createSplittedExampleSet(ExampleSet exampleSet) throws OperatorException;

	@Override
	public void doWork() throws OperatorException {
		ExampleSet inputSet = exampleSetInput.getData();
		SplittedExampleSet exampleSet = createSplittedExampleSet(inputSet);
		// TODO: Simon: Clone?
		exampleSet.selectSingleSubset(0);
		firstNestedExampleSetOutput.deliver(exampleSet);
		getSubprocess(0).execute();

		exampleSet.selectSingleSubset(1);
		secondNestedExampleSetOutput.deliver(exampleSet);
		firstToSecondExtender.passDataThrough();
		getSubprocess(1).execute();

		secondToOutputExtender.passDataThrough();
	}

	protected InputPort getExampleSetInputPort() {
		return exampleSetInput;
	}
}