/*
 *  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 java.util.List;

import com.rapidminer.example.ExampleSet;
import com.rapidminer.operator.OperatorChain;
import com.rapidminer.operator.OperatorDescription;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.ValueDouble;
import com.rapidminer.operator.ports.CollectingPortPairExtender;
import com.rapidminer.operator.ports.InputPort;
import com.rapidminer.operator.ports.OutputPort;
import com.rapidminer.operator.ports.metadata.ExampleSetMetaData;
import com.rapidminer.operator.ports.metadata.MetaData;
import com.rapidminer.operator.ports.metadata.PassThroughRule;
import com.rapidminer.operator.ports.metadata.SubprocessTransformRule;
import com.rapidminer.parameter.ParameterType;
import com.rapidminer.parameter.ParameterTypeString;

/**
 * <p>This operator takes an input data set and applies its inner operators
 * as often as the number of examples of the input data is. Inner operators
 * can access the current example number (begins with 0) by a macro, whose name can be
 * specified via the parameter <code>iteration_macro</code>.</p>
 * 
 * <p>As input example will be used either the {@link ExampleSet} delivered on the
 * {@link OutputPort} of this operator or if not connected the initial unmodified 
 * {@link ExampleSet}.</p>
 * 
 * @author Marcin Skirzynski, Tobias Malbrecht
 */
public class ExampleIterator extends OperatorChain {

	public static final String PARAMETER_ITERATION_MACRO = "iteration_macro";
	public static final String DEFAULT_ITERATION_MACRO_NAME = "example";

	private final InputPort exampleSetInput = getInputPorts().createPort( "example set", ExampleSet.class );
	private final OutputPort exampleSetOutput = getOutputPorts().createPort( "example set" );
	private final OutputPort exampleSetInnerSource = getSubprocess(0).getInnerSources().createPort( "example set" );
	private final InputPort exampleSetInnerSink = getSubprocess(0).getInnerSinks().createPort( "example set" );
	private final CollectingPortPairExtender outExtender = new CollectingPortPairExtender("output", getSubprocess(0).getInnerSinks(), getOutputPorts());

	/**
	 * Indicates the current iteration respectively example.
	 */
	private int iteration;

	public ExampleIterator(OperatorDescription description) {
		super(description, "Example Process");
		outExtender.start();
		
		getTransformer().addPassThroughRule(exampleSetInput, exampleSetInnerSource);
		getTransformer().addRule( new SubprocessTransformRule(getSubprocess(0)) );
		getTransformer().addRule( new PassThroughRule(exampleSetInput, exampleSetOutput, false ) {
			@Override
			public MetaData modifyMetaData( MetaData unmodifiedMetaData ) {
				if ( exampleSetInnerSink.isConnected() ) {
					return exampleSetInnerSink.getMetaData();
				} else {
					// due to side effects, we cannot make any guarantee about the output.
					return new ExampleSetMetaData();
				}
			}
		});
		getTransformer().addRule(outExtender.makePassThroughRule());

		addValue(new ValueDouble( "iteration", "The number of the current iteration / loop / example." ) {
			@Override
			public double getDoubleValue() {
				return iteration;
			}
		});

	}

	/**
	 * Gets the input data and macro name and iterates over the example set while updating
	 * the current iteration in the given macro.
	 */
	@Override
	public void doWork() throws OperatorException {
		outExtender.reset();
		ExampleSet exampleSet = exampleSetInput.getData();
		String iterationMacroName = getParameterAsString( PARAMETER_ITERATION_MACRO );
		boolean innerSinkIsConnected = exampleSetInnerSink.isConnected();

		for (iteration = 1; iteration <= exampleSet.size(); iteration++ ) {

			getProcess().getMacroHandler().addMacro( iterationMacroName, String.valueOf( iteration ) );

			// passing in clone or if connected the result from last iteration
			exampleSetInnerSource.deliver( innerSinkIsConnected ? exampleSet : (ExampleSet) exampleSet.clone());
			getSubprocess(0).execute();
			inApplyLoop();

			if( innerSinkIsConnected ) {
				exampleSet = exampleSetInnerSink.getData();
			}

			outExtender.collect();
		}

		getProcess().getMacroHandler().removeMacro( iterationMacroName );
		exampleSetOutput.deliver(exampleSet);
	}

	/**
	 * Provides the iteration macro name.
	 */
	@Override
	public List<ParameterType> getParameterTypes() {
		List<ParameterType> types = super.getParameterTypes();
		types.add( new ParameterTypeString( PARAMETER_ITERATION_MACRO, "The name of the macro which holds the index of the current example in each iteration.", DEFAULT_ITERATION_MACRO_NAME, false ) );
		return types;
	}
}