/*
 *  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.preprocessing.join;

import java.util.LinkedList;
import java.util.List;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.Attributes;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.example.set.MappedExampleSet;
import com.rapidminer.operator.OperatorDescription;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.UserError;
import com.rapidminer.operator.annotation.ResourceConsumptionEstimator;
import com.rapidminer.operator.ports.InputPort;
import com.rapidminer.operator.ports.metadata.ExampleSetMetaData;
import com.rapidminer.operator.ports.metadata.ExampleSetPrecondition;
import com.rapidminer.operator.ports.metadata.MetaData;
import com.rapidminer.operator.preprocessing.AbstractDataProcessing;
import com.rapidminer.parameter.UndefinedParameterError;
import com.rapidminer.tools.Ontology;
import com.rapidminer.tools.OperatorResourceConsumptionHandler;

/**
 * This operator performs a set intersection on two example sets, i.e., the
 * resulting example set contains all the examples of the first example set
 * whose IDs appear also in the second example set. As compared to SQL, both
 * example sets neither need to have neither the same number of columns nor the
 * same data types. The operation does only depend on the ID columns of the
 * example sets.
 * 
 * @author Tobias Malbrecht
 */
public class ExampleSetIntersect extends AbstractDataProcessing {

	private InputPort secondInput = getInputPorts().createPort("second");

	public ExampleSetIntersect(OperatorDescription description) {
		super(description);
		secondInput.addPrecondition(new ExampleSetPrecondition(secondInput, Ontology.ATTRIBUTE_VALUE, Attributes.ID_NAME));
	}

	@Override
	protected MetaData modifyMetaData(ExampleSetMetaData metaData) throws UndefinedParameterError {
		metaData.getNumberOfExamples().reduceByUnknownAmount();
		return metaData;
	}

	@Override
	public ExampleSet apply(ExampleSet exampleSet) throws OperatorException {
		ExampleSet secondSet = secondInput.getData();
		ExampleSet firstSet = exampleSet;

		secondSet.remapIds();
		firstSet.remapIds();

		Attribute firstId = firstSet.getAttributes().getId();
		Attribute secondId = secondSet.getAttributes().getId();

		// sanity checks
		if ((firstId == null) || (secondId == null)) {
			throw new UserError(this, 129);
		}
		if (firstId.getValueType() != secondId.getValueType()) {
			throw new UserError(this, 120, new Object[] { secondId.getName(), Ontology.VALUE_TYPE_NAMES[secondId.getValueType()], Ontology.VALUE_TYPE_NAMES[firstId.getValueType()] });
		}

		List<Integer> indices = new LinkedList<Integer>();
		{
			int i = 0;
			for (Example firstExample : firstSet) {
				double id = firstExample.getValue(firstId);
				Example secondExample = null;
				if (firstId.isNominal()) {
					secondExample = secondSet.getExampleFromId(secondId.getMapping().getIndex(firstId.getMapping().mapIndex((int) id))); 
				} else {
					secondExample = secondSet.getExampleFromId(id);
				}
				if (secondExample != null) {
					indices.add(i);
				}
				i++;
			}
		}

		int[] indexArray = new int[indices.size()];
		for (int i = 0; i < indices.size(); i++) {
			indexArray[i] = indices.get(i); 
		}

		return new MappedExampleSet(firstSet, indexArray);
	}
	
	@Override
	public boolean writesIntoExistingData() {
		return false;
	}
	
	@Override
	public ResourceConsumptionEstimator getResourceConsumptionEstimator() {
		return OperatorResourceConsumptionHandler.getResourceConsumptionEstimator(getInputPort(), ExampleSetIntersect.class, null);
	}

}