/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2008 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.filter;

import java.util.Iterator;
import java.util.List;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.example.table.AttributeFactory;
import com.rapidminer.example.table.NominalMapping;
import com.rapidminer.operator.IOObject;
import com.rapidminer.operator.Operator;
import com.rapidminer.operator.OperatorDescription;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.UserError;
import com.rapidminer.parameter.ParameterType;
import com.rapidminer.parameter.ParameterTypeString;


/**
 * Merges two nominal values of a given attribute.
 * 
 * @author Ingo Mierswa
 * @version $Id: MergeNominalValues.java,v 1.10 2006/04/05 08:57:27 ingomierswa
 *          Exp $
 */
public class MergeNominalValues extends Operator {

	/** The parameter name for "The name of the nominal attribute which values should be merged." */
	public static final String PARAMETER_ATTRIBUTE_NAME = "attribute_name";

	/** The parameter name for "The first value which should be merged." */
	public static final String PARAMETER_FIRST_VALUE = "first_value";

	/** The parameter name for "The second value which should be merged." */
	public static final String PARAMETER_SECOND_VALUE = "second_value";
	
	public MergeNominalValues(OperatorDescription description) {
		super(description);
	}

	public IOObject[] apply() throws OperatorException {
		ExampleSet exampleSet = getInput(ExampleSet.class);

		String name = getParameterAsString(PARAMETER_ATTRIBUTE_NAME);
		Attribute attribute = null;
		for (Attribute current : exampleSet.getAttributes()) {
			if (current.getName().equals(name)) {
				if (!current.isNominal())
					throw new UserError(this, 119, new Object[] { name, this.getName() });
				attribute = current;
				break;
			}
		}

		if (attribute == null) {
			throw new UserError(this, 111, name);
		} else {
			String firstValue = getParameterAsString(PARAMETER_FIRST_VALUE);
			String secondValue = getParameterAsString(PARAMETER_SECOND_VALUE);
			mergeValues(exampleSet, attribute, firstValue, secondValue);
		}

		return new IOObject[] { exampleSet };
	}

	private void mergeValues(ExampleSet exampleSet, Attribute attribute, String firstValue, String secondValue) 
	    throws OperatorException {
		Attribute newAttribute = AttributeFactory.createAttribute(attribute, "merged");
		// clone is necessary here!
		NominalMapping mapping = (NominalMapping)attribute.getMapping().clone();
		mapping.clear();
		newAttribute.setMapping(mapping);
		
		exampleSet.getExampleTable().addAttribute(newAttribute);
		exampleSet.getAttributes().addRegular(newAttribute);

		double first = attribute.getMapping().mapString(firstValue);
		double second = attribute.getMapping().mapString(secondValue);
		String firstPlusSecondString = firstValue + "_" + secondValue;
		Iterator<Example> reader = exampleSet.iterator();
		while (reader.hasNext()) {
			Example example = reader.next();
			double value = example.getValue(attribute);
			if (Double.isNaN(value)) {
				example.setValue(newAttribute, Double.NaN);
			} else if ((value == first) || (value == second))
				example.setValue(newAttribute, newAttribute.getMapping().mapString(firstPlusSecondString));
			else
				example.setValue(newAttribute, newAttribute.getMapping().mapString(attribute.getMapping().mapIndex((int) value)));
			checkForStop();
		}
		exampleSet.getAttributes().remove(attribute);
		newAttribute.setName(attribute.getName());
	}

	public Class<?>[] getInputClasses() {
		return new Class[] { ExampleSet.class };
	}

	public Class<?>[] getOutputClasses() {
		return new Class[] { ExampleSet.class };
	}

	public List<ParameterType> getParameterTypes() {
		List<ParameterType> types = super.getParameterTypes();
		types.add(new ParameterTypeString(PARAMETER_ATTRIBUTE_NAME, "The name of the nominal attribute which values should be merged.", false));
		types.add(new ParameterTypeString(PARAMETER_FIRST_VALUE, "The first value which should be merged.", false));
		types.add(new ParameterTypeString(PARAMETER_SECOND_VALUE, "The second value which should be merged.", false));
		return types;
	}
}