/*
 *  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.List;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.Attributes;
import com.rapidminer.example.ExampleSet;
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;
import com.rapidminer.parameter.ParameterTypeStringCategory;


/**
 * <p>
 * This operator can be used to change the attribute type of an attribute of the input example set.
 * If you want to change the attribute name you should use the {@link ChangeAttributeName} operator.
 * </p>
 *
 * <p>
 * The target type indicates if the attribute is a regular attribute (used by learning operators) or a
 * special attribute (e.g. a label or id attribute). The following target
 * attribute types are possible:
 * </p>
 * <ul>
 * <li>regular: only regular attributes are used as input variables for learning tasks</li>
 * <li>id: the id attribute for the example set</li>
 * <li>label: target attribute for learning</li>
 * <li>prediction: predicted attribute, i.e. the predictions of a learning scheme</li>
 * <li>cluster: indicates the memebership to a cluster</li>
 * <li>weight: indicates the weight of the example</li>
 * <li>batch: indicates the membership to an example batch</li>
 * </ul>
 * <p>
 * Users can also define own attribute types by simply using the desired name.
 * </p>
 * 
 * @author Ingo Mierswa
 * @version $Id: ChangeAttributeType.java,v 1.6 2008/07/07 07:06:40 ingomierswa Exp $
 */
public class ChangeAttributeType extends Operator {


	/** The parameter name for "The name of the attribute of which the type should be changed." */
	public static final String PARAMETER_NAME = "name";

	/** The parameter name for "The target type of the attribute (only changed if parameter change_attribute_type is true)." */
	public static final String PARAMETER_TARGET_TYPE = "target_type";
	private static final String REGULAR_NAME = "regular";

	private static final String[] TARGET_TYPES = new String[] { REGULAR_NAME, Attributes.ID_NAME, Attributes.LABEL_NAME, Attributes.PREDICTION_NAME, Attributes.CLUSTER_NAME, Attributes.WEIGHT_NAME, Attributes.BATCH_NAME };

	public ChangeAttributeType(OperatorDescription description) {
		super(description);
	}

	public IOObject[] apply() throws OperatorException {
		ExampleSet exampleSet = getInput(ExampleSet.class);
		String name = getParameterAsString(PARAMETER_NAME);
		Attribute attribute = exampleSet.getAttributes().get(name);
        
		if (attribute == null) {
			throw new UserError(this, 111, name);
		}

		exampleSet.getAttributes().remove(attribute);
		String newType = getParameterAsString(PARAMETER_TARGET_TYPE);
		if ((newType == null) || (newType.trim().length() == 0))
			throw new UserError(this, 201, new Object[] { "target_type", "change_attribute_type", "true" });
		if (newType.equals(REGULAR_NAME)) {
			exampleSet.getAttributes().addRegular(attribute);
		} else {
			exampleSet.getAttributes().setSpecialAttribute(attribute, newType);
		}

		return new IOObject[] { exampleSet };
	}

	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_NAME, "The name of the attribute of which the type should be changed.", false));
		ParameterType type = new ParameterTypeStringCategory(PARAMETER_TARGET_TYPE, "The target type of the attribute (only changed if parameter change_attribute_type is true).", TARGET_TYPES, TARGET_TYPES[0]);
		type.setExpert(false);
		types.add(type);
		return types;
	}
}