/*
 *  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.learner.weka;

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

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.tools.WekaInstancesAdaptor;
import com.rapidminer.tools.WekaTools;

import weka.associations.Associator;
import weka.core.Instances;
import weka.core.OptionHandler;
import weka.core.TechnicalInformation;
import weka.core.TechnicalInformationHandler;

/**
 * Performs the Weka association rule learner with the same name. The operator
 * returns a result object containing the rules found by the association
 * learner. In contrast to models generated by normal learners, the association
 * rules cannot be applied to an example set. Hence, there is no way to evaluate
 * the performance of association rules yet. See the Weka javadoc for further
 * operator and parameter descriptions.
 * 
 * @author Ingo Mierswa
 * @version $Id: GenericWekaAssociationLearner.java,v 1.17 2006/04/05 09:42:01
 *          ingomierswa Exp $
 */
public class GenericWekaAssociationLearner extends Operator implements TechnicalInformationHandler {

	public static final String[] WEKA_ASSOCIATORS = WekaTools.getWekaClasses(weka.associations.Associator.class);

	/** The list with the weka parameters. */
	private List<ParameterType> wekaParameters = new LinkedList<ParameterType>();

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

	public IOObject[] apply() throws OperatorException {
		ExampleSet exampleSet = getInput(ExampleSet.class);
		Associator associator = getWekaAssociator(getOperatorClassName(), WekaTools.getWekaParametersFromTypes(this, wekaParameters));

		log("Converting to Weka instances.");
		Instances instances = WekaTools.toWekaInstances(exampleSet, "MiningInstances", WekaInstancesAdaptor.ASSOCIATION_RULE_MINING);
		try {
			log("Building Weka associator.");
			associator.buildAssociations(instances);
		} catch (Exception e) {
			throw new UserError(this, e, 905, new Object[] { getOperatorClassName(), e });
		}
		return new IOObject[] { new WekaAssociator(getOperatorClassName(), associator) };
	}

	/** Returns the Weka associator based on the subtype of this operator. */
	private Associator getWekaAssociator(String prefixName, String[] parameters) throws OperatorException {
		String actualName = prefixName.substring(WekaTools.WEKA_OPERATOR_PREFIX.length());
		String associatorName = null;
		for (int i = 0; i < WEKA_ASSOCIATORS.length; i++) {
			if (WEKA_ASSOCIATORS[i].endsWith(actualName)) {
				associatorName = WEKA_ASSOCIATORS[i];
				break;
			}
		}
		Associator associator = null;
		try {
			Class clazz = Class.forName(associatorName);
			associator = (Associator) clazz.newInstance();
			if (associator instanceof OptionHandler) {
				OptionHandler optionHandler = (OptionHandler)associator;
				optionHandler.setOptions(parameters);
			}
		} catch (Exception e) {
			throw new UserError(this, e, 904, new Object[] { associatorName, e });
		}
		return associator;
	}

	public TechnicalInformation getTechnicalInformation() {
		try {
			Associator associator = getWekaAssociator(getOperatorClassName(), null);
			if (associator instanceof TechnicalInformationHandler)
				return ((TechnicalInformationHandler)associator).getTechnicalInformation();
			else
				return null;
		} catch (OperatorException e) {
			return null;
		}
	}
	
	public Class<?>[] getInputClasses() {
		return new Class[] { ExampleSet.class };
	}

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

	public List<ParameterType> getParameterTypes() {
		List<ParameterType> types = super.getParameterTypes();

		Associator associator = null;
		try {
			// parameters must be null, not an empty String[0] array!
			associator = getWekaAssociator(getOperatorClassName(), null);
		} catch (OperatorException e) {
			throw new RuntimeException("Cannot instantiate Weka associator " + getOperatorClassName());
		}
		wekaParameters = new LinkedList<ParameterType>();
		if ((associator != null) && (associator instanceof OptionHandler)) {
			WekaTools.addParameterTypes((OptionHandler) associator, types, wekaParameters, false, null);
		}
		return types;
	}
}