/*
 *  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.filter;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.example.table.AttributeFactory;
import com.rapidminer.operator.OperatorDescription;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.ports.metadata.AttributeMetaData;
import com.rapidminer.operator.ports.metadata.ExampleSetMetaData;
import com.rapidminer.operator.ports.metadata.SetRelation;
import com.rapidminer.parameter.UndefinedParameterError;
import com.rapidminer.tools.Ontology;


/**
 * Converts all numerical attributes to nominal ones.
 * 
 * @author Ingo Mierswa
 */
public abstract class NumericToNominal extends AbstractFilteredDataProcessing {

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

	protected abstract void setValue(Example example, Attribute newAttribute, double value) throws OperatorException;

	/** Returns {@link Ontology#NOMINAL} or one of its subtypes. */
	protected abstract int getGeneratedAttributevalueType();

	protected Attribute makeAttribute() {
		return AttributeFactory.createAttribute(getGeneratedAttributevalueType());	
	}

	/** Will be invoked before the setValue method is invoked for each example. This
	 *  default implementation does nothing. */
	public void init() throws OperatorException {}

	/** Will be invoked after the setValue method was invoked for each example. This
	 *  default implementation does nothing. */
	public void cleanUp() throws OperatorException {}

	@Override
	public ExampleSetMetaData applyOnFilteredMetaData(ExampleSetMetaData emd) throws UndefinedParameterError {
		for (AttributeMetaData amd: emd.getAllAttributes()) {
			if (!amd.isSpecial() && amd.isNumerical()) {
				amd.setType(Ontology.NOMINAL);
				amd.setValueSetRelation(SetRelation.SUPERSET);
			}
		}
		return emd;
	}

	@Override
	public ExampleSet applyOnFiltered(ExampleSet exampleSet) throws OperatorException {        
		Map<Attribute, Attribute> translationMap = new LinkedHashMap<Attribute, Attribute>();
		// creating new nominal attributes
		for (Attribute originalAttribute : exampleSet.getAttributes()) {

			if (originalAttribute.isNumerical()) {
				Attribute newAttribute = makeAttribute();
				translationMap.put(originalAttribute, newAttribute);
			}
		}
		// adding to table and exampleSet
		for (Entry<Attribute, Attribute> replacement: translationMap.entrySet()) {
			Attribute newAttribute = replacement.getValue();
			exampleSet.getExampleTable().addAttribute(newAttribute);
			exampleSet.getAttributes().addRegular(newAttribute);
		}

		// invoke init
		init();

		// over all examples change attribute values
		for(Example example : exampleSet) {
			for(Entry<Attribute, Attribute> replacement: translationMap.entrySet()) {
				Attribute oldAttribute = replacement.getKey();
				Attribute newAttribute = replacement.getValue();
				double oldValue = example.getValue(oldAttribute);
				setValue(example, newAttribute, oldValue);
			}
			checkForStop();
		}

		// clean up
		cleanUp();

		// removing old attributes
		for (Map.Entry<Attribute,Attribute> entry : translationMap.entrySet()) {
			Attribute originalAttribute = entry.getKey();
			exampleSet.getAttributes().remove(originalAttribute);
			entry.getValue().setName(originalAttribute.getName());
		}

		return exampleSet;
	}
	
	/**
	 * This adds another column, does not modify existing.
	 */
	@Override
	public boolean writesIntoExistingData() {
		return false;
	}
	
	@Override
	protected int[] getFilterValueTypes() {
		return new int[] { Ontology.NUMERICAL };
	}
}