/*
 *  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.io;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.operator.OperatorDescription;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.UserError;
import com.rapidminer.parameter.ParameterType;
import com.rapidminer.parameter.ParameterTypeFile;
import com.rapidminer.tools.io.Encoding;


/**
 * Writes values of all examples into an ARFF file which can be used
 * by the machine learning library Weka. The ARFF format is described in the
 * {@link ArffExampleSource} operator which is able to read ARFF files to
 * make them usable with RapidMiner.
 * 
 * @rapidminer.index arff
 * @author Ingo Mierswa
 */
public class ArffExampleSetWriter extends AbstractExampleSetWriter {

    /** The parameter name for "File to save the example set to." */
    public static final String PARAMETER_EXAMPLE_SET_FILE = "example_set_file";

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

    @Override
    public ExampleSet write(ExampleSet exampleSet) throws OperatorException {
        try {
            File arffFile = getParameterAsFile(PARAMETER_EXAMPLE_SET_FILE, true);
            PrintWriter out = new PrintWriter(new OutputStreamWriter(new FileOutputStream(arffFile), Encoding.getEncoding(this)));
            writeArff(exampleSet, out);
            out.flush();
            out.close();
        } catch (IOException e) {
            throw new UserError(this, e, 303, new Object[] { getParameterAsString(PARAMETER_EXAMPLE_SET_FILE), e.getMessage() });
        }
        return exampleSet;
    }

    public static void writeArff(ExampleSet exampleSet, PrintWriter out) {
        // relation
        out.println("@RELATION RapidMinerData");
        out.println();

        // attribute meta data
        Iterator<Attribute> a = exampleSet.getAttributes().allAttributes();
        while (a.hasNext()) {
            printAttributeData(a.next(), out);
        }

        // data
        out.println();
        out.println("@DATA");

        for (Example example : exampleSet) {
            boolean first = true;
            a = exampleSet.getAttributes().allAttributes();
            while (a.hasNext()) {
                Attribute current = a.next();
                if (!first)
                    out.print(",");

                if (current.isNominal()) {
                    double value = example.getValue(current);
                    if (Double.isNaN(value))
                        out.print("?");
                    else
                        out.print("'" + example.getValueAsString(current) + "'");
                } else {
                    out.print(example.getValueAsString(current));
                }
                first = false;
            }
            out.println();
        }
    }

    private static void printAttributeData(Attribute attribute, PrintWriter out) {
        out.print("@ATTRIBUTE '" + attribute.getName() + "' ");
        if (attribute.isNominal()) {
            StringBuffer nominalValues = new StringBuffer("{");
            boolean first = true;
            for (String s : attribute.getMapping().getValues()) {
                if (!first)
                    nominalValues.append(",");
                nominalValues.append("'" + s + "'");
                first = false;
            }
            nominalValues.append("}");
            out.print(nominalValues.toString());
        } else {
            out.print("real");
        }
        out.println();
    }

    @Override
    protected boolean supportsEncoding() {
        return true;
    }

    @Override
    public List<ParameterType> getParameterTypes() {
        List<ParameterType> types = new LinkedList<ParameterType>();
        types.add(new ParameterTypeFile(PARAMETER_EXAMPLE_SET_FILE, "File to save the example set to.", "arff", false));
        types.addAll(super.getParameterTypes());
        return types;
    }
}