/*
 *  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.io;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;

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.operator.postprocessing.Threshold;
import com.rapidminer.parameter.ParameterType;
import com.rapidminer.parameter.ParameterTypeFile;


/**
 * Reads a threshold from a file. The first line must hold the threshold, the
 * second the value of the first class, and the second the value of the second
 * class. This file can be written in another process using the
 * {@link ThresholdWriter}.
 * 
 * @author Ingo Mierswa
 * @version $Id: ThresholdLoader.java,v 1.6 2008/07/07 07:06:38 ingomierswa Exp $
 */
public class ThresholdLoader extends Operator {


	/** The parameter name for "Filename for the threshold file." */
	public static final String PARAMETER_THRESHOLD_FILE = "threshold_file";
	public ThresholdLoader(OperatorDescription description) {
		super(description);
	}

	/** Loads the threshold from a file. */
	public IOObject[] apply() throws OperatorException {
		File thresholdFile = getParameterAsFile(PARAMETER_THRESHOLD_FILE);
		Threshold threshold = null;
		try {
			InputStream in = new FileInputStream(thresholdFile);
            Document document = null;
            try {
                document = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(in);
            } catch (SAXException e1) {
                throw new IOException(e1.getMessage());
            } catch (ParserConfigurationException e1) {
                throw new IOException(e1.getMessage());
            }

            Element thresholdElement = document.getDocumentElement();
            if (!thresholdElement.getTagName().equals("threshold")) {
                throw new IOException("Outer tag of threshold file must be <threshold>");
            }
            
            String thresholdValueString = thresholdElement.getAttribute("value");
            String thresholdFirst = thresholdElement.getAttribute("first");
            String thresholdSecond = thresholdElement.getAttribute("second");
            double thresholdValue = Double.parseDouble(thresholdValueString);
            threshold = new Threshold(thresholdValue, thresholdFirst, thresholdSecond);
			in.close();
		} catch (IOException e) {
			throw new UserError(this, e, 303, new Object[] { thresholdFile, e.getMessage() });
		}

		return new IOObject[] { threshold };
	}

	public Class<?>[] getInputClasses() {
		return new Class[0];
	}

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

	public List<ParameterType> getParameterTypes() {
		List<ParameterType> types = super.getParameterTypes();
		types.add(new ParameterTypeFile(PARAMETER_THRESHOLD_FILE, "Filename for the threshold file.", "thr", false));
		return types;
	}
}