/**
 * Copyright 2007 DFKI GmbH.
 * All Rights Reserved.  Use is subject to license terms.
 *
 * This file is part of MARY TTS.
 *
 * MARY TTS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, version 3 of the License.
 *
 * 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
package marytts.modules;

import java.io.InputStream;

import marytts.datatypes.MaryData;
import marytts.datatypes.MaryDataType;
import marytts.datatypes.MaryXML;
import marytts.fst.FSTLookup;
import marytts.server.MaryProperties;
import marytts.util.MaryUtils;
import marytts.util.dom.MaryDomUtils;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.traversal.NodeIterator;
import org.w3c.dom.traversal.TreeWalker;

/**
 * Minimalistic part-of-speech tagger, using only function word tags as marked in the Transcription GUI.
 * 
 * @author Sathish Pammi
 * @author Marc Schröder
 */

public class MinimalisticPosTagger extends InternalModule {
	private String propertyPrefix;
	private FSTLookup posFST = null;
	private String punctuationList;

	/**
	 * Constructor which can be directly called from init info in the config file. Different languages can call this code with
	 * different settings.
	 * 
	 * @param locale
	 *            a locale string, e.g. "en"
	 * @param propertyPrefix
	 *            propertyPrefix
	 * @throws Exception
	 *             Exception
	 */
	public MinimalisticPosTagger(String locale, String propertyPrefix) throws Exception {
		super("OpenNLPPosTagger", MaryDataType.WORDS, MaryDataType.PARTSOFSPEECH, MaryUtils.string2locale(locale));
		if (!propertyPrefix.endsWith("."))
			propertyPrefix = propertyPrefix + ".";
		this.propertyPrefix = propertyPrefix + "partsofspeech.";
	}

	public void startup() throws Exception {
		super.startup();
		InputStream posFSTStream = MaryProperties.getStream(propertyPrefix + "fst");
		if (posFSTStream != null) {
			posFST = new FSTLookup(posFSTStream, MaryProperties.getProperty(propertyPrefix + "fst"));
		}
		punctuationList = MaryProperties.getProperty(propertyPrefix + "punctuation", ",.?!;");
	}

	public MaryData process(MaryData d) throws Exception {
		Document doc = d.getDocument();
		NodeIterator sentenceIt = MaryDomUtils.createNodeIterator(doc, doc, MaryXML.SENTENCE);
		Element sentence;
		while ((sentence = (Element) sentenceIt.nextNode()) != null) {
			TreeWalker tokenIt = MaryDomUtils.createTreeWalker(sentence, MaryXML.TOKEN);
			Element t;
			while ((t = (Element) tokenIt.nextNode()) != null) {
				String pos = "content";
				String tokenText = MaryDomUtils.tokenText(t);
				if (punctuationList.contains(tokenText)) {
					pos = "$PUNCT";
				} else if (posFST != null) {
					String[] result = posFST.lookup(tokenText);
					if (result.length != 0)
						pos = "function";
				}
				t.setAttribute("pos", pos);
			}
		}
		MaryData output = new MaryData(outputType(), d.getLocale());
		output.setDocument(doc);
		return output;
	}

}