/*
 *  eXist Open Source Native XML Database: Extension module
 *  Copyright (C) 2008 Josef Willenborg
 *  jwillenborg@mpiwg-berlin.mpg.de
 *  http://www.mpiwg-berlin.mpg.de
 *  
 *  This program 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; either version 2
 *  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 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, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *  
 *  $Id: TextModule.java $
 */
package org.exist.xquery.modules.mpdltext;

import java.util.ArrayList;

import org.exist.dom.QName;
import org.exist.xquery.BasicFunction;
import org.exist.xquery.Cardinality;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.StringValue;
import org.exist.xquery.value.Type;
import org.exist.xquery.value.ValueSequence;

import de.mpg.mpiwg.berlin.mpdl.donatus.xmlrpc.DonatusCache;
import de.mpg.mpiwg.berlin.mpdl.donatus.xmlrpc.DonatusVariant;
import de.mpg.mpiwg.berlin.mpdl.exception.ApplicationException;

/**
 * @author Josef Willenborg (jwillenborg@mpiwg-berlin.mpg.de)
 */
public class GetDonatusQueryVariants extends BasicFunction {

	public final static FunctionSignature signature =
		new FunctionSignature(
			new QName("get-donatus-query-variants", MPDLTextModule.NAMESPACE_URI, MPDLTextModule.PREFIX),
			"A function which delivers morphological variants (seperated by |) of a given Lucene query string of a given " +
			"language over the lemma of that variant by the Donatus language technology",
			new SequenceType[] { new SequenceType(Type.STRING, Cardinality.ZERO_OR_MORE), 
			                     new SequenceType(Type.STRING, Cardinality.ZERO_OR_MORE) },
			new SequenceType(Type.STRING, Cardinality.ZERO_OR_MORE));

	public GetDonatusQueryVariants(XQueryContext context) {
		super(context, signature);
	}

	public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
	  Sequence langSeq = args[0];
    Sequence luceneQueryStringSeq = args[1];
    String language = "";
    String luceneQueryString = "";
		if (langSeq.isEmpty() || luceneQueryStringSeq.isEmpty())
			return Sequence.EMPTY_SEQUENCE;
		language = langSeq.getStringValue();
		luceneQueryString = luceneQueryStringSeq.getStringValue();
		ArrayList<DonatusVariant> resultVariants = null;
		try { 
	    DonatusCache donatusCache = DonatusCache.getInstance();
	    resultVariants = donatusCache.getQueryVariants(language, luceneQueryString);
    } catch (ApplicationException e) {
      throw new XPathException(e);
    }
    ValueSequence result = new ValueSequence();
    String resultStr = "";
    int size = resultVariants.size();
    for (int i=0; i<size; i++) {
      String variantStr = resultVariants.get(i).getForm();
      resultStr = resultStr + variantStr + "|";
    }
    if (size == 0) {
      result.add(new StringValue(""));
    } else {
      resultStr = resultStr.substring(0, resultStr.length() - 1); // without last | character
      result.add(new StringValue(resultStr));
    }
		return result;
	}
}