/*
 *  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 org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.queryParser.QueryParser;
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.analysis.MpdlStandardAnalyzer;

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

	public final static FunctionSignature signature =
		new FunctionSignature(
			new QName("lucene-parse-query", MPDLTextModule.NAMESPACE_URI, MPDLTextModule.PREFIX),
			"A function which parses the given lucene query and returns an error message",
			new SequenceType[] { new SequenceType(Type.STRING, Cardinality.EXACTLY_ONE) },
			new SequenceType(Type.STRING, Cardinality.EXACTLY_ONE));

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

	public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
    String retMessage = "";
    ValueSequence result = new ValueSequence();
    Sequence luceneQueryStringSeq = args[0];
		if (luceneQueryStringSeq.isEmpty()) {
	    result.add(new StringValue(""));
			return result;
		}
		String luceneQueryString = luceneQueryStringSeq.getStringValue();
    if (luceneQueryString == null || luceneQueryString.equals("")) {
      result.add(new StringValue(""));
      return result;
    }
		try { 
      MpdlStandardAnalyzer analyzer = new MpdlStandardAnalyzer();
      QueryParser parser = new QueryParser("", analyzer);
      parser.parse(luceneQueryString);
    } catch (ParseException e) {
      retMessage = e.getMessage();
    }
    result.add(new StringValue(retMessage));
		return result;
	}
	
}