/*
 *  eXist Open Source Native XML Database
 *  Copyright (C) 2001-09 Wolfgang M. Meier
 *  wolfgang@exist-db.org
 *  http://exist.sourceforge.net
 *
 *  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.
 *
 *  $Id$
 */
package org.exist.xquery.functions.system;

import java.nio.file.Path;
import java.util.Optional;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
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.FunctionReturnSequenceType;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.StringValue;
import org.exist.xquery.value.Type;

/**
 * Return the eXist home.
 *
 * @author Dannes Wessels
 */
public class GetExistHome extends BasicFunction {
    
    protected final static Logger logger = LogManager.getLogger(GetExistHome.class);

    public final static FunctionSignature signature =
            new FunctionSignature(
            new QName("get-exist-home", SystemModule.NAMESPACE_URI, SystemModule.PREFIX),
            "Returns the eXist home location.",
            FunctionSignature.NO_ARGS,
            new FunctionReturnSequenceType(Type.STRING, Cardinality.EXACTLY_ONE, "the path to the eXist home"));
    
    public GetExistHome(XQueryContext context) {
        super(context, signature);
    }

    @Override
    public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
        final Optional<Path> existHome = context.getBroker().getConfiguration().getExistHome();
        return existHome.<Sequence>map(h -> new StringValue(h.toAbsolutePath().toString())).orElse(Sequence.EMPTY_SEQUENCE);
    }
}