/*
 *  eXist Open Source Native XML Database
 *  Copyright (C) 2001-09 The eXist Team
 *
 *  http://exist-db.org
 *  
 *  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.util;

import org.apache.log4j.Logger;
import org.exist.dom.DocumentImpl;
import org.exist.dom.NodeProxy;
import org.exist.dom.QName;
import org.exist.memtree.NodeImpl;
import org.exist.numbering.NodeId;
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.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.NodeValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;

/**
 * @author wolf
 *
 */
public class GetNodeById extends BasicFunction {
	
	protected static final Logger logger = Logger.getLogger(GetNodeById.class);

	public final static FunctionSignature signature =
		new FunctionSignature(
			new QName("node-by-id", UtilModule.NAMESPACE_URI, UtilModule.PREFIX),
			"Retrieves a node by its internal node-id. The document is specified via the first " +
			"argument. It may either be a document node or another node from the same document " +
			"from which the target node will be retrieved by its id. The second argument is " +
			"the internal node-id, specified as a string. Please note: the function does " +
			"not check if the passed id does really point to an existing node. It just returns " +
			"a pointer, which may thus be invalid.",
			new SequenceType[] {
				new FunctionParameterSequenceType("document", Type.NODE, Cardinality.EXACTLY_ONE, "The document whose node is to be retrieved by its id"),
				new FunctionParameterSequenceType("node-id", Type.STRING, Cardinality.EXACTLY_ONE, "The internal node id")
			},
			new FunctionReturnSequenceType(Type.NODE, Cardinality.EXACTLY_ONE, "the node"));
	
	/**
	 * @param context
	 */
	public GetNodeById(XQueryContext context) {
		super(context, signature);
	}

	/* (non-Javadoc)
	 * @see org.exist.xquery.BasicFunction#eval(org.exist.xquery.value.Sequence[], org.exist.xquery.value.Sequence)
	 */
	public Sequence eval(Sequence[] args, Sequence contextSequence)
			throws XPathException {
		
        String id = args[1].itemAt(0).getStringValue();
        NodeId nodeId = context.getBroker().getBrokerPool().getNodeFactory().createFromString(id);
        NodeValue docNode = (NodeValue) args[0].itemAt(0);
        if (docNode.getImplementationType() == NodeValue.IN_MEMORY_NODE) {
            return ((NodeImpl) docNode).getDocument().getNodeById(nodeId);
        } else {
            DocumentImpl doc = ((NodeProxy)docNode).getDocument();
            return new NodeProxy(doc, nodeId);
        }
	}
}