/*
 * eXist Open Source Native XML Database
 * Copyright (C) 2007-2009 The eXist Project
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *  
 *  $Id$
 */
package org.exist.xquery.modules.httpclient;

import org.apache.commons.httpclient.methods.HeadMethod;
import org.apache.log4j.Logger;

import org.exist.dom.QName;
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;

import java.io.IOException;

/**
 * @author Adam Retter <adam.retter@devon.gov.uk>
 * @author Andrzej Taramina <andrzej@chaeron.com>
 * @serial 20070905
 * @version 1.2
 */
public class HEADFunction extends BaseHTTPClientFunction {
    
	protected static final Logger logger = Logger.getLogger(HEADFunction.class);

	public final static FunctionSignature signature =
        new FunctionSignature(
        new QName( "head", NAMESPACE_URI, PREFIX ),
        "Performs a HTTP HEAD request."
        + " This method returns the HTTP response encoded as an XML fragment, that looks as follows: <httpclient:response  xmlns:httpclient=\"http://exist-db.org/xquery/httpclient\" statusCode=\"200\"><httpclient:headers><httpclient:header name=\"name\" value=\"value\"/>...</httpclient:headers></httpclient:response>",
        new SequenceType[] { URI_PARAM, PERSIST_PARAM, REQUEST_HEADER_PARAM },
        XML_BODY_RETURN 
        );
    
    
    public HEADFunction( XQueryContext context )
    {
        super( context, signature );
    }
    
    
    public Sequence eval( Sequence[] args, Sequence contextSequence ) throws XPathException
    {
        Sequence    response = null;
        
        // must be a URL
        if( args[0].isEmpty() ) {
            return( Sequence.EMPTY_SEQUENCE );
        }
        
        //get the url
        String url = args[0].itemAt( 0 ).getStringValue();
        //get the persist cookies
        boolean persistCookies = args[1].effectiveBooleanValue();
        
        //setup HEAD request
        HeadMethod head = new HeadMethod( url );
        
        //setup HEAD Request Headers
        if( !args[2].isEmpty() ) {
            setHeaders( head, ( (NodeValue)args[2].itemAt( 0 ) ).getNode() );
        }
        
        try {
            //execute the request
            response = doRequest( context, head, persistCookies );	
        }
        catch( IOException ioe ) {
            throw(new XPathException(this, ioe.getMessage(), ioe));
        }
        finally {
            head.releaseConnection();
        }
        
        return( response );
    }
}