/*
 *  eXist Open Source Native XML Database
 *  Copyright (C) 2010 The eXist Project
 *  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.session;

import java.util.Date;

//import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.exist.dom.QName;
import org.exist.http.servlets.SessionWrapper;
import org.exist.xquery.*;
import org.exist.xquery.value.DateTimeValue;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.JavaObjectValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.Type;

/**
 * Returns the last time the client sent a request associated
 * with this session January 1, 1970 GMT if it is an invalidated
 * session
 * 
 * @author José María Fernández (jmfg@users.sourceforge.net)
 */
public class GetLastAccessedTime extends Function 
{
//	private static final Logger logger = LogManager.getLogger(GetAttribute.class);
	
	public final static FunctionSignature signature =
		new FunctionSignature(
			new QName( "get-last-accessed-time", SessionModule.NAMESPACE_URI, SessionModule.PREFIX ),
			"Returns the last time the client sent a request associated with this session. " +
			"If a session does not exist, a new one is created. Actions that your application " +
			"takes, such as getting or setting a value associated with the session, do not " +
			"affect the access time.  If the session is already invalidated, it returns " +
			"January 1, 1970 GMT",
			null,
			new FunctionReturnSequenceType(Type.DATE_TIME, Cardinality.EXACTLY_ONE, "the date-time when the session was last accessed" ) );
	
	public GetLastAccessedTime( XQueryContext context ) 
	{
		super( context, signature );
	}
	
	/* (non-Javadoc)
	 * @see org.exist.xquery.Expression#eval(org.exist.dom.persistent.DocumentSet, org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
	 */
	public Sequence eval( Sequence contextSequence, Item contextItem ) throws XPathException 
	{
		if (context.getProfiler().isEnabled()) {
			context.getProfiler().start(this);       
			context.getProfiler().message(this, Profiler.DEPENDENCIES, "DEPENDENCIES", Dependency.getDependenciesName(this.getDependencies()));
			if (contextSequence != null)
				{context.getProfiler().message(this, Profiler.START_SEQUENCES, "CONTEXT SEQUENCE", contextSequence);}
			if (contextItem != null)
				{context.getProfiler().message(this, Profiler.START_SEQUENCES, "CONTEXT ITEM", contextItem.toSequence());}
		}        
		
		final SessionModule myModule = (SessionModule)context.getModule(SessionModule.NAMESPACE_URI);
		
		// session object is read from global variable $session
		final Variable var = myModule.resolveVariable( SessionModule.SESSION_VAR );
		
		if( var == null || var.getValue() == null ) {
			// throw( new XPathException( this, "Session not set" ) );
			return( XPathUtil.javaObjectToXPath( Integer.valueOf(-1), context ) );
		}
		
		if( var.getValue().getItemType() != Type.JAVA_OBJECT ) {
			throw( new XPathException( this, ErrorCodes.XPDY0002, "Variable $session is not bound to a Java object." ) );
		}

		final JavaObjectValue session = (JavaObjectValue)var.getValue().itemAt( 0 );
		
		if( session.getObject() instanceof SessionWrapper ) {
			try {
				final long lastAccessedTime = ( (SessionWrapper)session.getObject() ).getLastAccessedTime();
				return new DateTimeValue(new Date(lastAccessedTime));
			}
			catch( final IllegalStateException ise ) {
				return new DateTimeValue(new Date(0));
			}
		} else {
			throw( new XPathException( this, ErrorCodes.XPDY0002, "Type error: variable $session is not bound to a session object" ) );
		}
	}
}