/*
 * Copyright 2006 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package org.mortbay.jetty.gwt;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;

import com.google.gwt.user.server.rpc.UnexpectedException;

/**
 * Jetty Continuation support for GWT RPC.
 * 
 * @author Craig Day (craig@alderaan.com.au)
 */
public class AsyncRemoteServiceServlet extends OpenRemoteServiceServlet
{

	public static final String PAYLOAD = "com.google.gwt.payload";

	private static final String JETTY_RETRY_REQUEST_EXCEPTION = "org.mortbay.jetty.RetryRequest";

	/* ------------------------------------------------------------ */
	/*
	 * (non-Javadoc)
	 * 
	 * @see com.google.gwt.user.server.rpc.OpenRemoteServiceServlet#readPayloadAsUtf8(javax.servlet.http.HttpServletRequest)
	 */
	protected String readPayloadAsUtf8(HttpServletRequest request)
			throws IOException, ServletException
	{
		String payload = (String) request.getAttribute(PAYLOAD);
		if (payload == null)
		{
			payload = super.readPayloadAsUtf8(request);
			request.setAttribute(PAYLOAD, payload);
		}
		return payload;
	}

	/**
	 * Overridden to really throw Jetty RetryRequest Exception (as opposed to
	 * sending failure to client).
	 * 
	 * @param caught
	 *            the exception
	 */
	protected void doUnexpectedFailure(Throwable caught)
	{
		throwIfRetryRequest(caught);
		super.doUnexpectedFailure(caught);
	}

	/**
	 * Throws the Jetty RetryRequest if found.
	 * 
	 * @param caught
	 *            the exception
	 */
	protected void throwIfRetryRequest(Throwable caught)
	{
		if (caught instanceof UnexpectedException)
		{
			caught = caught.getCause();
		}
		if (caught instanceof ThreadDeath
				&& JETTY_RETRY_REQUEST_EXCEPTION.equals(caught.getClass()
						.getName()))
		{
			throw (Error) caught;
		}
	}

	/**
	 * return the request context for the current call
	 */
	protected RequestContext getRequestContext()
	{
		return new RequestContext(this.getThreadLocalRequest());
	}

}