//
//  ========================================================================
//  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.server.handler;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletResponse;

import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.util.component.LifeCycle;

/* ------------------------------------------------------------ */
/** A <code>HandlerWrapper</code> acts as a {@link Handler} but delegates the {@link Handler#handle handle} method and
 * {@link LifeCycle life cycle} events to a delegate. This is primarily used to implement the <i>Decorator</i> pattern.
 *
 */
public class HandlerWrapper extends AbstractHandlerContainer
{
	protected Handler _handler;

	/* ------------------------------------------------------------ */
	/**
	 *
	 */
	public HandlerWrapper()
	{
	}

	/* ------------------------------------------------------------ */
	/**
	 * @return Returns the handlers.
	 */
	public Handler getHandler()
	{
		return _handler;
	}

	/* ------------------------------------------------------------ */
	/**
	 * @return Returns the handlers.
	 */
	public Handler[] getHandlers()
	{
		if (_handler==null)
			return new Handler[0];
		return new Handler[] {_handler};
	}

	/* ------------------------------------------------------------ */
	/**
	 * @param handler Set the {@link Handler} which should be wrapped.
	 */
	public void setHandler(Handler handler)
	{
		if (isStarted())
			throw new IllegalStateException(STARTED);

		Handler old_handler = _handler;
		_handler = handler;
		if (handler!=null)
			handler.setServer(getServer());
	}

	/* ------------------------------------------------------------ */
	/*
	 * @see org.eclipse.thread.AbstractLifeCycle#doStart()
	 */
	@Override
	protected void doStart() throws Exception
	{
		if (_handler!=null)
			_handler.start();
		super.doStart();
	}

	/* ------------------------------------------------------------ */
	/*
	 * @see org.eclipse.thread.AbstractLifeCycle#doStop()
	 */
	@Override
	protected void doStop() throws Exception
	{
		if (_handler!=null)
			_handler.stop();
		super.doStop();
	}

	@Override
	public void handle(String target, Request request, HttpServletResponse response) throws IOException, ServletException
	{
		if (_handler!=null && isStarted())
		{
			_handler.handle(target, request, response);
		}
	}


	/* ------------------------------------------------------------ */
	@Override
	public void setServer(Server server)
	{
		Server old_server=getServer();
		if (server==old_server)
			return;

		if (isStarted())
			throw new IllegalStateException(STARTED);

		super.setServer(server);

		Handler h=getHandler();
		if (h!=null)
			h.setServer(server);
	}


	/* ------------------------------------------------------------ */
	@Override
	protected Object expandChildren(Object list, Class byClass)
	{
		return expandHandler(_handler,list,byClass);
	}

	/* ------------------------------------------------------------ */
	public <H extends Handler> H getNestedHandlerByClass(Class<H> byclass)
	{
		HandlerWrapper h=this;
		while (h!=null)
		{
			if (byclass.isInstance(h))
				return (H)h;
			Handler w = h.getHandler();
			if (w instanceof HandlerWrapper)
				h=(HandlerWrapper)w;
			else break;
		}
		return null;

	}

	/* ------------------------------------------------------------ */
	@Override
	public void destroy()
	{
		if (!isStopped())
			throw new IllegalStateException("!STOPPED");
		Handler child=getHandler();
		if (child!=null)
		{
			setHandler(null);
			child.destroy();
		}
		super.destroy();
	}

}