//
//  ========================================================================
//  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 java.util.concurrent.CountDownLatch;

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.LazyList;
import org.eclipse.jetty.util.MultiException;

/* ------------------------------------------------------------ */
/** A collection of handlers.  
 * <p>
 * The default implementations  calls all handlers in list order, 
 * regardless of the response status or exceptions. Derived implementation
 * may alter the order or the conditions of calling the contained 
 * handlers.
 * <p>
 * 
 * @org.apache.xbean.XBean
 */
public class HandlerCollection extends AbstractHandlerContainer
{
	private final boolean _mutableWhenRunning;
	private volatile Handler[] _handlers;
	private boolean _parallelStart=false; 

	/* ------------------------------------------------------------ */
	public HandlerCollection()
	{
		_mutableWhenRunning=false;
	}
	
	/* ------------------------------------------------------------ */
	public HandlerCollection(boolean mutableWhenRunning)
	{
		_mutableWhenRunning=mutableWhenRunning;
	}

	/* ------------------------------------------------------------ */
	/**
	 * @return Returns the handlers.
	 */
	public Handler[] getHandlers()
	{
		return _handlers;
	}
	
	/* ------------------------------------------------------------ */
	/**
	 * 
	 * @param handlers The handlers to set.
	 */
	public void setHandlers(Handler[] handlers)
	{
		if (!_mutableWhenRunning && isStarted())
			throw new IllegalStateException(STARTED);
		
		Handler [] old_handlers = _handlers==null?null:_handlers.clone();
		_handlers = handlers;
		
		Server server = getServer();
		MultiException mex = new MultiException();
		for (int i=0;handlers!=null && i<handlers.length;i++)
		{
			if (handlers[i].getServer()!=server)
				handlers[i].setServer(server);
		}

		// stop old handlers
		for (int i=0;old_handlers!=null && i<old_handlers.length;i++)
		{
			if (old_handlers[i]!=null)
			{
				try
				{
					if (old_handlers[i].isStarted())
						old_handlers[i].stop();
				}
				catch (Throwable e)
				{
					mex.add(e);
				}
			}
		}
				
		mex.ifExceptionThrowRuntime();
	}
	

	
	/* ------------------------------------------------------------ */
	/** Get the parrallelStart.
	 * @return true if the contained handlers are started in parallel.
	 */
	public boolean isParallelStart()
	{
		return _parallelStart;
	}



	/* ------------------------------------------------------------ */
	/** Set the parallelStart.
	 * @param parallelStart If true, contained handlers are started in parallel.
	 */
	public void setParallelStart(boolean parallelStart)
	{
		this._parallelStart = parallelStart;
	}

	@Override
	public void handle(String target, Request request, HttpServletResponse response) 
		throws IOException, ServletException
	{
		if (_handlers!=null && isStarted())
		{
			MultiException mex=null;
			
			for (int i=0;i<_handlers.length;i++)
			{
				try
				{
					_handlers[i].handle(target, request, response);
				}
				catch(IOException e)
				{
					throw e;
				}
				catch(RuntimeException e)
				{
					throw e;
				}
				catch(Exception e)
				{
					if (mex==null)
						mex=new MultiException();
					mex.add(e);
				}
			}
			if (mex!=null)
			{
				if (mex.size()==1)
					throw new ServletException(mex.getThrowable(0));
				else
					throw new ServletException(mex);
			}
			
		}    
	}

	/* ------------------------------------------------------------ */
	/* 
	 * @see org.eclipse.jetty.server.server.handler.AbstractHandler#doStart()
	 */
	@Override
	protected void doStart() throws Exception
	{
		final MultiException mex=new MultiException();
		if (_handlers!=null)
		{
			if (_parallelStart)
			{
				final CountDownLatch latch = new CountDownLatch(_handlers.length);
				final ClassLoader loader = Thread.currentThread().getContextClassLoader();
				for (int i=0;i<_handlers.length;i++)
				{
					final int h=i;
					getServer().threadPool.execute(
							new Runnable()
							{
								public void run()
								{
									ClassLoader orig = Thread.currentThread().getContextClassLoader();
									try
									{
										Thread.currentThread().setContextClassLoader(loader);
										_handlers[h].start();
									}
									catch(Throwable e)
									{
										mex.add(e);
									}
									finally
									{
										Thread.currentThread().setContextClassLoader(orig);
										latch.countDown();
									}
								}
							}
					);
				}
				latch.await();
			}
			else
			{
				for (int i=0;i<_handlers.length;i++)
				{
					try{_handlers[i].start();}
					catch(Throwable e){mex.add(e);}
				}
			}
		}
		super.doStart();
		mex.ifExceptionThrow();
	}

	/* ------------------------------------------------------------ */
	/* 
	 * @see org.eclipse.jetty.server.server.handler.AbstractHandler#doStop()
	 */
	@Override
	protected void doStop() throws Exception
	{
		MultiException mex=new MultiException();
		try { super.doStop(); } catch(Throwable e){mex.add(e);}
		if (_handlers!=null)
		{
			for (int i=_handlers.length;i-->0;)
				try{_handlers[i].stop();}catch(Throwable e){mex.add(e);}
		}
		mex.ifExceptionThrow();
	}
	
	/* ------------------------------------------------------------ */
	@Override
	public void setServer(Server server)
	{
		if (isStarted())
			throw new IllegalStateException(STARTED);
		
		Server old_server=getServer();
		
		super.setServer(server);

		Handler[] h=getHandlers();
		for (int i=0;h!=null && i<h.length;i++)
			h[i].setServer(server);
		
	}

	/* ------------------------------------------------------------ */
	/* Add a handler.
	 * This implementation adds the passed handler to the end of the existing collection of handlers. 
	 * @see org.eclipse.jetty.server.server.HandlerContainer#addHandler(org.eclipse.jetty.server.server.Handler)
	 */
	public void addHandler(Handler handler)
	{
		setHandlers((Handler[])LazyList.addToArray(getHandlers(), handler, Handler.class));
	}
	
	/* ------------------------------------------------------------ */
	public void removeHandler(Handler handler)
	{
		Handler[] handlers = getHandlers();
		
		if (handlers!=null && handlers.length>0 )
			setHandlers((Handler[])LazyList.removeFromArray(handlers, handler));
	}

	/* ------------------------------------------------------------ */
	@Override
	protected Object expandChildren(Object list, Class byClass)
	{
		Handler[] handlers = getHandlers();
		for (int i=0;handlers!=null && i<handlers.length;i++)
			list=expandHandler(handlers[i], list, byClass);
		return list;
	}

	/* ------------------------------------------------------------ */
	@Override
	public void destroy()
	{
		if (!isStopped())
			throw new IllegalStateException("!STOPPED");
		Handler[] children=getChildHandlers();
		setHandlers(null);
		for (Handler child: children)
			child.destroy();
		super.destroy();
	}
}