//
   //  ========================================================================
   //  Copyright (c) 1995-2013 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.continuation;
  
  import java.lang.reflect.Constructor;
  
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletRequestWrapper;
  import javax.servlet.ServletResponse;
  
  /* ------------------------------------------------------------ */
  /** ContinuationSupport.
   *
   * Factory class for accessing Continuation instances, which with either be
   * native to the container (jetty >= 6), a servlet 3.0 or a faux continuation.
   *
   */
  public class ContinuationSupport
  {
      static final boolean __jetty6;
      static final boolean __servlet3;
      static final Class<?> __waitingContinuation;
      static final Constructor<? extends Continuation> __newServlet3Continuation;
      static final Constructor<? extends Continuation> __newJetty6Continuation;
      static
      {
          boolean servlet3Support=false;
          Constructor<? extends Continuation>s3cc=null;
          try
          {
              boolean servlet3=ServletRequest.class.getMethod("startAsync")!=null;
              if (servlet3)
              {
                  Class<? extends Continuation> s3c = ContinuationSupport.class.getClassLoader().loadClass("org.eclipse.jetty.continuation.Servlet3Continuation").asSubclass(Continuation.class);
                  s3cc=s3c.getConstructor(ServletRequest.class);
                  servlet3Support=true;
              }
          }
          catch (Exception e)
          {}
          finally
          {
              __servlet3=servlet3Support;
              __newServlet3Continuation=s3cc;
          }
          
          boolean jetty6Support=false;
          Constructor<? extends Continuation>j6cc=null;
          try
          {
              Class<?> jetty6ContinuationClass = ContinuationSupport.class.getClassLoader().loadClass("org.mortbay.util.ajax.Continuation");
              boolean jetty6=jetty6ContinuationClass!=null;
              if (jetty6)
              {
                  Class<? extends Continuation> j6c = ContinuationSupport.class.getClassLoader().loadClass("org.eclipse.jetty.continuation.Jetty6Continuation").asSubclass(Continuation.class);
                  j6cc=j6c.getConstructor(ServletRequest.class, jetty6ContinuationClass);
                  jetty6Support=true;
              }
          }
          catch (Exception e)
          {}
          finally
          {
              __jetty6=jetty6Support;
              __newJetty6Continuation=j6cc;
          }
          
          Class<?> waiting=null;
          try
          {
              waiting=ContinuationSupport.class.getClassLoader().loadClass("org.mortbay.util.ajax.WaitingContinuation");
          }
          catch (Exception e)
          {
          }
          finally
          {
              __waitingContinuation=waiting;
          }
      }
  
      /* ------------------------------------------------------------ */
      /**
      * Get a Continuation.  The type of the Continuation returned may
      * vary depending on the container in which the application is 
      * deployed. It may be an implementation native to the container (eg
      * org.eclipse.jetty.server.AsyncContinuation) or one of the utility
      * implementations provided such as an internal <code>FauxContinuation</code>
      * or a real implementation like {@link org.eclipse.jetty.continuation.Servlet3Continuation}.
      * @param request The request 
      * @return a Continuation instance
      */
     public static Continuation getContinuation(ServletRequest request)
     {
         Continuation continuation = (Continuation) request.getAttribute(Continuation.ATTRIBUTE);
         if (continuation!=null)
             return continuation;
         
         while (request instanceof ServletRequestWrapper)
             request=((ServletRequestWrapper)request).getRequest();
         
         if (__servlet3 )
         {
             try
             {
                 continuation=__newServlet3Continuation.newInstance(request);
                 request.setAttribute(Continuation.ATTRIBUTE,continuation);
                 return continuation;
             }
             catch(Exception e)
             {
                 throw new RuntimeException(e);
             }
         }
 
         if (__jetty6)
         {
             Object c=request.getAttribute("org.mortbay.jetty.ajax.Continuation");
             try
             {
                 if (c==null || __waitingContinuation==null || __waitingContinuation.isInstance(c))
                     continuation=new FauxContinuation(request);
                 else
                     continuation= __newJetty6Continuation.newInstance(request,c);
                 request.setAttribute(Continuation.ATTRIBUTE,continuation);
                 return continuation;
             }
             catch(Exception e)
             {
                 throw new RuntimeException(e);
             }
         }
 
         throw new IllegalStateException("!(Jetty || Servlet 3.0 || ContinuationFilter)");
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param request the servlet request
      * @param response the servlet response
      * @deprecated use {@link #getContinuation(ServletRequest)}
      * @return the continuation
      */
     @Deprecated
     public static Continuation getContinuation(final ServletRequest request, final ServletResponse response)
     {
         return getContinuation(request);
     }
 }