// ========================================================================
   // Copyright (c) 1999-2009 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.servlet;
  
  import java.io.IOException;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Stack;
  
  import javax.servlet.Servlet;
  import javax.servlet.ServletConfig;
  import javax.servlet.ServletException;
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.SingleThreadModel;
  import javax.servlet.UnavailableException;
  
  import org.eclipse.jetty.security.IdentityService;
  import org.eclipse.jetty.security.RunAsToken;
  import org.eclipse.jetty.server.Request;
  import org.eclipse.jetty.server.UserIdentity;
  import org.eclipse.jetty.util.log.Log;
  
  
  
  
  /* --------------------------------------------------------------------- */
  /** Servlet Instance and Context Holder.
   * Holds the name, params and some state of a javax.servlet.Servlet
   * instance. It implements the ServletConfig interface.
   * This class will organise the loading of the servlet when needed or
   * requested.
   *
   * 
   */
  public class ServletHolder extends Holder implements UserIdentity.Scope, Comparable
  {
      /* ---------------------------------------------------------------- */
      private int _initOrder;
      private boolean _initOnStartup=false;
      private Map<String, String> _roleMap;
      private String _forcedPath;
      private String _runAsRole;
      private RunAsToken _runAsToken;
      private IdentityService _identityService;
      
      
      private transient Servlet _servlet;
      private transient Config _config;
      private transient long _unavailable;
      private transient UnavailableException _unavailableEx;
      public static final Map<String,String> NO_MAPPED_ROLES = Collections.emptyMap();
  
      /* ---------------------------------------------------------------- */
      /** Constructor .
       */
      public ServletHolder()
      {}
      
      /* ---------------------------------------------------------------- */
      /** Constructor for existing servlet.
       */
      public ServletHolder(Servlet servlet)
      {
          setServlet(servlet);
      }
  
      /* ---------------------------------------------------------------- */
      /** Constructor for existing servlet.
       */
      public ServletHolder(Class servlet)
      {
          super(servlet);
      }
  
      /* ---------------------------------------------------------------- */
      /**
       * @return The unavailable exception or null if not unavailable
       */
      public UnavailableException getUnavailableException()
      {
          return _unavailableEx;
      }
      
      /* ------------------------------------------------------------ */
      public synchronized void setServlet(Servlet servlet)
      {
         if (servlet==null || servlet instanceof SingleThreadModel)
             throw new IllegalArgumentException();
 
         _extInstance=true;
         _servlet=servlet;
         setHeldClass(servlet.getClass());
         if (getName()==null)
             setName(servlet.getClass().getName()+"-"+super.hashCode());
     }
     
     /* ------------------------------------------------------------ */
     public int getInitOrder()
     {
         return _initOrder;
     }
 
     /* ------------------------------------------------------------ */
     /** Set the initialize order.
      * Holders with order<0, are initialized on use. Those with
      * order>=0 are initialized in increasing order when the handler
      * is started.
      */
     public void setInitOrder(int order)
     {
         _initOnStartup=true;
         _initOrder = order;
     }
 
     /* ------------------------------------------------------------ */
     /** Comparitor by init order.
      */
     public int compareTo(Object o)
     {
         if (o instanceof ServletHolder)
         {
             ServletHolder sh= (ServletHolder)o;
             if (sh==this)
                 return 0;
             if (sh._initOrder<_initOrder)
                 return 1;
             if (sh._initOrder>_initOrder)
                 return -1;
             
             int c=(_className!=null && sh._className!=null)?_className.compareTo(sh._className):0;
             if (c==0)
                 c=_name.compareTo(sh._name);
             if (c==0)
                 c=this.hashCode()>o.hashCode()?1:-1;
             return c;
         }
         return 1;
     }
 
     /* ------------------------------------------------------------ */
     public boolean equals(Object o)
     {
         return compareTo(o)==0;
     }
 
     /* ------------------------------------------------------------ */
     public int hashCode()
     {
         return _name==null?System.identityHashCode(this):_name.hashCode();
     }
 
     /* ------------------------------------------------------------ */
     /** Link a user role.
      * Translate the role name used by a servlet, to the link name
      * used by the container.
      * @param name The role name as used by the servlet
      * @param link The role name as used by the container.
      */
     public synchronized void setUserRoleLink(String name,String link)
     {
         if (_roleMap==null)
             _roleMap=new HashMap<String, String>();
         _roleMap.put(name,link);
     }
     
     /* ------------------------------------------------------------ */
     /** get a user role link.
      * @param name The name of the role
      * @return The name as translated by the link. If no link exists,
      * the name is returned.
      */
     public String getUserRoleLink(String name)
     {
         if (_roleMap==null)
             return name;
         String link= _roleMap.get(name);
         return (link==null)?name:link;
     }
 
     /* ------------------------------------------------------------ */
     public Map<String, String> getRoleMap()
     {
         return _roleMap == null? NO_MAPPED_ROLES : _roleMap;
     }
     
     /* ------------------------------------------------------------ */
     /**
      * @return Returns the forcedPath.
      */
     public String getForcedPath()
     {
         return _forcedPath;
     }
     
     /* ------------------------------------------------------------ */
     /**
      * @param forcedPath The forcedPath to set.
      */
     public void setForcedPath(String forcedPath)
     {
         _forcedPath = forcedPath;
     }
     
     /* ------------------------------------------------------------ */
     public void doStart()
         throws Exception
     {
         _unavailable=0;
         try
         {
             super.doStart();
             checkServletType();
         }
         catch (UnavailableException ue)
         {
             makeUnavailable(ue);
         }
 
         _identityService = _servletHandler.getIdentityService();
         if (_identityService!=null && _runAsRole!=null)
             _runAsToken=_identityService.newRunAsToken(_runAsRole);
         
         _config=new Config();
 
         if (_class!=null && javax.servlet.SingleThreadModel.class.isAssignableFrom(_class))
             _servlet = new SingleThreadedWrapper();
 
         if (_extInstance || _initOnStartup)
         {
             try
             {
                 initServlet();
             }
             catch(Exception e)
             {
                 if (_servletHandler.isStartWithUnavailable())
                     Log.ignore(e);
                 else
                     throw e;
             }
         }  
     }
 
     /* ------------------------------------------------------------ */
     public void doStop()
         throws Exception
     {
         Object old_run_as = null;
         if (_servlet!=null)
         {       
             try
             {
                 if (_identityService!=null)
                     old_run_as=_identityService.setRunAs(_identityService.getSystemUserIdentity(),_runAsToken);
 
                 destroyInstance(_servlet);
             }
             catch (Exception e)
             {
                 Log.warn(e);
             }
             finally
             {
                 if (_identityService!=null)
                     _identityService.unsetRunAs(old_run_as);
             }
         }
 
         if (!_extInstance)
             _servlet=null;
 
         _config=null;
     }
 
     /* ------------------------------------------------------------ */
     public void destroyInstance (Object o)
     throws Exception
     {
         if (o==null)
             return;
         Servlet servlet =  ((Servlet)o);
         servlet.destroy();
         getServletHandler().customizeServletDestroy(servlet);
     }
 
     /* ------------------------------------------------------------ */
     /** Get the servlet.
      * @return The servlet
      */
     public synchronized Servlet getServlet()
         throws ServletException
     {
         // Handle previous unavailability
         if (_unavailable!=0)
         {
             if (_unavailable<0 || _unavailable>0 && System.currentTimeMillis()<_unavailable)
                 throw _unavailableEx;
             _unavailable=0;
             _unavailableEx=null;
         }
 
         if (_servlet==null)
             initServlet();
         return _servlet;
     }
 
     /* ------------------------------------------------------------ */
     /** Get the servlet instance (no initialization done).
      * @return The servlet or null
      */
     public Servlet getServletInstance()
     {
         return _servlet;
     }
         
     /* ------------------------------------------------------------ */
     /**
      * Check to ensure class of servlet is acceptable.
      * @throws UnavailableException
      */
     public void checkServletType ()
         throws UnavailableException
     {
         if (_class==null || !javax.servlet.Servlet.class.isAssignableFrom(_class))
         {
             throw new UnavailableException("Servlet "+_class+" is not a javax.servlet.Servlet");
         }
     }
 
     /* ------------------------------------------------------------ */
     /** 
      * @return true if the holder is started and is not unavailable
      */
     public boolean isAvailable()
     {
         if (isStarted()&& _unavailable==0)
             return true;
         try 
         {
             getServlet();
         }
         catch(Exception e)
         {
             Log.ignore(e);
         }
 
         return isStarted()&& _unavailable==0;
     }
     
     /* ------------------------------------------------------------ */
     private void makeUnavailable(UnavailableException e)
     {
         if (_unavailableEx==e && _unavailable!=0)
             return;
 
         _servletHandler.getServletContext().log("unavailable",e);
 
         _unavailableEx=e;
         _unavailable=-1;
         if (e.isPermanent())   
             _unavailable=-1;
         else
         {
             if (_unavailableEx.getUnavailableSeconds()>0)
                 _unavailable=System.currentTimeMillis()+1000*_unavailableEx.getUnavailableSeconds();
             else
                 _unavailable=System.currentTimeMillis()+5000; // TODO configure
         }
     }
     
 
     /* ------------------------------------------------------------ */
 
     private void makeUnavailable(Throwable e)
     {
         if (e instanceof UnavailableException)
             makeUnavailable((UnavailableException)e);
         else
         {
             _servletHandler.getServletContext().log("unavailable",e);
             _unavailableEx=new UnavailableException(e.toString(),-1);
             _unavailable=-1;
         }
     }
 
     /* ------------------------------------------------------------ */
     private void initServlet()
     	throws ServletException
     {
         Object old_run_as = null;
         try
         {
             if (_servlet==null)
                 _servlet=(Servlet)newInstance();
             if (_config==null)
                 _config=new Config();
 
             //handle any cusomizations of the servlet, such as @postConstruct
             if (!(_servlet instanceof SingleThreadedWrapper))
                 _servlet = getServletHandler().customizeServlet(_servlet);
             
             // Handle run as
             if (_identityService!=null)
             {
                 old_run_as=_identityService.setRunAs(_identityService.getSystemUserIdentity(),_runAsToken);
             }
 
             _servlet.init(_config);
         }
         catch (UnavailableException e)
         {
             makeUnavailable(e);
             _servlet=null;
             _config=null;
             throw e;
         }
         catch (ServletException e)
         {
             makeUnavailable(e.getCause()==null?e:e.getCause());
             _servlet=null;
             _config=null;
             throw e;
         }
         catch (Exception e)
         {
             makeUnavailable(e);
             _servlet=null;
             _config=null;
             throw new ServletException(this.toString(),e);
         }
         finally
         {
             // pop run-as role
             if (_identityService!=null)
                 _identityService.unsetRunAs(old_run_as);
         }
     }
     
     
     /* ------------------------------------------------------------ */
     /**
      * @see org.eclipse.jetty.server.UserIdentity.Scope#getContextPath()
      */
     public String getContextPath()
     {
         return _config.getServletContext().getContextPath();
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see org.eclipse.jetty.server.UserIdentity.Scope#getRoleRefMap()
      */
     public Map<String, String> getRoleRefMap()
     {
         return _roleMap;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see org.eclipse.jetty.server.UserIdentity.Scope#getRunAsRole()
      */
     public String getRunAsRole()
     {
         return _runAsRole;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Set the run-as role for this servlet
      * @param role run-as role for this servlet
      */
     public void setRunAsRole(String role)
     {
         _runAsRole=role;
     }
 
     /* ------------------------------------------------------------ */
     /** Service a request with this servlet.
      */
     public void handle(Request baseRequest,
                        ServletRequest request,
                        ServletResponse response)
         throws ServletException,
                UnavailableException,
                IOException
     {
         if (_class==null)
             throw new UnavailableException("Servlet Not Initialized");
         
         Servlet servlet=_servlet;
         synchronized(this)
         {
             if (_unavailable!=0 || !_initOnStartup)
                 servlet=getServlet();
             if (servlet==null)
                 throw new UnavailableException("Could not instantiate "+_class);
         }
         
         // Service the request
         boolean servlet_error=true;
         Object old_run_as = null;
         boolean suspendable = baseRequest.isAsyncSupported();
         try
         {
             // Handle aliased path
             if (_forcedPath!=null)
                 // TODO complain about poor naming to the Jasper folks
                 request.setAttribute("org.apache.catalina.jsp_file",_forcedPath);
 
             // Handle run as
             if (_identityService!=null)
                 old_run_as=_identityService.setRunAs(baseRequest.getResolvedUserIdentity(),_runAsToken);
             
             if (!isAsyncSupported())
                 baseRequest.setAsyncSupported(false);
             
             servlet.service(request,response);
             servlet_error=false;
         }
         catch(UnavailableException e)
         {
             makeUnavailable(e);
             throw _unavailableEx;
         }
         finally
         {
             baseRequest.setAsyncSupported(suspendable);
             
             // pop run-as role
             if (_identityService!=null)
                 _identityService.unsetRunAs(old_run_as);
 
             // Handle error params.
             if (servlet_error)
                 request.setAttribute("javax.servlet.error.servlet_name",getName());
         }
     }
 
  
     /* ------------------------------------------------------------ */
     /* ------------------------------------------------------------ */
     /* ------------------------------------------------------------ */
     protected class Config extends HolderConfig implements ServletConfig
     {   
         /* -------------------------------------------------------- */
         public String getServletName()
         {
             return getName();
         }
         
     }
 
     /* -------------------------------------------------------- */
     /* -------------------------------------------------------- */
     /* -------------------------------------------------------- */
     private class SingleThreadedWrapper implements Servlet
     {
         Stack _stack=new Stack();
         
         public void destroy()
         {
             synchronized(this)
             {
                 while(_stack.size()>0)
                     try { ((Servlet)_stack.pop()).destroy(); } catch (Exception e) { Log.warn(e); }
             }
         }
 
         public ServletConfig getServletConfig()
         {
             return _config;
         }
 
         public String getServletInfo()
         {
             return null;
         }
 
         public void init(ServletConfig config) throws ServletException
         {
             synchronized(this)
             {
                 if(_stack.size()==0)
                 {
                     try
                     {
                         Servlet s = (Servlet) newInstance();
                         s = getServletHandler().customizeServlet(s);
                         s.init(config);
                         _stack.push(s);
                     }
                     catch (ServletException e)
                     {
                         throw e;
                     }
                     catch (Exception e)
                     {
                         throw new ServletException(e);
                     }
                 }
             }
         }
 
         public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException
         {
             Servlet s;
             synchronized(this)
             {
                 if(_stack.size()>0)
                     s=(Servlet)_stack.pop();
                 else
                 {
                     try
                     {
                         s = (Servlet) newInstance();
                         s = getServletHandler().customizeServlet(s);
                         s.init(_config);
                     }
                     catch (ServletException e)
                     {
                         throw e;
                     }
                     catch (IOException e)
                     {
                         throw e;
                     }
                     catch (Exception e)
                     {
                         throw new ServletException(e);
                     }
                 }
             }
             
             try
             {
                 s.service(req,res);
             }
             finally
             {
                 synchronized(this)
                 {
                     _stack.push(s);
                 }
             }
         }
         
     }
 }