//
   //  ========================================================================
   //  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.server.handler;
  
  import java.io.IOException;
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.concurrent.atomic.AtomicLong;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jetty.continuation.Continuation;
  import org.eclipse.jetty.continuation.ContinuationListener;
  import org.eclipse.jetty.server.AsyncContinuation;
  import org.eclipse.jetty.server.Request;
  import org.eclipse.jetty.server.Response;
  import org.eclipse.jetty.util.statistic.CounterStatistic;
  import org.eclipse.jetty.util.statistic.SampleStatistic;
  
  public class StatisticsHandler extends HandlerWrapper
  {
      private final AtomicLong _statsStartedAt = new AtomicLong();
      
      private final CounterStatistic _requestStats = new CounterStatistic();
      private final SampleStatistic _requestTimeStats = new SampleStatistic();
      private final CounterStatistic _dispatchedStats = new CounterStatistic();
      private final SampleStatistic _dispatchedTimeStats = new SampleStatistic();
      private final CounterStatistic _suspendStats = new CounterStatistic();
  
      private final AtomicInteger _resumes = new AtomicInteger();
      private final AtomicInteger _expires = new AtomicInteger();
      
      private final AtomicInteger _responses1xx = new AtomicInteger();
      private final AtomicInteger _responses2xx = new AtomicInteger();
      private final AtomicInteger _responses3xx = new AtomicInteger();
      private final AtomicInteger _responses4xx = new AtomicInteger();
      private final AtomicInteger _responses5xx = new AtomicInteger();
      private final AtomicLong _responsesTotalBytes = new AtomicLong();
  
      private final ContinuationListener _onCompletion = new ContinuationListener()
      {
          public void onComplete(Continuation continuation)
          {
              final Request request = ((AsyncContinuation)continuation).getBaseRequest();
              final long elapsed = System.currentTimeMillis()-request.getTimeStamp();
              
              _requestStats.decrement();
              _requestTimeStats.set(elapsed);
              
              updateResponse(request);
              
              if (!continuation.isResumed())
                  _suspendStats.decrement();
          }
  
          public void onTimeout(Continuation continuation)
          {
              _expires.incrementAndGet();
          }
      };
      
      /**
       * Resets the current request statistics.
       */
      public void statsReset()
      {
          _statsStartedAt.set(System.currentTimeMillis());
          
          _requestStats.reset();
          _requestTimeStats.reset();
          _dispatchedStats.reset();
          _dispatchedTimeStats.reset();
          _suspendStats.reset();
  
          _resumes.set(0);
          _expires.set(0);
          _responses1xx.set(0);
          _responses2xx.set(0);
          _responses3xx.set(0);
          _responses4xx.set(0);
          _responses5xx.set(0);
          _responsesTotalBytes.set(0L);
     }
 
     @Override
     public void handle(String path, Request request, HttpServletRequest httpRequest, HttpServletResponse httpResponse) throws IOException, ServletException
     {
         _dispatchedStats.increment();
 
         final long start;
         AsyncContinuation continuation = request.getAsyncContinuation();
         if (continuation.isInitial())
         {
             // new request
             _requestStats.increment();
             start = request.getTimeStamp();
         }
         else
         {
             // resumed request
             start = System.currentTimeMillis();
             _suspendStats.decrement();
             if (continuation.isResumed())
                 _resumes.incrementAndGet();
         }
 
         try
         {
             super.handle(path, request, httpRequest, httpResponse);
         }
         finally
         {
             final long now = System.currentTimeMillis();
             final long dispatched=now-start;
             
             _dispatchedStats.decrement();
             _dispatchedTimeStats.set(dispatched);
             
             if (continuation.isSuspended())
             {
                 if (continuation.isInitial())
                     continuation.addContinuationListener(_onCompletion);
                 _suspendStats.increment();
             }
             else if (continuation.isInitial())
             {
                 _requestStats.decrement();
                 _requestTimeStats.set(dispatched);
                 updateResponse(request);
             }
             // else onCompletion will handle it.
         }
     }
 
     private void updateResponse(Request request)
     {
         Response response = request.getResponse();
         switch (response.getStatus() / 100)
         {
             case 1:
                 _responses1xx.incrementAndGet();
                 break;
             case 2:
                 _responses2xx.incrementAndGet();
                 break;
             case 3:
                 _responses3xx.incrementAndGet();
                 break;
             case 4:
                 _responses4xx.incrementAndGet();
                 break;
             case 5:
                 _responses5xx.incrementAndGet();
                 break;
             default:
                 break;
         }
         _responsesTotalBytes.addAndGet(response.getContentCount());
     }
 
     @Override
     protected void doStart() throws Exception
     {
         super.doStart();
         statsReset();
     }
 
     /**
      * @return the number of requests handled by this handler
      * since {@link #statsReset()} was last called, excluding
      * active requests
      * @see #getResumes()
      */
     public int getRequests()
     {
         return (int)_requestStats.getTotal();
     }
 
     /**
      * @return the number of requests currently active.
      * since {@link #statsReset()} was last called.
      */
     public int getRequestsActive()
     {
         return (int)_requestStats.getCurrent();
     }
 
     /**
      * @return the maximum number of active requests
      * since {@link #statsReset()} was last called.
      */
     public int getRequestsActiveMax()
     {
         return (int)_requestStats.getMax();
     }
 
     /**
      * @return the maximum time (in milliseconds) of request handling
      * since {@link #statsReset()} was last called.
      */
     public long getRequestTimeMax()
     {
         return _requestTimeStats.getMax();
     }
 
     /**
      * @return the total time (in milliseconds) of requests handling
      * since {@link #statsReset()} was last called.
      */
     public long getRequestTimeTotal()
     {
         return _requestTimeStats.getTotal();
     }
 
     /**
      * @return the mean time (in milliseconds) of request handling
      * since {@link #statsReset()} was last called.
      * @see #getRequestTimeTotal()
      * @see #getRequests()
      */
     public double getRequestTimeMean()
     {
         return _requestTimeStats.getMean();
     }
 
     /**
      * @return the standard deviation of time (in milliseconds) of request handling
      * since {@link #statsReset()} was last called.
      * @see #getRequestTimeTotal()
      * @see #getRequests()
      */
     public double getRequestTimeStdDev()
     {
         return _requestTimeStats.getStdDev();
     }
 
     /**
      * @return the number of dispatches seen by this handler
      * since {@link #statsReset()} was last called, excluding
      * active dispatches
      */
     public int getDispatched()
     {
         return (int)_dispatchedStats.getTotal();
     }
 
     /**
      * @return the number of dispatches currently in this handler
      * since {@link #statsReset()} was last called, including
      * resumed requests
      */
     public int getDispatchedActive()
     {
         return (int)_dispatchedStats.getCurrent();
     }
 
     /**
      * @return the max number of dispatches currently in this handler
      * since {@link #statsReset()} was last called, including
      * resumed requests
      */
     public int getDispatchedActiveMax()
     {
         return (int)_dispatchedStats.getMax();
     }
 
     /**
      * @return the maximum time (in milliseconds) of request dispatch
      * since {@link #statsReset()} was last called.
      */
     public long getDispatchedTimeMax()
     {
         return _dispatchedTimeStats.getMax();
     }
     
     /**
      * @return the total time (in milliseconds) of requests handling
      * since {@link #statsReset()} was last called.
      */
     public long getDispatchedTimeTotal()
     {
         return _dispatchedTimeStats.getTotal();
     }
 
     /**
      * @return the mean time (in milliseconds) of request handling
      * since {@link #statsReset()} was last called.
      * @see #getRequestTimeTotal()
      * @see #getRequests()
      */
     public double getDispatchedTimeMean()
     {
         return _dispatchedTimeStats.getMean();
     }
     
     /**
      * @return the standard deviation of time (in milliseconds) of request handling
      * since {@link #statsReset()} was last called.
      * @see #getRequestTimeTotal()
      * @see #getRequests()
      */
     public double getDispatchedTimeStdDev()
     {
         return _dispatchedTimeStats.getStdDev();
     }
     
     /**
      * @return the number of requests handled by this handler
      * since {@link #statsReset()} was last called, including
      * resumed requests
      * @see #getResumes()
      */
     public int getSuspends()
     {
         return (int)_suspendStats.getTotal();
     }
 
     /**
      * @return the number of requests currently suspended.
      * since {@link #statsReset()} was last called.
      */
     public int getSuspendsActive()
     {
         return (int)_suspendStats.getCurrent();
     }
 
     /**
      * @return the maximum number of current suspended requests
      * since {@link #statsReset()} was last called.
      */
     public int getSuspendsActiveMax()
     {
         return (int)_suspendStats.getMax();
     }
     
     /**
      * @return the number of requests that have been resumed
      * @see #getExpires()
      */
     public int getResumes()
     {
         return _resumes.get();
     }
 
     /**
      * @return the number of requests that expired while suspended.
      * @see #getResumes()
      */
     public int getExpires()
     {
         return _expires.get();
     }
 
     /**
      * @return the number of responses with a 1xx status returned by this context
      * since {@link #statsReset()} was last called.
      */
     public int getResponses1xx()
     {
         return _responses1xx.get();
     }
 
     /**
      * @return the number of responses with a 2xx status returned by this context
      * since {@link #statsReset()} was last called.
      */
     public int getResponses2xx()
     {
         return _responses2xx.get();
     }
 
     /**
      * @return the number of responses with a 3xx status returned by this context
      * since {@link #statsReset()} was last called.
      */
     public int getResponses3xx()
     {
         return _responses3xx.get();
     }
 
     /**
      * @return the number of responses with a 4xx status returned by this context
      * since {@link #statsReset()} was last called.
      */
     public int getResponses4xx()
     {
         return _responses4xx.get();
     }
 
     /**
      * @return the number of responses with a 5xx status returned by this context
      * since {@link #statsReset()} was last called.
      */
     public int getResponses5xx()
     {
         return _responses5xx.get();
     }
 
     /**
      * @return the milliseconds since the statistics were started with {@link #statsReset()}.
      */
     public long getStatsOnMs()
     {
         return System.currentTimeMillis() - _statsStartedAt.get();
     }
     
     /**
      * @return the total bytes of content sent in responses
      */
     public long getResponsesBytesTotal()
     {
         return _responsesTotalBytes.get();
     }
     
     public String toStatsHTML()
     {   
         StringBuilder sb = new StringBuilder();
 
         sb.append("<h1>Statistics:</h1>\n");
         sb.append("Statistics gathering started ").append(getStatsOnMs()).append("ms ago").append("<br />\n");
 
         sb.append("<h2>Requests:</h2>\n");
         sb.append("Total requests: ").append(getRequests()).append("<br />\n");
         sb.append("Active requests: ").append(getRequestsActive()).append("<br />\n");
         sb.append("Max active requests: ").append(getRequestsActiveMax()).append("<br />\n");
         sb.append("Total requests time: ").append(getRequestTimeTotal()).append("<br />\n");
         sb.append("Mean request time: ").append(getRequestTimeMean()).append("<br />\n");
         sb.append("Max request time: ").append(getRequestTimeMax()).append("<br />\n");
         sb.append("Request time standard deviation: ").append(getRequestTimeStdDev()).append("<br />\n");
         
 
         sb.append("<h2>Dispatches:</h2>\n");
         sb.append("Total dispatched: ").append(getDispatched()).append("<br />\n");
         sb.append("Active dispatched: ").append(getDispatchedActive()).append("<br />\n");
         sb.append("Max active dispatched: ").append(getDispatchedActiveMax()).append("<br />\n");
         sb.append("Total dispatched time: ").append(getDispatchedTimeTotal()).append("<br />\n");
         sb.append("Mean dispatched time: ").append(getDispatchedTimeMean()).append("<br />\n");
         sb.append("Max dispatched time: ").append(getDispatchedTimeMax()).append("<br />\n");
         sb.append("Dispatched time standard deviation: ").append(getDispatchedTimeStdDev()).append("<br />\n");
 
 
         sb.append("Total requests suspended: ").append(getSuspends()).append("<br />\n");
         sb.append("Total requests expired: ").append(getExpires()).append("<br />\n");
         sb.append("Total requests resumed: ").append(getResumes()).append("<br />\n");
         
         sb.append("<h2>Responses:</h2>\n");
         sb.append("1xx responses: ").append(getResponses1xx()).append("<br />\n");
         sb.append("2xx responses: ").append(getResponses2xx()).append("<br />\n");
         sb.append("3xx responses: ").append(getResponses3xx()).append("<br />\n");
         sb.append("4xx responses: ").append(getResponses4xx()).append("<br />\n");
         sb.append("5xx responses: ").append(getResponses5xx()).append("<br />\n");
         sb.append("Bytes sent total: ").append(getResponsesBytesTotal()).append("<br />\n");
 
         return sb.toString();
 
     }
 }