//
   //  ========================================================================
   //  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.monitor.triggers;
  
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  
  import javax.management.MBeanServerConnection;
  import javax.management.MalformedObjectNameException;
  import javax.management.ObjectName;
  import javax.management.openmbean.CompositeData;
  
  import org.eclipse.jetty.monitor.JMXMonitor;
  import org.eclipse.jetty.monitor.jmx.EventState;
  import org.eclipse.jetty.monitor.jmx.EventTrigger;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  
  
  /* ------------------------------------------------------------ */
  /**
   * AttrEventTrigger
   * 
   * Event trigger that polls a value of an MXBean attribute
   * and matches every invocation of this trigger. It can be
   * used to send notifications of the value of an attribute
   * of the MXBean being polled at a certain interval, or as
   * a base class for the event triggers that match the 
   * value of an attribute of the MXBean being polled against
   * some specified criteria.
   */
  public class AttrEventTrigger<TYPE extends Comparable<TYPE>> 
      extends EventTrigger
  {
      private static final Logger LOG = Log.getLogger(AttrEventTrigger.class);
     
      private final ObjectName _nameObject;
  
      protected final String _objectName;
      protected final String _attributeName;
      protected Map<Long, EventState<TYPE>> _states;
      
      /* ------------------------------------------------------------ */
      /**
       * Construct event trigger and specify the MXBean attribute
       * that will be polled by this event trigger.
       * 
       * @param objectName object name of an MBean to be polled
       * @param attributeName name of an MBean attribute to be polled
       * 
       * @throws MalformedObjectNameException
       * @throws IllegalArgumentException
       */
      public AttrEventTrigger(String objectName, String attributeName)
          throws MalformedObjectNameException, IllegalArgumentException
      {
          if (objectName == null)
              throw new IllegalArgumentException("Object name cannot be null");
          if (attributeName == null)
              throw new IllegalArgumentException("Attribute name cannot be null");
          
          _states =  new ConcurrentHashMap<Long,EventState<TYPE>>();
          
          _objectName = objectName;
          _attributeName = attributeName;
          
          _nameObject = new ObjectName(_objectName);
      }
  
      /* ------------------------------------------------------------ */
      /**
       * Construct event trigger and specify the MXBean attribute
       * that will be polled by this event trigger.
       * 
       * @param nameObject object name of an MBean to be polled
       * @param attributeName name of an MBean attribute to be polled
       * 
       * @throws IllegalArgumentException
       */
      public AttrEventTrigger(ObjectName nameObject, String attributeName)
          throws IllegalArgumentException
      {
         if (nameObject == null)
             throw new IllegalArgumentException("Object name cannot be null");
         if (attributeName == null)
             throw new IllegalArgumentException("Attribute name cannot be null");
         
         _states =  new ConcurrentHashMap<Long,EventState<TYPE>>();
         
         _objectName = nameObject.toString();
         _attributeName = attributeName;
         
         _nameObject = nameObject;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Verify if the event trigger conditions are in the 
      * appropriate state for an event to be triggered.
      * This event trigger uses the match(Comparable<TYPE>)
      * method to compare the value of the MXBean attribute
      * to the conditions specified by the subclasses.
      * 
      * @see org.eclipse.jetty.monitor.jmx.EventTrigger#match(long)
      */
     @SuppressWarnings("unchecked")
     public final boolean match(long timestamp) 
         throws Exception
     {
         MBeanServerConnection serverConnection = JMXMonitor.getServiceConnection();
 
         TYPE value = null;
         try
         {
             int pos = _attributeName.indexOf('.');
             if (pos < 0)
                 value = (TYPE)serverConnection.getAttribute(_nameObject,_attributeName);
             else
                 value =  getValue((CompositeData)serverConnection.getAttribute(_nameObject, _attributeName.substring(0, pos)),
                                   _attributeName.substring(pos+1));
         }
         catch (Exception ex)
         {
             LOG.debug(ex);
         }
 
         boolean result = false;
         if (value != null)
         {
             result = match(value);
             
             if (result || getSaveAll())
             {
                 _states.put(timestamp, 
                             new EventState<TYPE>(this.getID(), this.getNameString(), value));
             }
         }
             
         return result;
     }
     
     
     /* ------------------------------------------------------------ */
     /**
      * Verify if the event trigger conditions are in the 
      * appropriate state for an event to be triggered.
      * Allows subclasses to override the default behavior
      * that matches every invocation of this trigger
      */
     public boolean match(Comparable<TYPE> value)
     {
         return true;
     }
     
     /* ------------------------------------------------------------ */
     /**
      * Retrieve the event state associated with specified invocation
      * of the event trigger match method. 
      * 
      * @param timestamp time stamp associated with invocation
      * @return event state or null if not found
      *
      * @see org.eclipse.jetty.monitor.jmx.EventTrigger#getState(long)
      */
     @Override
     public final EventState<TYPE> getState(long timestamp)
     {
         return _states.get(timestamp);
     }
     
     /* ------------------------------------------------------------ */
     /**
      * Returns the string representation of this event trigger
      * in the format "[object_name:attribute_name]". 
      * 
      * @return string representation of the event trigger
      * 
      * @see java.lang.Object#toString()
      */
     public String toString()
     {
         return getNameString();
     }
     
     /* ------------------------------------------------------------ */
     /**
      * Returns the string representation of this event trigger
      * in the format "[object_name:attribute_name]". Allows
      * subclasses to override the name string used to identify
      * this event trigger in the event state object as well as
      * string representation of the subclasses.
      * 
      * @return string representation of the event trigger
      */
     protected String getNameString()
     {
         StringBuilder result = new StringBuilder();
         
         result.append('[');
         result.append(_objectName);
         result.append(":");
         result.append(_attributeName);
         result.append("]");
         
         return result.toString();
     }
 
     protected boolean getSaveAll()
     {
         return true;
     }
     
     protected TYPE getValue(CompositeData compValue, String fieldName)
     {
         int pos = fieldName.indexOf('.');
         if (pos < 0)
             return (TYPE)compValue.get(fieldName);
         else
             return getValue((CompositeData)compValue.get(fieldName.substring(0, pos)), 
                             fieldName.substring(pos+1));
           
     }
 }