/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    * 
    *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.log4j.jmx;
  
  import java.util.Enumeration;
  import java.util.Iterator;
  import java.util.Vector;
  
  import javax.management.Attribute;
  import javax.management.AttributeList;
  import javax.management.DynamicMBean;
  import javax.management.InstanceAlreadyExistsException;
  import javax.management.InstanceNotFoundException;
  import javax.management.JMException;
  import javax.management.MBeanRegistration;
  import javax.management.MBeanRegistrationException;
  import javax.management.MBeanServer;
  import javax.management.NotCompliantMBeanException;
  import javax.management.ObjectName;
  import javax.management.RuntimeOperationsException;
  
  import org.apache.log4j.Logger;
  import org.apache.log4j.Appender;
  
  public abstract class AbstractDynamicMBean implements DynamicMBean,
                                                        MBeanRegistration {
  
    String dClassName;
    MBeanServer server;
    private final Vector mbeanList = new Vector();
  
      /**
       * Get MBean name.
       * @param appender appender, may not be null.
       * @return name.
       * @since 1.2.16
       */
    static protected String getAppenderName(final Appender appender){
        String name = appender.getName();
        if (name == null || name.trim().length() == 0) {
            // try to get some form of a name, because null is not allowed (exception), and empty string certainly isn't useful in JMX..
            name = appender.toString();
        }
        return name;
    }
        
  
    /**
     * Enables the to get the values of several attributes of the Dynamic MBean.
     */
    public
    AttributeList getAttributes(String[] attributeNames) {
  
      // Check attributeNames is not null to avoid NullPointerException later on
      if (attributeNames == null) {
        throw new RuntimeOperationsException(
  			   new IllegalArgumentException("attributeNames[] cannot be null"),
  			   "Cannot invoke a getter of " + dClassName);
      }
  
      AttributeList resultList = new AttributeList();
  
      // if attributeNames is empty, return an empty result list
      if (attributeNames.length == 0)
        return resultList;
  
      // build the result attribute list
      for (int i=0 ; i<attributeNames.length ; i++){
        try {
  	Object value = getAttribute((String) attributeNames[i]);
  	resultList.add(new Attribute(attributeNames[i],value));
        } catch (JMException e) {
  	     e.printStackTrace();
        } catch (RuntimeException e) {
  	     e.printStackTrace();
        }
      }
      return(resultList);
    }
  
    /**
     * Sets the values of several attributes of the Dynamic MBean, and returns the
     * list of attributes that have been set.
     */
   public AttributeList setAttributes(AttributeList attributes) {
 
     // Check attributes is not null to avoid NullPointerException later on
     if (attributes == null) {
       throw new RuntimeOperationsException(
                     new IllegalArgumentException("AttributeList attributes cannot be null"),
 		    "Cannot invoke a setter of " + dClassName);
     }
     AttributeList resultList = new AttributeList();
 
     // if attributeNames is empty, nothing more to do
     if (attributes.isEmpty())
       return resultList;
 
     // for each attribute, try to set it and add to the result list if successfull
     for (Iterator i = attributes.iterator(); i.hasNext();) {
       Attribute attr = (Attribute) i.next();
       try {
 	setAttribute(attr);
 	String name = attr.getName();
 	Object value = getAttribute(name);
 	resultList.add(new Attribute(name,value));
       } catch(JMException e) {
 	    e.printStackTrace();
       } catch(RuntimeException e) {
 	    e.printStackTrace();
       }
     }
     return(resultList);
   }
 
   protected
   abstract
   Logger getLogger();
 
   public
   void postDeregister() {
     getLogger().debug("postDeregister is called.");
   }
 
   public
   void postRegister(java.lang.Boolean registrationDone) {
   }
 
 
 
   public
   ObjectName preRegister(MBeanServer server, ObjectName name) {
     getLogger().debug("preRegister called. Server="+server+ ", name="+name);
     this.server = server;
     return name;
   }
   /**
    * Registers MBean instance in the attached server. Must <em>NOT</em>
    * be called before registration of this instance.
    */
   protected
   void registerMBean(Object mbean, ObjectName objectName)
   throws InstanceAlreadyExistsException, MBeanRegistrationException,
                    NotCompliantMBeanException {
     server.registerMBean(mbean, objectName);
     mbeanList.add(objectName);
   }
 
   /**
    * Performs cleanup for deregistering this MBean. Default implementation
    * unregisters MBean instances which are registered using 
    * {@link #registerMBean(Object mbean, ObjectName objectName)}.
    */
    public
    void preDeregister() {
      getLogger().debug("preDeregister called.");
      
     Enumeration iterator = mbeanList.elements();
     while (iterator.hasMoreElements()) {
       ObjectName name = (ObjectName) iterator.nextElement();
       try {
         server.unregisterMBean(name);
       } catch (InstanceNotFoundException e) {
    getLogger().warn("Missing MBean " + name.getCanonicalName());
       } catch (MBeanRegistrationException e) {
    getLogger().warn("Failed unregistering " + name.getCanonicalName());
       }
     }
    }
 
 
 }