/*
    * 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.plugins;
  
  import org.apache.log4j.spi.ComponentBase;
  import org.apache.log4j.spi.LoggerRepository;
  
  import java.beans.PropertyChangeEvent;
  import java.beans.PropertyChangeListener;
  import java.beans.PropertyChangeSupport;
  
  
  /**
   * A convienent abstract class for plugin subclasses that implements
   * the basic methods of the Plugin interface. Subclasses are required
   * to implement the isActive(), activateOptions(), and shutdown()
   * methods.
   * <p></p>
   * <p>Developers are not required to subclass PluginSkeleton to
   * develop their own plugins (they are only required to implement the
   * Plugin interface), but it provides a convenient base class to start
   * from.
   * <p></p>
   * Contributors: Nicko Cadell
   *
   * @author Mark Womack (mwomack@apache.org)
   * @author Paul Smith (psmith@apache.org)
   */
  public abstract class PluginSkeleton extends ComponentBase implements Plugin {
      /**
       * Name of this plugin.
       */
      protected String name = "plugin";
  
      /**
       * Active state of plugin.
       */
      protected boolean active;
  
      /**
       * This is a delegate that does all the PropertyChangeListener
       * support.
       */
      private PropertyChangeSupport propertySupport =
          new PropertyChangeSupport(this);
  
      /**
       * Construct new instance.
       */
      protected PluginSkeleton() {
          super();
      }
  
      /**
       * Gets the name of the plugin.
       *
       * @return String the name of the plugin.
       */
      public String getName() {
          return name;
      }
  
      /**
       * Sets the name of the plugin and notifies
       * PropertyChangeListeners of the change.
       *
       * @param newName the name of the plugin to set.
       */
      public void setName(final String newName) {
          String oldName = this.name;
          this.name = newName;
          propertySupport.firePropertyChange("name", oldName, this.name);
      }
  
      /**
       * Gets the logger repository for this plugin.
       *
       * @return LoggerRepository the logger repository this plugin will affect.
       */
      public LoggerRepository getLoggerRepository() {
          return repository;
      }
  
      /**
      * Sets the logger repository used by this plugin and notifies a
      * relevant PropertyChangeListeners registered. This
      * repository will be used by the plugin functionality.
      *
      * @param repository the logger repository that this plugin should affect.
      */
     public void setLoggerRepository(final LoggerRepository repository) {
         Object oldValue = this.repository;
         this.repository = repository;
         firePropertyChange("loggerRepository", oldValue, this.repository);
     }
 
     /**
      * Returns whether this plugin is Active or not.
      *
      * @return true/false
      */
     public synchronized boolean isActive() {
         return active;
     }
 
     /**
      * Returns true if the plugin has the same name and logger repository as the
      * testPlugin passed in.
      *
      * @param testPlugin The plugin to test equivalency against.
      * @return Returns true if testPlugin is considered to be equivalent.
      */
     public boolean isEquivalent(final Plugin testPlugin) {
         return (repository == testPlugin.getLoggerRepository())
             && ((this.name == null && testPlugin.getName() == null)
             || (this.name != null
             && name.equals(testPlugin.getName())))
             && this.getClass().equals(testPlugin.getClass());
     }
 
     /**
      * Add property change listener.
      *
      * @param listener listener.
      */
     public final void addPropertyChangeListener(
         final PropertyChangeListener listener) {
         propertySupport.addPropertyChangeListener(listener);
     }
 
     /**
      * Add property change listener for one property only.
      *
      * @param propertyName property name.
      * @param listener     listener.
      */
     public final void addPropertyChangeListener(
         final String propertyName,
         final PropertyChangeListener listener) {
         propertySupport.addPropertyChangeListener(propertyName, listener);
     }
 
     /**
      * Remove property change listener.
      *
      * @param listener listener.
      */
     public final void removePropertyChangeListener(
         final PropertyChangeListener listener) {
         propertySupport.removePropertyChangeListener(listener);
     }
 
     /**
      * Remove property change listener on a specific property.
      *
      * @param propertyName property name.
      * @param listener     listener.
      */
     public final void removePropertyChangeListener(
         final String propertyName,
         final PropertyChangeListener listener) {
         propertySupport.removePropertyChangeListener(propertyName, listener);
     }
 
     /**
      * Fire a property change event to appropriate listeners.
      *
      * @param evt change event.
      */
     protected final void firePropertyChange(
         final PropertyChangeEvent evt) {
         propertySupport.firePropertyChange(evt);
     }
 
     /**
      * Fire property change event to appropriate listeners.
      *
      * @param propertyName property name.
      * @param oldValue     old value.
      * @param newValue     new value.
      */
     protected final void firePropertyChange(
         final String propertyName,
         final boolean oldValue,
         final boolean newValue) {
         propertySupport.firePropertyChange(propertyName, oldValue, newValue);
     }
 
     /**
      * Fire property change event to appropriate listeners.
      *
      * @param propertyName property name.
      * @param oldValue     old value.
      * @param newValue     new value.
      */
     protected final void firePropertyChange(
         final String propertyName,
         final int oldValue, final int newValue) {
         propertySupport.firePropertyChange(propertyName, oldValue, newValue);
     }
 
     /**
      * Fire property change event to appropriate listeners.
      *
      * @param propertyName property name.
      * @param oldValue     old value.
      * @param newValue     new value.
      */
     protected final void firePropertyChange(
         final String propertyName,
         final Object oldValue,
         final Object newValue) {
         propertySupport.firePropertyChange(propertyName, oldValue, newValue);
     }
 }