package nl.tudelft.simulation.naming.context.event;
   
   import java.util.LinkedHashMap;
   import java.util.Map;
   import java.util.Map.Entry;
   import java.util.regex.Pattern;
   
   import javax.naming.InvalidNameException;
   import javax.naming.NameNotFoundException;
  import javax.naming.NamingException;
  import javax.naming.NotContextException;
  
  import org.djutils.event.Event;
  import org.djutils.event.EventListener;
  import org.djutils.event.LocalEventProducer;
  import org.djutils.event.reference.ReferenceType;
  import org.djutils.exceptions.Throw;
  
  import nl.tudelft.simulation.naming.context.ContextInterface;
  
  /**
   * ContextEventProducerImpl carries out the implementation for the EventContext classes. The class registers as a listener on
   * the root of the InitialEventContext or the RemoteEventContext. Whenever sub-contexts are added (these will typically not be
   * of type EventContext, but rather of type JvmContext, FileContext, RemoteContext, or other), this class also registers as a
   * listener on these sub-contexts. Thereby, it remains aware of all changes happening in the sub-contexts of which it may be
   * notified.<br>
   * <br>
   * For listening, four different ContextScope options exist:
   * <ul>
   * <li><b>OBJECT_SCOPE</b>: listen to the changes in the object. OBJECT_SCOPE can be applied to regular objects and to context
   * objects. When the object is at a leaf position in the tree, OBJECT_CHANGED events will be fired to the listener(s) on a
   * change of the leaf object, and OBJECT_REMOVED events when the leaf is removed from the context. When the object is a context,
   * OBJECT_REMOVED is fired when the sub-context is removed from its parent context.</li>
   * <li><b>LEVEL_SCOPE</b>: fires events when changes happen in the provided context. LEVEL_SCOPE can only be applied to context
   * objects. OBJECT_ADDED is fired when an object (context or leaf) is added to the context; OBJECT_REMOVED when an object
   * (context or leaf) is removed from the context; OBJECT_CHANGED when one of the leaf objects present in the provided context
   * had changes in its content. OBJECT_REMOVED is <b>not</b> fired when the sub-context is removed from the parent context.</li>
   * <li><b>LEVEL_OBJECT_SCOPE</b>: fires events when changes happen in the provided context. LEVEL_OBJECT_SCOPE can only be
   * applied to context objects. OBJECT_ADDED is fired when an object (context or leaf) is added to the context; OBJECT_REMOVED
   * when an object (context or leaf) is removed from the context; OBJECT_CHANGED when one of the leaf objects present in the
   * provided context had changes in its content. OBJECT_REMOVED <b>is also</b> fired when the sub-context is removed from the
   * parent context.</li>
   * <li><b>SUBTREE_SCOPE</b>: fires events when changes happen in the provided context, and any context deeper in the tree
   * descending from the provided context. SUBTREE_SCOPE can only be applied to context objects. OBJECT_ADDED is fired when an
   * object (context or leaf) is added to the context, or any of its descendant contexts; OBJECT_REMOVED when an object (context
   * or leaf) is removed from the context or a descendant context; OBJECT_CHANGED when one of the leaf objects present in the
   * provided context or any descendant context had changes in its content. OBJECT_REMOVED <b>is also</b> fired when the
   * sub-context is removed from the parent context.</li>
   * </ul>
   * The listeners to be notified are determined with a regular expression. Examples of this regular expression are given below.
   * <ul>
   * <li><b>OBJECT_SCOPE</b>: Suppose we are interested in changes to the object registered under "/simulation1/sub1/myobject". In
   * that case, the regular expression is "/simulation1/sub1/myobject" as we are only interested in changes to the object
   * registered under this key.</li>
   * <li><b>LEVEL_SCOPE</b>: Suppose we are interested in changes to the objects registered <i>directly</i> under
   * "/simulation1/sub1", excluding the sub1 context itself. In that case, the regular expression is "/simulation1/sub1/[^/]+$" as
   * we are only interested in changes to the objects registered under this key, so minimally one character after the key that
   * cannot be a forward slash, as that would indicate a subcontext.</li>
   * <li><b>LEVEL_OBJECT_SCOPE</b>: Suppose we are interested in changes to the objects registered <i>directly</i> under
   * "/simulation1/sub1", including the "/simulation1/sub1" context itself. In that case, the regular expression is
   * "/simulation1/sub1(/[^/]*$)?" as we are interested in changes to the objects directly registered under this key, so minimally
   * one character after the key that cannot be a forward slash. The context "sub1" itself is also included, with or without a
   * forward slash at the end.</li>
   * <li><b>SUBTREE_SCOPE</b>: Suppose we are interested in changes to the objects registered in the total subtree under
   * "/simulation1/sub1", including the "/simulation1/sub1" context itself. In that case, the regular expression is
   * "/simulation1/sub1(/.*)?". The context "sub1" itself is also included, with or without a forward slash at the end.</li>
   * </ul>
   * <p>
   * Copyright (c) 2020-2025 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
   * for project information <a href="https://simulation.tudelft.nl/dsol/manual/" target="_blank">DSOL Manual</a>. The DSOL
   * project is distributed under a three-clause BSD-style license, which can be found at
   * <a href="https://simulation.tudelft.nl/dsol/docs/latest/license.html" target="_blank">DSOL License</a>.
   * </p>
   * @author <a href="https://github.com/averbraeck" target="_blank">Alexander Verbraeck</a>
   */
  public class ContextEventProducerImpl extends LocalEventProducer implements EventListener
  {
      /**
       * The registry for the listeners. The key of the map is made from the given path to listen followed by a hash sign and the
       * toString of the used ContextScope enum. String has a cached hash.
       */
      private Map<String, PatternListener> regExpListenerMap = new LinkedHashMap<>();
  
      /**
       * The records for the scope listeners so we can find them back for removal. The key of the map is made from the given path
       * to listen followed by a hash sign and the toString of the used ContextScope enum. String has a cached hash.
       */
      private Map<String, PatternListener> registryMap = new LinkedHashMap<>();
  
      /** the EventContext for which we do the work. */
      private final EventContext parent;
  
      /**
       * Create the ContextEventProducerImpl and link to the parent class.
       * @param parent the EventContext for which we do the work
       */
      public ContextEventProducerImpl(final EventContext parent)
      {
          super();
         this.parent = parent;
 
         // we subscribe ourselves to the OBJECT_ADDED, OBJECT_REMOVED and OBJECT_CHANGED events of the parent
         this.parent.addListener(this, ContextInterface.OBJECT_ADDED_EVENT, ReferenceType.WEAK);
         this.parent.addListener(this, ContextInterface.OBJECT_REMOVED_EVENT, ReferenceType.WEAK);
         this.parent.addListener(this, ContextInterface.OBJECT_CHANGED_EVENT, ReferenceType.WEAK);
     }
 
     @Override
     public void notify(final Event event)
     {
         Object[] content = (Object[]) event.getContent();
         if (event.getType().equals(ContextInterface.OBJECT_ADDED_EVENT))
         {
             if (content[2] instanceof ContextInterface)
             {
                 ContextInterface context = (ContextInterface) content[2];
                 context.addListener(this, ContextInterface.OBJECT_ADDED_EVENT);
                 context.addListener(this, ContextInterface.OBJECT_REMOVED_EVENT);
                 context.addListener(this, ContextInterface.OBJECT_CHANGED_EVENT);
             }
             for (Entry<String, PatternListener> entry : this.regExpListenerMap.entrySet())
             {
                 String path = (String) content[0] + ContextInterface.SEPARATOR + (String) content[1];
                 if (entry.getValue().getPattern().matcher(path).matches())
                 {
                     entry.getValue().getListener().notify(event);
                 }
             }
         }
         else if (event.getType().equals(ContextInterface.OBJECT_REMOVED_EVENT))
         {
             if (content[2] instanceof ContextInterface)
             {
                 ContextInterface context = (ContextInterface) content[2];
                 context.removeListener(this, ContextInterface.OBJECT_ADDED_EVENT);
                 context.removeListener(this, ContextInterface.OBJECT_REMOVED_EVENT);
                 context.removeListener(this, ContextInterface.OBJECT_CHANGED_EVENT);
             }
             for (Entry<String, PatternListener> entry : this.regExpListenerMap.entrySet())
             {
                 String path = (String) content[0] + ContextInterface.SEPARATOR + (String) content[1];
                 if (entry.getValue().getPattern().matcher(path).matches())
                 {
                     entry.getValue().getListener().notify(event);
                 }
             }
         }
         else if (event.getType().equals(ContextInterface.OBJECT_CHANGED_EVENT))
         {
             for (Entry<String, PatternListener> entry : this.regExpListenerMap.entrySet())
             {
                 String path = (String) content[0] + ContextInterface.SEPARATOR + (String) content[1];
                 if (entry.getValue().getPattern().matcher(path).matches())
                 {
                     entry.getValue().getListener().notify(event);
                 }
             }
         }
     }
 
     /**
      * Make a key consisting of the full path of the subcontext (without the trailing slash) or object in the context tree,
      * followed by a hash code (#) and the context scope string (OBJECT_SCOPE, LEVEL_SCOPE, LEVEL_OBJECT_SCOPE, or
      * SUBTREE_SCOPE).
      * @param absolutePath the path for which the key has to be made. The path can point to an object or a subcontext
      * @param contextScope the scope for which the key has to be made
      * @return a concatenation of the path, a hash (#) and the context scope
      */
     protected String makeRegistryKey(final String absolutePath, final ContextScope contextScope)
     {
         String key = absolutePath;
         if (key.endsWith("/"))
         {
             key = key.substring(0, key.length() - 1);
         }
         key += "#" + contextScope.name();
         return key;
     }
 
     /**
      * Make a regular expression that matches the right paths to be matched. The regular expression per scope is:
      * <ul>
      * <li><b>OBJECT_SCOPE</b>: Suppose we are interested in changes to the object registered under
      * "/simulation1/sub1/myobject". In that case, the regular expression is "/simulation1/sub1/myobject" as we are only
      * interested in changes to the object registered under this key.</li>
      * <li><b>LEVEL_SCOPE</b>: Suppose we are interested in changes to the objects registered <i>directly</i> under
      * "/simulation1/sub1", excluding the sub1 context itself. In that case, the regular expression is
      * "/simulation1/sub1/[^/]+$" as we are only interested in changes to the objects registered under this key, so minimally
      * one character after the key that cannot be a forward slash, as that would indicate a subcontext.</li>
      * <li><b>LEVEL_OBJECT_SCOPE</b>: Suppose we are interested in changes to the objects registered <i>directly</i> under
      * "/simulation1/sub1", including the "/simulation1/sub1" context itself. In that case, the regular expression is
      * "/simulation1/sub1(/[^/]*$)?" as we are interested in changes to the objects directly registered under this key, so
      * minimally one character after the key that cannot be a forward slash. The context "sub1" itself is also included, with or
      * without a forward slash at the end.</li>
      * <li><b>SUBTREE_SCOPE</b>: Suppose we are interested in changes to the objects registered in the total subtree under
      * "/simulation1/sub1", including the "/simulation1/sub1" context itself. In that case, the regular expression is
      * "/simulation1/sub1(/.*)?". The context "sub1" itself is also included, with or without a forward slash at the end.</li>
      * </ul>
      * @param absolutePath the path for which the key has to be made. The path can point to an object or a subcontext
      * @param contextScope the scope for which the key has to be made
      * @return a concatenation of the path, a hash (#) and the context scope
      */
     protected String makeRegex(final String absolutePath, final ContextScope contextScope)
     {
         String key = absolutePath;
         if (key.endsWith("/"))
         {
             key = key.substring(0, key.length() - 1);
         }
         switch (contextScope)
         {
             case LEVEL_SCOPE:
                 key += "/[^/]+$";
                 break;
 
             case LEVEL_OBJECT_SCOPE:
                 key += "(/[^/]*$)?";
                 break;
 
             case SUBTREE_SCOPE:
                 key += "(/.*)?";
                 break;
 
             default:
                 break;
         }
         return key;
     }
 
     /**
      * Add a listener for the provided scope as strong reference to the BEGINNING of a queue of listeners.
      * @param listener the listener which is interested at events of eventType.
      * @param absolutePath the absolute path of the context or object to subscribe to
      * @param contextScope the part of the tree that the listener is aimed at (current node, current node and keys, subtree).
      * @return the success of adding the listener. If a listener was already added false is returned.
      * @throws NameNotFoundException when the absolutePath could not be found in the parent context, or when an intermediate
      *             context does not exist
      * @throws InvalidNameException when the scope is OBJECT_SCOPE, but the key points to a (sub)context
      * @throws NotContextException when the scope is LEVEL_SCOPE, OBJECT_LEVEL_SCOPE or SUBTREE_SCOPE, and the key points to an
      *             ordinary object
      * @throws NamingException as an overarching exception for context errors
      * @throws NullPointerException when one of the arguments is null
      */
     public boolean addListener(final EventListener listener, final String absolutePath, final ContextScope contextScope)
             throws NameNotFoundException, InvalidNameException, NotContextException, NamingException, NullPointerException
     {
         return addListener(listener, absolutePath, contextScope, LocalEventProducer.FIRST_POSITION, ReferenceType.STRONG);
     }
 
     /**
      * Add a listener for the provided scope to the BEGINNING of a queue of listeners.
      * @param listener the listener which is interested at events of eventType.
      * @param absolutePath the absolute path of the context or object to subscribe to
      * @param contextScope the part of the tree that the listener is aimed at (current node, current node and keys, subtree).
      * @param referenceType whether the listener is added as a strong or as a weak reference.
      * @return the success of adding the listener. If a listener was already added false is returned.
      * @throws NameNotFoundException when the absolutePath could not be found in the parent context, or when an intermediate
      *             context does not exist
      * @throws InvalidNameException when the scope is OBJECT_SCOPE, but the key points to a (sub)context
      * @throws NotContextException when the scope is LEVEL_SCOPE, OBJECT_LEVEL_SCOPE or SUBTREE_SCOPE, and the key points to an
      *             ordinary object
      * @throws NamingException as an overarching exception for context errors
      * @throws NullPointerException when one of the arguments is null
      */
     public boolean addListener(final EventListener listener, final String absolutePath, final ContextScope contextScope,
             final ReferenceType referenceType)
             throws NameNotFoundException, InvalidNameException, NotContextException, NamingException, NullPointerException
     {
         return addListener(listener, absolutePath, contextScope, LocalEventProducer.FIRST_POSITION, referenceType);
     }
 
     /**
      * Add a listener for the provided scope as strong reference to the specified position of a queue of listeners.
      * @param listener the listener which is interested at events of eventType.
      * @param absolutePath the absolute path of the context or object to subscribe to
      * @param contextScope the part of the tree that the listener is aimed at (current node, current node and keys, subtree).
      * @param position the position of the listener in the queue.
      * @return the success of adding the listener. If a listener was already added, or an illegal position is provided false is
      *         returned.
      * @throws NameNotFoundException when the absolutePath could not be found in the parent context, or when an intermediate
      *             context does not exist
      * @throws InvalidNameException when the scope is OBJECT_SCOPE, but the key points to a (sub)context
      * @throws NotContextException when the scope is LEVEL_SCOPE, OBJECT_LEVEL_SCOPE or SUBTREE_SCOPE, and the key points to an
      *             ordinary object
      * @throws NamingException as an overarching exception for context errors
      * @throws NullPointerException when one of the arguments is null
      */
     public boolean addListener(final EventListener listener, final String absolutePath, final ContextScope contextScope,
             final int position)
             throws NameNotFoundException, InvalidNameException, NotContextException, NamingException, NullPointerException
     {
         return addListener(listener, absolutePath, contextScope, position, ReferenceType.STRONG);
     }
 
     /**
      * Add a listener for the provided scope to the specified position of a queue of listeners.
      * @param listener which is interested at certain events,
      * @param absolutePath the absolute path of the context or object to subscribe to
      * @param contextScope the part of the tree that the listener is aimed at (current node, current node and keys, subtree).
      * @param position the position of the listener in the queue
      * @param referenceType whether the listener is added as a strong or as a weak reference.
      * @return the success of adding the listener. If a listener was already added or an illegal position is provided false is
      *         returned.
      * @throws InvalidNameException when the path does not start with a slash
      * @throws NullPointerException when one of the arguments is null
      */
     public boolean addListener(final EventListener listener, final String absolutePath, final ContextScope contextScope,
             final int position, final ReferenceType referenceType) throws InvalidNameException, NullPointerException
     {
         Throw.when(listener == null, NullPointerException.class, "listener cannot be null");
         Throw.when(absolutePath == null, NullPointerException.class, "absolutePath cannot be null");
         Throw.when(contextScope == null, NullPointerException.class, "contextScope cannot be null");
         Throw.when(referenceType == null, NullPointerException.class, "referenceType cannot be null");
         Throw.when(!absolutePath.startsWith("/"), InvalidNameException.class, "absolute path %s does not start with '/'",
                 absolutePath);
 
         String registryKey = makeRegistryKey(absolutePath, contextScope);
         boolean added = !this.registryMap.containsKey(registryKey);
         String regex = makeRegex(absolutePath, contextScope);
         PatternListener patternListener = new PatternListener(Pattern.compile(regex), listener);
         this.regExpListenerMap.put(registryKey, patternListener);
         this.registryMap.put(registryKey, patternListener);
         return added;
     }
 
     /**
      * Remove the subscription of a listener for the provided scope for a specific event.
      * @param listener which is no longer interested.
      * @param absolutePath the absolute path of the context or object to subscribe to
      * @param contextScope ContextScope;the scope which is of no interest any more.
      * @return the success of removing the listener. If a listener was not subscribed false is returned.
      * @throws InvalidNameException when the path does not start with a slash
      * @throws NullPointerException when one of the arguments is null
      */
     public boolean removeListener(final EventListener listener, final String absolutePath, final ContextScope contextScope)
             throws InvalidNameException, NullPointerException
     {
         Throw.when(listener == null, NullPointerException.class, "listener cannot be null");
         Throw.when(absolutePath == null, NullPointerException.class, "absolutePath cannot be null");
         Throw.when(contextScope == null, NullPointerException.class, "contextScope cannot be null");
         Throw.when(!absolutePath.startsWith("/"), InvalidNameException.class, "absolute path %s does not start with '/'",
                 absolutePath);
 
         String registryKey = makeRegistryKey(absolutePath, contextScope);
         boolean removed = this.registryMap.containsKey(registryKey);
         this.regExpListenerMap.remove(registryKey);
         this.registryMap.remove(registryKey);
         return removed;
     }
 
     /**
      * Pair of regular expression pattern and event listener.
      * <p>
      * Copyright (c) 2020-2025 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
      * See for project information <a href="https://simulation.tudelft.nl/dsol/manual/" target="_blank">DSOL Manual</a>. The
      * DSOL project is distributed under a three-clause BSD-style license, which can be found at
      * <a href="https://simulation.tudelft.nl/dsol/docs/latest/license.html" target="_blank">
      * https://simulation.tudelft.nl/dsol/docs/latest/license.html</a>.
      * </p>
      * @author <a href="https://github.com/averbraeck" target="_blank">Alexander Verbraeck</a>
      */
     public class PatternListener
     {
         /** the compiled regular expression pattern. */
         private final Pattern pattern;
 
         /** the event listener for this pattern. */
         private final EventListener listener;
 
         /**
          * Construct a pattern - listener pair.
          * @param pattern the compiled pattern
          * @param listener the registered listener for this pattern
          */
         public PatternListener(final Pattern pattern, final EventListener listener)
         {
             super();
             this.pattern = pattern;
             this.listener = listener;
         }
 
         /**
          * return the compiled pattern.
          * @return the compiled pattern
          */
         public Pattern getPattern()
         {
             return this.pattern;
         }
 
         /**
          * Return the registered listener for this pattern.
          * @return the registered listener for this pattern
          */
         public EventListener getListener()
         {
             return this.listener;
         }
     }
 }