package org.djutils.event.util;
   
   import java.io.Serializable;
   import java.util.Collection;
   import java.util.Map;
   import java.util.Set;
   
   import org.djutils.event.EventProducer;
   import org.djutils.event.EventType;
  import org.djutils.event.IdProvider;
  import org.djutils.exceptions.Throw;
  import org.djutils.metadata.MetaData;
  import org.djutils.metadata.ObjectDescriptor;
  
  /**
   * The Event producing map provides a map to which one can subscribe interest in entry changes. This class does not keep track
   * of changes which take place indirectly. One is for example not notified on <code>map.iterator.remove()</code>. A listener
   * must subscribe to the iterator, key set, etc. individually.
   * <p>
   * Copyright (c) 2002-2022 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
   * for project information <a href="https://djutils.org" target="_blank"> https://djutils.org</a>. The DJUTILS project is
   * distributed under a three-clause BSD-style license, which can be found at
   * <a href="https://djutils.org/docs/license.html" target="_blank"> https://djutils.org/docs/license.html</a>. This class was
   * originally part of the DSOL project, see <a href="https://simulation.tudelft.nl/dsol/manual" target="_blank">
   * https://simulation.tudelft.nl/dsol/manual</a>.
   * </p>
   * @author <a href="https://www.linkedin.com/in/peterhmjacobs">Peter Jacobs </a>
   * @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @param <K> the key type
   * @param <V> the value type
   */
  public class EventProducingMap<K, V> extends EventProducer implements Map<K, V>
  {
      /** The default serial version UID for serializable classes. */
      private static final long serialVersionUID = 20191230L;
  
      /** OBJECT_ADDED_EVENT is fired on new entries. */
      public static final EventType OBJECT_ADDED_EVENT =
              new EventType("OBJECT_ADDED_EVENT", new MetaData("Size of the map after add", "Size of the map",
                      new ObjectDescriptor("Size of the map after add", "Size of the map", Integer.class)));
  
      /** OBJECT_REMOVED_EVENT is fired on removal of entries. */
      public static final EventType OBJECT_REMOVED_EVENT =
              new EventType("OBJECT_REMOVED_EVENT", new MetaData("Size of the map after remove", "Size of the map",
                      new ObjectDescriptor("Size of the map after remove", "Size of the map", Integer.class)));
  
      /** OBJECT_CHANGED_EVENT is fired on change of one or more entries. */
      public static final EventType OBJECT_CHANGED_EVENT =
              new EventType("OBJECT_CHANGED_EVENT", new MetaData("Size of the map after change", "Size of the map",
                      new ObjectDescriptor("Size of the map after change", "Size of the map", Integer.class)));
  
      /** the parent map. */
      private final Map<K, V> parent;
  
      /** the function that produces the id by which the EventProducer can be identified. */
      private final IdProvider sourceIdProvider;
  
      /**
       * constructs a new EventProducingMap.
       * @param parent Map&lt;K,V&gt;; the embedded map.
       * @param sourceId Serializable; the id by which the EventProducer can be identified by the EventListener
       */
      public EventProducingMap(final Map<K, V> parent, final Serializable sourceId)
      {
          this(parent, new IdProvider()
          {
              /** */
              private static final long serialVersionUID = 20200119L;
  
              @Override
              public Serializable id()
              {
                  return sourceId;
              }
          });
      }
  
      /**
       * Constructs a new EventProducingMap.
       * @param parent Map&lt;K, V&gt;; the parent map.
       * @param sourceIdProvider IdProvider; the function that produces the id by which the EventProducer can be identified by the
       *            EventListener
       */
      public EventProducingMap(final Map<K, V> parent, final IdProvider sourceIdProvider)
      {
          Throw.whenNull(parent, "parent cannot be null");
          Throw.whenNull(sourceIdProvider, "sourceIdprovider cannot be null");
          this.parent = parent;
          this.sourceIdProvider = sourceIdProvider;
      }
  
      /** {@inheritDoc} */
      @Override
      public Serializable getSourceId()
      {
          return this.sourceIdProvider.id();
      }
  
      /** {@inheritDoc} */
     @Override
     public int size()
     {
         return this.parent.size();
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean isEmpty()
     {
         return this.parent.isEmpty();
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean containsKey(final Object key)
     {
         return this.parent.containsKey(key);
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean containsValue(final Object value)
     {
         return this.parent.containsValue(value);
     }
 
     /** {@inheritDoc} */
     @Override
     public V get(final Object key)
     {
         return this.parent.get(key);
     }
 
     /** {@inheritDoc} */
     @Override
     public V put(final K key, final V value)
     {
         int nr = this.parent.size();
         V result = this.parent.put(key, value);
         if (nr != this.parent.size())
         {
             this.fireEvent(OBJECT_ADDED_EVENT, this.parent.size());
         }
         else
         {
             this.fireEvent(OBJECT_CHANGED_EVENT, this.parent.size());
         }
         return result;
     }
 
     /** {@inheritDoc} */
     @Override
     public V remove(final Object key)
     {
         int nr = this.parent.size();
         V result = this.parent.remove(key);
         if (nr != this.parent.size())
         {
             this.fireEvent(OBJECT_REMOVED_EVENT, this.parent.size());
         }
         return result;
     }
 
     /** {@inheritDoc} */
     @Override
     public void putAll(final Map<? extends K, ? extends V> map)
     {
         int nr = this.parent.size();
         this.parent.putAll(map);
         if (nr != this.parent.size())
         {
             this.fireEvent(OBJECT_ADDED_EVENT, this.parent.size());
         }
         else
         {
             if (!map.isEmpty())
             {
                 this.fireEvent(OBJECT_CHANGED_EVENT, this.parent.size());
             }
         }
     }
 
     /** {@inheritDoc} */
     @Override
     public void clear()
     {
         int nr = this.parent.size();
         this.parent.clear();
         if (nr != this.parent.size())
         {
             this.fireEvent(OBJECT_REMOVED_EVENT, this.parent.size());
         }
     }
 
     /** {@inheritDoc} */
     @Override
     public Set<K> keySet()
     {
         return this.parent.keySet();
     }
 
     /** {@inheritDoc} */
     @Override
     public Collection<V> values()
     {
         return this.parent.values();
     }
 
     /** {@inheritDoc} */
     @Override
     public Set<Map.Entry<K, V>> entrySet()
     {
         return this.parent.entrySet();
     }
 }