package org.djutils.stats.summarizers.event;
   
   import java.io.Serializable;
   
   import org.djutils.event.Event;
   import org.djutils.event.EventInterface;
   import org.djutils.event.EventListenerInterface;
   import org.djutils.event.EventProducer;
   import org.djutils.exceptions.Throw;
  import org.djutils.stats.summarizers.WeightedTally;
  import org.djutils.stats.summarizers.WeightedTallyInterface;
  
  /**
   * The EventBasedWeightedTally class defines a time-weighted tally that can be notified with weights and values using the
   * EventListenerInterface. It also produces events when values are tallied and when the tally is initialized.
   * <p>
   * Copyright (c) 2002-2021 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
   * for project information <a href="https://simulation.tudelft.nl/" target="_blank"> https://simulation.tudelft.nl</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/3.0/license.html" target="_blank">
   * https://simulation.tudelft.nl/dsol/3.0/license.html</a>. <br>
   * @author <a href="https://www.tudelft.nl/averbraeck" target="_blank"> Alexander Verbraeck</a>
   * @author <a href="https://www.tudelft.nl/staff/p.knoppers/">Peter Knoppers</a>
   */
  public class EventBasedWeightedTally extends EventProducer implements EventListenerInterface, WeightedTallyInterface
  {
      /** */
      private static final long serialVersionUID = 20200228L;
  
      /** the wrapped WeightedTally. */
      private final WeightedTally wrappedWeightedTally;
  
      /**
       * Construct a new WeightedTally with a description.
       * @param description String; the description of this WeightedTally
       */
      public EventBasedWeightedTally(final String description)
      {
          this.wrappedWeightedTally = new WeightedTally(description);
      }
  
      /** {@inheritDoc} */
      @Override
      public Serializable getSourceId()
      {
          return this;
      }
  
      /** {@inheritDoc} */
      @Override
      public final String getDescription()
      {
          return this.wrappedWeightedTally.getDescription();
      }
  
      /** {@inheritDoc} */
      @Override
      public final double getMax()
      {
          return this.wrappedWeightedTally.getMax();
      }
  
      /** {@inheritDoc} */
      @Override
      public final double getMin()
      {
          return this.wrappedWeightedTally.getMin();
      }
  
      /** {@inheritDoc} */
      @Override
      public final long getN()
      {
          return this.wrappedWeightedTally.getN();
      }
  
      /** {@inheritDoc} */
      @Override
      public final double getWeightedSampleMean()
      {
          return this.wrappedWeightedTally.getWeightedSampleMean();
      }
  
      /** {@inheritDoc} */
      @Override
      public final double getWeightedSampleStDev()
      {
          return this.wrappedWeightedTally.getWeightedSampleStDev();
      }
  
      /** {@inheritDoc} */
      @Override
      public final double getWeightedPopulationStDev()
      {
          return this.wrappedWeightedTally.getWeightedPopulationStDev();
      }
  
      /** {@inheritDoc} */
      @Override
     public final double getWeightedSampleVariance()
     {
         return this.wrappedWeightedTally.getWeightedSampleVariance();
     }
 
     /** {@inheritDoc} */
     @Override
     public final double getWeightedPopulationVariance()
     {
         return this.wrappedWeightedTally.getWeightedPopulationVariance();
     }
 
     /** {@inheritDoc} */
     @Override
     public final double getWeightedSum()
     {
         return this.wrappedWeightedTally.getWeightedSum();
     }
 
     /** {@inheritDoc} */
     @Override
     public void initialize()
     {
         this.wrappedWeightedTally.initialize();
         fireEvent(new Event(StatisticsEvents.INITIALIZED_EVENT, this, null));
     }
 
     /** {@inheritDoc} */
     @Override
     public void notify(final EventInterface event)
     {
         Throw.when(!(event.getContent() instanceof Object[]), IllegalArgumentException.class,
                 "WeightedTally.notify: Content should be Object[] {weight, value}");
         Object[] content = (Object[]) event.getContent();
         Throw.when(content.length != 2, IllegalArgumentException.class,
                 "WeightedTally.notify: Content should be Object[] {weight, value}");
         Throw.when(!(content[0] instanceof Number), IllegalArgumentException.class,
                 "WeightedTally.notify: Weight (Content[0]) should be a Number");
         Throw.when(!(content[1] instanceof Number), IllegalArgumentException.class,
                 "WeightedTally.notify: Value (Content[1]) should be a Number");
         double weight = ((Number) content[0]).doubleValue();
         double value = ((Number) content[1]).doubleValue();
         ingest(weight, value);
     }
 
     /**
      * Process one observed weighted value.
      * @param weight double; the weight of the value to process
      * @param value double; the value to process
      * @return double; the value
      */
     public double ingest(final double weight, final double value)
     {
         this.wrappedWeightedTally.ingest(weight, value);
         if (hasListeners())
         {
             fireEvent(new Event(StatisticsEvents.WEIGHTED_OBSERVATION_ADDED_EVENT, this, new Object[] {weight, value}));
             fireEvents();
         }
         return value;
     }
 
     /**
      * Method that can be overridden to fire own events or additional events when ingesting an observation.
      */
     protected void fireEvents()
     {
         fireEvent(new Event(StatisticsEvents.N_EVENT, this, getN()));
         fireEvent(new Event(StatisticsEvents.MIN_EVENT, this, getMin()));
         fireEvent(new Event(StatisticsEvents.MAX_EVENT, this, getMax()));
         fireEvent(new Event(StatisticsEvents.WEIGHTED_POPULATION_MEAN_EVENT, this, getWeightedPopulationMean()));
         fireEvent(new Event(StatisticsEvents.WEIGHTED_POPULATION_VARIANCE_EVENT, this, getWeightedPopulationVariance()));
         fireEvent(new Event(StatisticsEvents.WEIGHTED_POPULATION_STDEV_EVENT, this, getWeightedPopulationStDev()));
         fireEvent(new Event(StatisticsEvents.WEIGHTED_SUM_EVENT, this, getWeightedSum()));
         fireEvent(new Event(StatisticsEvents.WEIGHTED_SAMPLE_MEAN_EVENT, this, getWeightedSampleMean()));
         fireEvent(new Event(StatisticsEvents.WEIGHTED_SAMPLE_VARIANCE_EVENT, this, getWeightedSampleVariance()));
         fireEvent(new Event(StatisticsEvents.WEIGHTED_SAMPLE_STDEV_EVENT, this, getWeightedSampleStDev()));
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public String toString()
     {
         return this.wrappedWeightedTally.toString();
     }
 
 }