package nl.tudelft.simulation.jstats.distributions;
   
   import org.djutils.exceptions.Throw;
   
   import nl.tudelft.simulation.jstats.distributions.empirical.DiscreteEmpiricalDistribution;
   import nl.tudelft.simulation.jstats.distributions.empirical.DistributionEntry;
   import nl.tudelft.simulation.jstats.streams.StreamInterface;
   
   /**
   * A discrete empirical distribution as defined on page 326 of Law & Kelton, based on an EmpiricalDistribution object.
   * <p>
   * Copyright (c) 2002-2025 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://www.linkedin.com/in/peterhmjacobs">Peter Jacobs </a>
   * @author <a href="https://github.com/averbraeck">Alexander Verbraeck</a>
   */
  public class DistEmpiricalDiscreteLong extends DistDiscrete
  {
      /** */
      private static final long serialVersionUID = 20210403L;
  
      /** the empirical distribution. */
      private final DiscreteEmpiricalDistribution empiricalDistribution;
  
      /**
       * constructs a new DistEmpirical distribution.
       * @param stream StreamInterface; the stream to use
       * @param empiricalDistribution EmpiricalDistributionInterface; the cumulative distribution to use
       * @throws IllegalArgumentException when the empirical distribution has non-integer values
       */
      public DistEmpiricalDiscreteLong(final StreamInterface stream, final DiscreteEmpiricalDistribution empiricalDistribution)
      {
          super(stream);
          // check that the values in the distribution are integer valued and we do not interpolate
          for (Number n : empiricalDistribution.getValues())
          {
              Throw.when(n instanceof Double || n instanceof Float, IllegalArgumentException.class,
                      "empirical distribution can only contain integer or long values");
          }
          this.empiricalDistribution = empiricalDistribution;
      }
  
      @Override
      public long draw()
      {
          double u = this.stream.nextDouble();
          return this.empiricalDistribution.getCeilingEntry(u).getValue().longValue();
      }
  
      @Override
      public double probability(final long observation)
      {
          DistributionEntry entry1 = this.empiricalDistribution.getFloorEntryForValue(observation);
          if (entry1 == null || entry1.getValue().longValue() != observation)
          {
              return 0.0;
          }
          double c1 = entry1.getCumulativeProbability();
          DistributionEntry entry0 = this.empiricalDistribution.getPrevEntry(c1);
          return (entry0 == null) ? c1 : c1 - entry0.getCumulativeProbability();
      }
  
  }