package umontreal.iro.lecuyer.randvar;
import umontreal.iro.lecuyer.probdist.DiscreteDistributionInt;
import umontreal.iro.lecuyer.rng.RandomStream;


/**
 * This class permits one to create a discrete univariate
 * distribution using UNURAN via its string API.
 * 
 */
public class UnuranDiscreteInt extends RandomVariateGenInt {

   private RandUnuran unuran = new RandUnuran();


   /**
    * Same as {@link #UnuranDiscreteInt UnuranDiscreteInt} (s, s, genStr).
    * 
    */
   public UnuranDiscreteInt (RandomStream s, String genStr) {
      if (s == null)
         throw new IllegalArgumentException ("mainStream must not be null.");

      unuran.mainStream = unuran.auxStream = s;
      unuran.init (genStr);
      if (!unuran.isDiscrete()) {
         unuran.close();
         throw new IllegalArgumentException ("not a discrete distribution");
      }
   }


   /**
    * Constructs a new discrete random number generator using
    *   the UNURAN generator specification string genStr,
    *   main stream s, and auxiliary stream aux.
    * 
    */
   public UnuranDiscreteInt (RandomStream s, RandomStream aux,
                             String genStr) {
      if (s == null)
         throw new IllegalArgumentException ("mainStream must not be null.");
      if (aux == null)
         throw new IllegalArgumentException ("auxStream must not be null.");

      unuran.mainStream = s;
      unuran.auxStream = aux;
      unuran.init (genStr);
      if (!unuran.isDiscrete()) {
         unuran.close();
         throw new IllegalArgumentException ("not a discrete distribution");
      }
   }


   public int nextInt() {
      if (unuran.nativeParams == 0)
         throw new IllegalStateException();
      return unuran.getRandDisc (unuran.mainStream.nextDouble(), unuran.nativeParams);
   }

   public void nextArrayOfInt (int[] v, int start, int n) {
      if (v == null || start < 0 || n < 0 || (start+n) > v.length)
         throw new IllegalArgumentException();
      if (unuran.unifArray == null || unuran.unifArray.length < n)
         unuran.unifArray = new double[n];
      if (unuran.mainStream != unuran.auxStream &&
         (unuran.unifAuxArray == null || unuran.unifAuxArray.length < n))
         unuran.unifAuxArray = new double[n];
      unuran.getRandDiscArray (unuran.nativeParams, unuran.unifArray,
                        unuran.unifAuxArray, v, start, n);
   }

   protected void finalize() {
      unuran.close();
   }

   public DiscreteDistributionInt getDistribution() { return null; }

   public RandomStream getStream() { return unuran.mainStream; }

   /**
    * Returns the auxiliary random number stream.
    * 
    */
   public RandomStream getAuxStream() {
      return unuran.auxStream;
   }
}