package umontreal.iro.lecuyer.rng;

/**
 * This exception is thrown when a random stream factory cannot instantiate a stream
 * on a call to its {@link umontreal.iro.lecuyer.rng.RandomStreamFactory#newInstance(()) newInstance} method.
 * 
 */
public class RandomStreamInstantiationException extends RuntimeException {
   private RandomStreamFactory factory;


   /**
    * Constructs a new random stream instantiation exception with
    *  no message, no cause, and thrown by the given factory.
    * 
    * @param factory the random stream factory which thrown the exception.
    * 
    * 
    */
   public RandomStreamInstantiationException (RandomStreamFactory factory) {
      super();
      this.factory = factory;
   }


   /**
    * Constructs a new random stream instantiation exception with
    *  the given message, no cause, and concerning factory.
    * 
    * @param factory the random stream factory concerned by the exception.
    * 
    *    @param message the error message describing the exception.
    * 
    * 
    */
   public RandomStreamInstantiationException (RandomStreamFactory factory,
                                         String message) {
      super (message);
      this.factory = factory;
   }


   /**
    * Constructs a new random stream instantiation exception with
    *  no message, the given cause, and concerning factory.
    * 
    * @param factory the random stream factory concerned by the exception.
    * 
    *    @param cause the cause of the exception.
    * 
    * 
    */
   public RandomStreamInstantiationException (RandomStreamFactory factory,
                                         Throwable cause) {
      super (cause);
      this.factory = factory;
   }


   /**
    * Constructs a new random stream instantiation exception with
    *  the given message, the supplied cause, 
    *  and concerning factory.
    * 
    * @param factory the random stream factory concerned by the exception.
    * 
    *    @param message the error message describing the exception.
    * 
    *    @param cause the cause of the exception.
    * 
    * 
    */
   public RandomStreamInstantiationException (RandomStreamFactory factory,
                                         String message, Throwable cause) {
      super (message, cause);
      this.factory = factory;
   }


   /**
    * Returns the random stream factory concerned by this exception.
    * 
    * @return the random stream factory concerned by this exception.
    * 
    */
   public RandomStreamFactory getRandomStreamFactory() {
      return factory;
   }


   /**
    * Returns a short description of the exception.
    *  If {@link #getRandomStreamFactory(()) getRandomStreamFactory} returns null,
    *  this calls super.toString. Otherwise, the
    *  result is the concatenation of:
    * 
    *   a) the name of the actual class of the exception;
    * 

    * b) the string ": For random stream factory ";
    * 

    * c) the result of {@link #getRandomStreamFactory(()) getRandomStreamFactory}.toString();
    * 

    * d) if {@link java.lang.Throwable#getMessage(()) getMessage} is non-null,
    *      ", " followed by the result of 
    *      {@link java.lang.Throwable#getMessage(()) getMessage}.
    * 
    * @return a string representation of the exception.
    */
   public String toString() {
      if (factory == null)
         return super.toString();

      StringBuffer sb = new StringBuffer (getClass().getName());
      sb.append (": For random stream factory ");
      sb.append (factory.toString());
      String msg = getMessage();
      if (msg != null)
         sb.append (", ").append (msg);
      return sb.toString();
   }
}