import java.util.Random; 

/* An instance of this class represents a (fair) coin that is suitable
** for simulating a sequence of coin tosses.
**
** Author: R. McCloskey
** Date: January 2024
*/
public class Coin {

   // instance variables
   // ------------------

   protected boolean isHeads;   // true if HEADS is "showing"
   protected Random rand;       // for producing pseudo-random numbers that
                                // simulate coin tosses
  

   // constructors
   // ------------

   /* Establishes this coin as one that is showing HEADS and whose toss()
   ** method uses a pseudo-random number generator seeded by the given value.
   */
   public Coin(int seed) {
      rand = new Random(seed);
      isHeads = true;
   }

   /* Establishes this coin as one that is showing HEADS and whose toss()
   ** method uses a pseudo-random number generator seeded by a number that
   ** is itself generated pseudo-randomly.
   */
   public Coin() { this((int)(20000 * Math.random())); }


   // observers
   // ---------

   /* Reports whether or not this coin is showing HEADS.
   */
   public boolean isHeads() { return isHeads; }

   /* Reports whether or not this coin is showing TAILS.
   */
   public boolean isTails() { return !isHeads(); }

   /* Returns a string indicating which face this coin is showing.
   */
   public String toString() { 
      String nameOfClass = this.getClass().getName();
      String face = isHeads() ? "HEADS" : "TAILS";
      return String.format("Class: %s; Face Showing: %s", nameOfClass, face);
   }


   // mutator
   // -------

   /* Tosses this coin, producing each of the two possible results
   ** with equal probability.
   */
   public void toss() { 
      isHeads = rand.nextDouble() < (1.0 / 2.0);

      // alternative (but does not produce same result each time):
      //isHeads = rand.nextBoolean(); 
   }

}