/*
  Author:  James Tam
  Version: Feb. 1, 2021

  Learning objectives: understanding the keywords static (class memory or method) 
  and final (unchanging constants). Reviewing the difference between a reference
  and an object (hobbes appears to have changed inside of the main method).

*/


public class Cat
{
     //Class constants that specify the mood of a cat.
     public static final int SLEEPY = 1;
     public static final int GRUMPY = 2;
     public static final int PLAYFUL = 3;

    //Class constant to specify the sensible maximum number of cats.
     public static final int MAX_POPULATION = 3;

     //Class variable that trackes the total population.
     private static int population = 0;

     //Instance attribute: each cat has it's own mood.
     private int mood;

     public Cat ()
     {
         setMood(GRUMPY);
         increasePopulation();
     }

     public Cat (int aMood)
     {
         setMood(aMood);
         increasePopulation();
     }

     public String whatMood()
     {
          String moodDescription = null;
          switch (mood)
          {
              case GRUMPY:
                  moodDescription = "Grumpy";
                  break;

              case SLEEPY:
                  moodDescription = "Sleepy";
                  break;

              case PLAYFUL:
                  moodDescription = "Wanting to play :P";
          }
          return(moodDescription);
     }

     //Needs to be class specific and not instance specific otherwise there would
     //be no way to check the population if there were no cat.s
     public static int getPopulation()
     {
          return(population);
     }

     //Private because the population should only be changed when a new
     //cat created (constructor called).
     private void increasePopulation()
     {
         population++;
         if (population > MAX_POPULATION)
         {
             System.out.println("<< Error: Max. cat population of " +
               MAX_POPULATION + " has been exceeded >>");
         }
     }

     public void setMood(int newMood)
     {
         if ((newMood < SLEEPY) || (newMood > PLAYFUL))
         {
             System.out.println("Mood is not one of the valid values (" 
               + SLEEPY + "-" + PLAYFUL + ")");
             mood = SLEEPY;
         }
         else
         {
             mood = newMood;
         }
     }

}