/*
This program plays paper, scissors, rock with the
user with the computer making its choices randomly.
The program runs in a loop while the user types yes.
Example of do .. while loop and switch statements
*/
import java.util.*;

public class PaperScissorsRock
{
   // constants for paper, scissors, and rock
   private final static int SCISSORS = 0;
   private final static int ROCK = 1;
   private final static int PAPER = 2;
   
   public static void main(String[] args)
   {    
      Scanner kbd = new Scanner(System.in);
      Random rand = new Random();       // for computer's choice
      int user = 0, computer = 0;       // the players
      String response;
      do
         {
            // get user's choice of p, s, r
            System.out.print("Choose P, S, R:  ");
            String choice = kbd.nextLine();
            // translate into constant integers
            if (choice.equalsIgnoreCase("s"))
               user = SCISSORS;         
            else if (choice.equalsIgnoreCase("r"))
               user = ROCK;             
            else if (choice.equalsIgnoreCase("p"))
               user = PAPER;            
                   // computer makes random choice
            computer = rand.nextInt(3);
            System.out.print("Computer chooses ");
            System.out.println(PSR(computer));
                    // determine whether user or computer wins
            switch (user - computer)
               {
               case 0 :                                 
                  System.out.println("Tie");
                  break;
               case 1 :
               case -2 :
                  System.out.println("You win");
                  break;
               case 2 :
               case -1 :
                  System.out.println("Computer wins");
                  break;
               }
            System.out.print("Play again (y/n)?  ");
            response = kbd.nextLine();
                    // loop while user answers yes
                         // note: user input should really be validated here
         } while(response.equalsIgnoreCase("y") ||
                 response.equalsIgnoreCase("yes"));
   }    

   private static String PSR(int i)
   {
      // translate constant int code into string
      String str;
      switch (i)
         {
         case PAPER :
            str = "paper"; break;
         case SCISSORS :
            str = "scissors"; break;
         case ROCK :
            str = "rock"; break;
         default :
            str = "";
         }
      return str;
   }
}