/** A class to analyze volleyball scores.
 *  @author Ian Barland
 *  @version 2006.Jan.30
 */
class VolleyballJudge {

  /** Must reach at least this score to win. */
  int GOAL = 21;              
  /** Must win by this much or more. */
  int WINNING_MARGIN = 2;

  /** Determine whether the current score indicates a game which
   * is both (a) finished, and (b) the first team won.
   * @param homeScore The score of the first team.
   * @param visitorScore The score of the second team.
   * @return true if the first team has finished defeating the second team.
   *    A return of false indicates that *either* (a) the game isn't over,
   *    or (b) the second team won.
   * For example, if vj is an instance of VolleyballJudge, <br/>
   *   vj.hasFirstTeamWon( 17,  3 ) = false <br/>
   *   vj.hasFirstTeamWon( 21,  3 ) = true  <br/>
   *   vj.hasFirstTeamWon( 21, 20 ) = false <br/>
   *   vj.hasFirstTeamWon( 23, 21 ) = true  <br/>
   *   vj.hasFirstTeamWon( 23, 25 ) = false <br/>
   */
  boolean hasFirstTeamWon( int homeScore, int visitorScore ) {
    return ((homeScore >= GOAL) && (homeScore-visitorScore >= WINNING_MARGIN));
    }
    
  /** Determine whether the current score indicates a game which
   * is both (a) finished, and (b) the first team won.
   * @param homeScore The score of the first team.
   * @param visitorScore The score of the second team.
   * @return true if the first team has finished defeating the second team.
   *    A return of false indicates that *either* (a) the game isn't over,
   *    or (b) the second team won.
   * For example, if vj is an instance of VolleyballJudge, <br/>
   *   vj.isGameOver( 17,  3 ) = false <br/>
   *   vj.isGameOver( 21,  3 ) = true  <br/>
   *   vj.isGameOver( 21, 20 ) = false <br/>
   *   vj.isGameOver( 23, 21 ) = true  <br/>
   *   vj.isGameOver( 23, 25 ) = true  <br/>
   */
  boolean isGameOver( int homeScore, int visitorScore ) {
    return (    this.hasFirstTeamWon(homeScore, visitorScore)
             || this.hasFirstTeamWon(visitorScore, homeScore) );
    }

    
  /** Compute a PR message about the result of a volleyball game,
   * suitable for printing, putting on a web page, text messaging, etc.
   * @param homeName     The name  of the first  team.
   * @param homeScore    The score of the first  team.
   * @param visitorName  The name  of the second team.
   * @param visitorScore The score of the second team.
   * @return a String stating who won (if anybody). <br/>
   * For example, if vj is an instance of VolleyballJudge, <br/>
   * vj.announceWinner( "beachfront boppers",  0, "valley volleyers",  0 )
   *    = "Game still in progress." <br/>
   * vj.announceWinner( "beachfront boppers", 21, "valley volleyers", 15 )
   *    = "beachfront boppers won!" <br/>
   * vj.announceWinner( "beachfront boppers", 15, "valley volleyers", 21 )
   *    = "valley volleyers won!" <br/>
   * vj.announceWinner( "beachfront boppers", 21, "valley volleyers", 20 )
   *    = "Game still in progress." <br/>
   * vj.announceWinner( "beachfront boppers", 25, "valley volleyers", 24 )
   *    = "Game still in progress." <br/>
   */
  String announceWinner( String homeName,    int homeScore, 
                         String visitorName, int visitorScore ) {

     String winningTeam;
     if (this.hasFirstTeamWon( homeScore, visitorScore )) {
       winningTeam = homeName;
       }
     else if (this.hasFirstTeamWon( visitorScore, homeScore )) {
       winningTeam = visitorName;
       }
     else {
       winningTeam = "announceWinner: dummy string -- this message should never be returned.";
       }
     
       
     if (this.isGameOver( homeScore, visitorScore )) {
       return winningTeam + " won!";
       }
     else {
       return "Game still in progress.";
       }
      
    /* There are a number of other good solutions:
     * (a) Checking `isGameOver` first would let you make only one further `if`
     *     test, and would omit the need for the dummy value for winningTeam.
     * (b) A 3-way if-else-if which returns a result in each branch, or
     * (c) a 3-way if-else-if which assigns to a variable "theResult" 
     *     in each branch (followed by a simple "return theResult").
     *
     * Approach (a) is probably best, even better than the solution.
     * (The solution is given as it was to keep it very clear how 
     * one 'if' was initializing a variable, and the other 'if' was 
     * returning a value, rather than slightly muddling those two parts.)
     *
     * Approaches (b) and (c) have a (very minor) amount of repeated code:
     * the concatentation of a team-name and "won!".  (If you wanted
     * two tweak the message, you'd have to tweak two places of code.)
     * On the other hand, with those two approaches, you wouldn't have
     * to rig the dummy value for winningTeam just to appease the compiler.
     */
    }

    
    
    
  // A field:
  private java.util.Random randNumGenerator = new java.util.Random();


  /** Play one game of volleyball, and say which team one.
   * @return Whether or not the first team won.
   */
  public boolean playOneGame() {
    int score1 = 0;
    int score2 = 0;

    while (! isGameOver(score1,score2) ) {
      // Play one point:
      // Choose a random team to get a point, with 50/50 odds:
      if (randNumGenerator.nextDouble() < 0.50) {
        score1 = score1 + 1;
        //System.err.println( "team1 score is now " + score1 );
        }
      else {
        score2 = score2 + 1;
        //System.err.println( "team2 score is now " + score2 );
        }
      }
      
      
    // When we reach this line, we know the game is over -- *somebody* has won!
    return this.hasFirstTeamWon(score1,score2);
    }
    
    
    
}