import javax.swing.*;

/**
 * A game for guessing a number, where the user is told the range the
 * solution is in based on their guesses.
 */
public class GuessingRange {

  /** The number to be guessed */
  private int solution;

  /**
   * A GuessingGame with solution n.
   * @param n the number to be guessed.
   */
  public GuessingRange(int n) {
    this.solution= n;
  }

  /**
   * Play the guessing game. Continually prompt the user for a guess until
   * they guess the solution. Let them know whether their guesses are too
   * high or too low, and also tell them the range the solution is in (based
   * on their previous guesses).
   */
  public void play() {
    // The beginning of the message where the user guesses too low.
    final String LOW_MESSAGE= "Your guess was too low. " + 
      "You know that the number is in the range\n";

    // The beginning of the message where the user guesses too high.
    final String HIGH_MESSAGE= "Your guess was too high. " + 
      "You know that the number is in the range\n";

    // The end of the message.
    final String MESSAGE_END= ", inclusive. Guess again.";

    String upper= ""; // The upper end of the range the solution is in.
    String lower= ""; // The lower end of the range the solution is in.
    String message= "Guess an integer."; // The message for the user.

    // The current guess.
    int guess= Integer.parseInt(JOptionPane.showInputDialog(message));
    int numGuesses= 1; // The number of times the user has guessed.

    // Keep going until the user guesses correctly.
    while (guess != this.solution) {

      // Is the user guess too high?
      if (guess > this.solution) {

        if (upper.equals("") || guess <= Integer.parseInt(upper)) {
          upper = "" + (guess - 1);
        }
        message= HIGH_MESSAGE + lower + ".." + upper + MESSAGE_END;

      } else { // The user guess is low.

        if (lower.equals("") || guess >= Integer.parseInt(lower)) {
          lower = "" + (guess + 1);
        }
        message= LOW_MESSAGE + lower + ".." + upper + MESSAGE_END;

      }

      guess= Integer.parseInt(JOptionPane.showInputDialog(message));
      numGuesses++;
    }

    message= "You're right! You used " + numGuesses + " guesses.";
    JOptionPane.showMessageDialog(null, message);
  }
}