/**
 * Holds a trivia or quiz question, a list of possible answers,
 * and the index of the correct answer.  Indexes passed as parameters
 * to Question methods start indexing at 0.
 * 
 * @author Zach Tomaszewski
 * @version Nov 21, 2007
 */
public class Question {
  
  protected String question;
  protected String[] answers;
  protected int correctIndex;  //index of correct answer in answers array

  
  /**
   * Creates a new Question.
   * 
   * @param question  The question.
   * @param answers   A list of answers.
   * @param correct   The index of the correct answer in answers;
   *                  must be >= 0 and < answers.length
   *                  
   * @throws IndexOutOfBoundsException   If correct index is out of range.
   * @throws NullPointerException        If answer list is null.
   */
  public Question(String question, String[] answers, int correct) 
                 throws IllegalArgumentException {
    
    if (correct < 0 || correct >= answers.length) {
      throw new IndexOutOfBoundsException("Correct answer index out of range.");
    }      
    this.question = question;
    this.answers = answers;
    this.correctIndex = correct;
  }
  
  
  /**
   * Returns the index of the correct answer.
   */
  public int getCorrect() {
    return this.correctIndex;
  }
  
  /**
   * Returns whether the given answerIndex corresponds to the correct
   * answer to this question.
   * 
   * @throws IndexOutOfBoundsException  If answerIndex is not within range
   *                                    of a possible answer.
   */
  public boolean isCorrect(int answerIndex) throws IndexOutOfBoundsException {
    if (answerIndex < 0 || answerIndex >= this.answers.length) {
      throw new IndexOutOfBoundsException("Given answer index out of range.");
    }else {
      return (answerIndex == this.correctIndex);
    }
  }
  
  /**
   * Returns a string representation of this question, 
   * which displays a question followed by a numbered list
   * of answers.  <i>Note that displayed numbering starts at 1.</i>
   * <p>
   * Example:
   * <pre>
   * Question.
   * 1. first answer
   * 2. second answer
   * 3. third answer
   * </pre>
   */
  public String toString() {
    String result = this.question + "\n";
    for (int i = 0; i < answers.length; i++) {
      result += (i + 1) + ". " + answers[i] + "\n";
    }
    return result;
  }
}