/* HostApplet.java
 * Ian Barland   ian@cs.rice.edu
 * 96.Dec.18     Comp210
 * The applet version of the game-show host for Trivia
 * (see http://www.owlnet.rice.edu/~comp210/Assignments/12/12.html).
 *
 * Use this file with your hw12 to put your quiz onto your own web page.
 * You don't need to change your class Judge, StringList, QandA, QandA_List.
 * However, the driver class Trivia isn't needed any more (that approach
 * didn't mesh well with the event-driven style).
 *
 * To run the quiz show as an applet on your own personal web page:
 * (1) Copy HostApplet.java to your html directory, as well as
 *     your other classes for hw12: Judge, StringList, QandA, QandA_List.
 *     (HostApplet.java resides in ~comp210/public_html/Projects/Trivia.)
 * (2) Modify HostApplet.java to personalize the questions,
 * (3) Compile the .java files to .class files, and
 * (4) Add lines
 *         <applet code = "HostApplet.class">
 *         </applet>
 *     to your web page as discussed in lab14.
 *     Note that for the applet to run, the needed .class files really do
 *     need to reside in the same directory as your .html file :-(
 *
 *  If you have a fun quiz, or spruce up this interface, let me & matthias
 *  know about it! -- ian
 */

import java.applet.Applet;
import java.awt.*;


public class HostApplet extends Applet {

  // Some variables for the HostApplet.
  // (declared private since no other objects have the right to know these.)
  //
  private Judge judge;

  private String rightMsg  = "Got it!"; // Message when player guesses right,
  private String wrongMsg  = "Nope.";                //     or guesses wrong,
  private String byebyeMsg = "Thanks for playing.";  //     or finishes.

  private TextField questionSite;       // The box containing the question
  private java.awt.List answerSite;     // The box containing list-of-answers
                /* (Note the use of the full class name, instead of just List, 
                 *  to avoid any confusion with any class List of our own.)
		 */

 
  /* HostApplet constructor
   */
  public HostApplet() {
    /* Don't do anything applet/graphics-dependent in the constructor!
     * Do such things in init(), instead.
     */

    // Formulate the list of questions
    //
    QandA_List qaList = new QandA_Null();
    qaList = addQA( qaList, "Who's on third?", "I don't know." );
    qaList = addQA( qaList, "Which came first, chicken or egg?", 
		            "dinosaur egg" );
    qaList = addQA( qaList, "A synonym for yellow", "chicken" );
    qaList = addQA( qaList, "English for 'oeuf'.", "egg" );

    judge = new Judge( qaList );
    }


  /* addQA
   * Take a list of QandA; tack a new QandA on the front.
   */
  private QandA_List addQA( QandA_List l, String q, String a ) {
    return new QandA_Cons( new QandA( q, a ), l );
    }


  /* init()
   * The Applet/window-manager initialization.
   * Here is where to do all graphical interface setup.
   */
  public void init() {
    super.init();    // call the init() for class Applet (whom we extend)

    questionSite = new TextField( 60 );            // Create the text gizmo.
    questionSite.setEditable( false );             // Customize it.
    add( questionSite );                           // Add it to the window.

    answerSite = new java.awt.List();              // Create text-list gizmo.
    answerSite.setMultipleSelections( false );     // Customize it.
    add( answerSite );                             // Add it to the window.

    // Put our answers into the answerSite, and set up initial question:
    setAnswers( judge.getAnswerList() );
    questionSite.setText( judge.nextQuestion() );
    }


  /* handleEvent
   * The heart of the applet:
   * If user is guessing at an answer, respond & pose next question.
   */
  public boolean handleEvent( Event event ) {

    if (event.target != answerSite)
      // Ignore any events besides the guessing of an answer.
      return false;

    respondTo( answerSite.getSelectedItem() );
    answerSite.deselect( answerSite.getSelectedIndex() );

    boolean carryOn = setupNextQuestion();
    if (!carryOn) {
      answerSite.clear();   // Get rid of all old questions
      System.exit(0);       // Hmm, this has no effect. How should applets exit?
      }

    return true;  // We've handled the answerSite event.
    }



  /* respondTo
   * Ask judge if "guess" was correct; praise/disparage accordingly.
   */
  private void respondTo( String guess ) {
    String response;
    if (judge.rightAnswer( guess ))
      response = rightMsg;
    else
      response = wrongMsg;
    showStatus( response );               // Show on netscape's bottom line.
    }


  /* setupNextQuestion
   * Select and display the next question.
   * Return false if the user is done or wants to quit.
   */
  private boolean setupNextQuestion() {
    String nextQ = judge.nextQuestion();
    boolean finito = nextQ.equals( "" );  // Judge's way of saying "game over"
    if (finito)
      nextQ = byebyeMsg;
    questionSite.setText( nextQ );        // Pose the new question.
    return !finito;
    }



  /* setAnswers
   * Change the list of answers.
   */ 
  public void setAnswers( StringList answers ) {
    answerSite.clear();   // Get rid of all old questions

    // Walk through list of answers, adding to answerSite.
    for ( StringList as = answers;
	  as instanceof StringCons;
	  as = ((StringCons)as).cdr ) {
      answerSite.addItem( ((StringCons)as).car );
      }
    }



  boolean debug = false;
  private void debug( String msg ) {
    if (debug) showStatus( "HostApplet debug: " + msg );
    }
 
  }