// Multiple Choice Applet 1.0
// Terence Tao, 2002
// 
// This applet may be freely copied and used by others.  In order to run the applet properly, you will not only need
// the class files (MultipleChoice, Question, Answer, ShuffleVector), but you will also need some quiz files, and
// an index file to list all the quiz files.  The URL of the index file must then be placed in the HTML <APPLET> code which
// calls the applet, using the "index" parameter.  The index and quiz files are plaintext.  The index file format is
// very simple: each line takes the form <quiz description> | <URL of quiz>, or of <separator> if one just wants to add a 
// non-functional separator to the index.  The quiz files have a very simple command line interface, all of the form 
// "<Command>. <arguments>".  Whitespace is ignored.  The valid commands are
//
// "Question.  <question>"  Create a new question, which becomes the current question.
// "Answer. <answer>" Create an (incorrect) answer to the current question.
// "Correct Answer. <answer>" Create a correct answer to the current question.
// "Partially Correct Answer. <answer>" Create a partially correct answer to the current question.
// "Comment. <comment>" Make a comment to a question or answer which will be displayed to the user when the question
// 	or answer is selected.
// "Value. <value>" Set the points value for the current question and all later questions (Default 10)
// "Correctness. <value>" Set the correctness (out of 10) of the current answer (Default 0 for incorrect answers,
// 	5 for partially correct, 10 for correct)
// "Shuffle Answers." Shuffle answers to this and all later questions (default off)
// "Don't Shuffle Answers."  Undoes a "Shuffle Answers".
// "Shuffle Questions."  Shuffle the list of questions (default off)
// "Don't Shuffle Questions."  Undoes a "Shuffle Questions."  
// "Shuffle These Answers."  Shuffles answers to current question only; does not affect later questions
// "Don't Shuffle These Answers."  Cancels any shuffling to current question only; does not affect later questions
// 
// Lines beginning with // will be ignored by the interpreter.
// 
// Please send any comments or suggestions to tao@math.ucla.edu


import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
import java.io.*;
import java.net.*;

public class MultipleChoice extends JApplet 
 {
// GUI components
  JPanel  upper, middle;
  JTextArea outputArea, questionArea;
  JTextArea answerFields[];
  JButton answerButtons[];
  JButton nextButton;
  JComboBox index;
  final int NUM_BUTTONS = 7;
  String buttonStrings[] = {"A", "B", "C", "D", "E", "F", "G"};

// Question file index variables
  Vector fileDescriptions;     // These are vectors of strings.  I should be smarter about this and have a unified vector
  Vector fileNames;            // but I'm too lazy to make another class.

// Multiple choice test variables
  int currentQuestionNum;
  int numQuestions;
  int score;
  int maxScore;
  boolean questionAnswered;
  ShuffleVector questionList;

// Parser variables
  Question q;
  Answer a;
  int value;
  boolean shuffleAnswers;
  int mode;
  final int GLOBAL_MODE = 0;
  final int QUESTION_MODE = 1;
  final int ANSWER_MODE = 2;
  

////////////////////// Constructors ///////////////////////
  public void init() 
   {
    int i;
    
   
    getContentPane().setLayout(new BorderLayout());
    getContentPane().add(upper = new JPanel(), BorderLayout.NORTH);
    getContentPane().add(middle =new JPanel(), BorderLayout.CENTER);
    upper.setLayout(new GridBagLayout());
    middle.setLayout(new GridBagLayout());

// upper third of applet

    getFiles();
    addComponent(upper,new JLabel( "Select category: "), 0 , 0);
    addComponent(upper,index = new JComboBox(fileDescriptions), 0, 1);
    addComponent(upper, nextButton = new JButton("Next Question >>"), 0, 2);
    addComponent(upper, questionArea = new JTextArea(4,50),1,0,3,3);
    questionArea.setLineWrap(true);
    questionArea.setWrapStyleWord(true);
    questionArea.setEditable(false);

// middle third of applet
				
    
    answerButtons = new JButton[NUM_BUTTONS];
    answerFields = new JTextArea[NUM_BUTTONS];
    
    for (i = 0; i < NUM_BUTTONS; i++)
     { 
      addComponent(middle, answerButtons[i] = new JButton(buttonStrings[i]), i, 0);
      addComponent(middle, answerFields[i] = new JTextArea(2,50), i, 1, 2, 1);

      answerFields[i].setLineWrap(true);
      answerFields[i].setWrapStyleWord(true);
      answerFields[i].setEditable(false);
      if (i % 2 == 1) answerFields[i].setBackground(Color.lightGray);
     }


// lower third of applet
  
    getContentPane().add(outputArea = new JTextArea(8,40), BorderLayout.SOUTH);
    outputArea.setLineWrap(true);
    outputArea.setWrapStyleWord(true);

// get data

    getQuestions("");
    displayQuestion();

    
// set Listeners

    for (i = 0; i < NUM_BUTTONS; i++)			// Answer button listeners
    {
     answerButtons[i].addActionListener(new ActionListener()
      {
       public void actionPerformed(ActionEvent e)
        {
         int a = 0;

         for (int j = 0; j < NUM_BUTTONS; j++)
           if (e.getSource() == answerButtons[j])
             a = j;

	 Question currentQuestion = getCurrentQuestion();
	 int c = currentQuestion.getCorrectAnswer();
         Answer ans = currentQuestion.getAnswer(a);

	 if (ans.isEmpty()) return;
	 
         output("Answer " + answerButtons[a].getText() + " is " + ans.getVerdict() + ".");
         if (ans.hasComment())
           output(ans.getComment());
         
	 if (currentQuestion.hasComment() && ans.getValue() == Answer.CORRECT)
           output(currentQuestion.getComment());

         if (questionAnswered) return;
	 questionAnswered = true;	 
	 
//	 if (ans.getValue() != Answer.CORRECT)
//		 output("The correct answer was " + answerButtons[c].getText() + ".");

	 int currentScore = currentQuestion.getScore(ans);
	 score += currentScore;
	 maxScore += currentQuestion.getMaxScore();
	 
	 output("You added " + currentQuestion.getScore(ans) + " to your score, which is now " + score + " (out of " + maxScore + ").");
	}
      });
    }

    nextButton.addActionListener(new ActionListener()		// The next Button listener
     {
      public void actionPerformed(ActionEvent e)
       {
        if (!questionAnswered)
         {
          maxScore += getCurrentQuestion().getMaxScore();
          questionAnswered = true;  // empty answer is an answer; usually will get cleared when question number is advanced
         }

	if (currentQuestionNum >= getNumQuestions() - 1)
	{
		clearOutput();
		output("No more questions.  Please select a new list of questions.");
		output("Your final score was " + score + " (out of " + maxScore + ").");
                if (score == maxScore) output("Congratulations, you had a perfect score!");
		return;
	}
	currentQuestionNum++;	
	questionAnswered = false;
	displayQuestion();
        clearOutput();
       }
     });
		   

    index.addActionListener(new ActionListener()                  // The category selection listener
     {
      public void actionPerformed(ActionEvent e)
       {
	 int j = index.getSelectedIndex();
	 String urlString = (String) fileNames.elementAt(j);
	 if (urlString.length() == 0 && j > 0) return;
	 getQuestions(urlString);	       	       
	 displayQuestion();
       }
     });
			    
   }

  private void addComponent(  JPanel p , Component c, int row, int column, int width, int height)
   {
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.gridx= column;
    gbc.gridy= row;
    gbc.gridheight = height;
    gbc.gridwidth = width;
    p.add( c,gbc);
   }

  private void addComponent(  JPanel p , Component c, int row, int column)
   {
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.gridx= column;
    gbc.gridy= row;
    p.add( c,gbc);
   }


////////////////////// Data entry ///////////////////////

  void getQuestions(String urlString)
   {
    questionList = new ShuffleVector();

    initTest();

    if (urlString.length() == 0) return;
    
    clearOutput();
// initalize parse variables
    q = new Question();
    a = new Answer();
    value = Question.DEFAULT_VALUE;
    shuffleAnswers = false;
    mode = GLOBAL_MODE;
    
    try
    {
	    URL url = new URL(urlString);
	    URLConnection conn = url.openConnection();
	    BufferedReader data = new BufferedReader(new InputStreamReader(conn.getInputStream()));
	    String line;
	    while ((line = data.readLine()) != null)
	        parse(line.trim());
	    data.close();
    }
    catch (MalformedURLException e) {
      output("Unable to create URL: " + urlString);
    }
    catch (IOException e) {
      output("IO Error while loading questions: " + e.getMessage());
    }

   }

void initTest() 
 {
// initialize multiple choice test variables
    currentQuestionNum = -1;   // empty question
    questionAnswered = false;
    score = 0;
    maxScore = 0;
 }

////////////////////// Parser ///////////////////////

  public void parse(String line)   // A simple, interpreted parser for question text data.
   {
    if (line.length() == 0) return;   // ignore whitespace
	 
    if (line.startsWith("Question.")
		    || line.startsWith("Q."))  // A new question!
     {
      q = new Question(content(line), shuffleAnswers, value); 
      questionList.add(q);
      mode = QUESTION_MODE;
      return;
     }
  
    if (line.startsWith("Comment.") || line.startsWith("Remark"))  // A comment!
     {
      switch (mode)
       {
        case GLOBAL_MODE:  // global comment
	  output(content(line));
	  return;
	case QUESTION_MODE: // comment to the current question
	  q.appendComment(content(line));
	  return;
	case ANSWER_MODE: // comment to the current answer
	  a.appendComment(content(line));
	  return;
       }
      return;
     } 

    if (line.startsWith("//"))  // ignore remarks
	    return;
    
    if (line.startsWith("Answer.") 
		    || line.startsWith("Incorrect Answer.")
		    || line.startsWith("A."))  // An incorrect answer!
     {
      a = new Answer(content(line));
      q.addAnswer(a);
      mode = ANSWER_MODE;
      return;
     }

    if (line.startsWith("Partially Correct Answer."))  // A partially correct answer!
     {
      a = new Answer(content(line), Answer.PARTIALLY_CORRECT);
      q.addAnswer(a);
      mode = ANSWER_MODE;
      return;
     }

    if (line.startsWith("Correct Answer."))  // A correct answer!
     {
      a = new Answer(content(line), Answer.CORRECT);
      q.addAnswer(a);
      mode = ANSWER_MODE;
      return;
     }

    if (line.startsWith("Shuffle Answers.") || line.startsWith("Do Shuffle Answers."))
     {
      shuffleAnswers = true;
      q.shuffleAnswers();
      return;
     }

    if (line.startsWith("Don't Shuffle Answers."))
     {
      shuffleAnswers = false;
      q.unshuffleAnswers();
      return;
     }

    if (line.startsWith("Shuffle These Answers.") || line.startsWith("Do Shuffle These Answers.")) 
		// this command and the next are transient - they don't persist to the next question.
     {
      q.shuffleAnswers();
      return;
     }

    if (line.startsWith("Don't Shuffle These Answers."))
     {
      q.unshuffleAnswers();
      return;
     }

    if (line.startsWith("Shuffle Questions.") || line.startsWith("Do Shuffle Questions."))
     {
      questionList.shuffle();
      return;
     }

    if (line.startsWith("Don't Shuffle Questions."))
     {
      questionList.unshuffle();
      return;
     }


    if (line.startsWith("Value."))  // Set points value for a question
     { 
      try
       {
	value = Integer.valueOf(content(line)).intValue();
       }
      catch (NumberFormatException e)
       {
	       output("Ignored: bad points value: " + content(line));
       }
      q.setValue(value);
      return;
     }
  
    if (line.startsWith("Correctness."))  // Set correctness value of an answer (out of 10)
     { 
      try
       {
	int type = Integer.valueOf(content(line)).intValue();
	a.setType(type);
       }
      catch (NumberFormatException e)
       {
        output("Ignored: bad correctness value: " + content(line));
       }
      return;
     }

    output("Ignored: " + line);    
   }

String content(String line) // returns the portion of line after .
 {
  int i = line.indexOf('.');
  return line.substring(i+1).trim();
 }
  
////////////////////// Queries ///////////////////////

  Question getCurrentQuestion()
  {
	  if (currentQuestionNum >= questionList.size() || currentQuestionNum < 0)
	    return new Question();
	  else
	    return (Question) questionList.getShuffled(currentQuestionNum);
  }

  int getNumQuestions()
  {
	  return questionList.size();
  }

  void getFiles()
  {
	  fileDescriptions = new Vector();
	  fileNames = new Vector();

	  fileDescriptions.add("(None)");
	  fileNames.add("");
	  
          try
           {
	    URL url = new URL(getParameter("Index"));
	    URLConnection conn = url.openConnection();
	    BufferedReader data = new BufferedReader(new InputStreamReader(conn.getInputStream()));
	    String line;
	    while ((line = data.readLine()) != null)
	     {
	      if (line.indexOf('|') == -1)
	       {
		       fileDescriptions.add(line.trim());
		       fileNames.add("");
	       }
	      else
	       {
		       int i = line.indexOf('|');
		       fileDescriptions.add(line.substring(0,i).trim());
		       fileNames.add(line.substring(i+1).trim());
	       }	      
             }
	    data.close();
           }
          catch (MalformedURLException e) {
          output("Unable to create URL: " + getParameter("Index"));
           }
     catch (IOException e) {
      output("IO Error while reading index: " + e.getMessage());
    }
  }
	  
////////////////////// Methods ///////////////////////

  void displayQuestion()
   {
    Question q = getCurrentQuestion();
    questionArea.setText("Question " + (currentQuestionNum+1) + " (of " + getNumQuestions() + "). [" + q.getMaxScore() + " points] " + q.getText());
    for (int i = 0; i < NUM_BUTTONS; i++)
      answerFields[i].setText(q.getAnswerText(i));
   }
  
  void clearOutput()
   {
    outputArea.setText("");
   }
  
  void output(String s)
   {
    outputArea.append(s + "\n");
   }
  
 }