/**
 *  Implements a test for simple unsigned binary numbers
 *  It uses BinaryException and BinaryTextField Classes
 * 
 * @author Mr J
 * @version 20040221
 */
import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
 
public class BinaryQuiz extends Applet implements ActionListener 
{
  // Using our new TextField objects
  BinaryTextField  numberB = new BinaryTextField(20);
  IntegerTextField numberD = new IntegerTextField(20);
  // awt interface objects
  Label messages = new Label("Messages appear here.......................");
  Button answer   = new Button("Check Answer");
  Button again   = new Button("Try again");
  // check if they have answered the question yet 
  boolean answered = false; 
  /**
   * Add objects to Applet, initialise Choice
  */
  public void init() 
  {
    // set up panels for the TextFields and Buttons
    Panel fieldPanel = new Panel();
    fieldPanel.setLayout(new GridLayout( 2, 1 ) );
    Panel buttonPanel = new Panel();
    buttonPanel.setLayout(new GridLayout( 1, 2 ) );
    // add to panels
	fieldPanel.add(numberB);
	fieldPanel.add(numberD);
	buttonPanel.add(answer);
	buttonPanel.add(again);
	// action Listeners for the buttons
	answer.addActionListener(this);
	again.addActionListener(this);
	// set up the interface
	add(fieldPanel);
	add(buttonPanel);
	add(messages);
	// start off with a new question
	generateQuestion();
  }
  /**
   * When the press button is pressed the answer is checked
   * When the again button is pressed a new number is generated
   * 
   * @param e the event that generated the call to this method
   */
   public void actionPerformed(java.awt.event.ActionEvent e)  
  {
    if (e.getSource() == answer)
    {
      if (processAnswer())
      {
        messages.setText("Correct, well done!");
        answered = true;
      }
    }
    else
    {
      if (answered)
      {
        generateQuestion();
        answered = false;
      }
      else
      {
        messages.setText("But you haven't answered this one yet!");
      }
    }
  }
  /**
   * Process the answer
   * 
   * @return true if the question was answered correctly
   */ 
  private boolean processAnswer()
  {      
    try
    {
      // numberB holds the answer, check it, an exception will be thrown
      // if the answer is not valid binary       
      if (numberD.getInteger() == numberB.convert())
      {
          return true;
      }
      else
      {
          messages.setText("Sorry, please try again");
      }
    }
    catch(BinaryTextFieldException btfe)
    {
      messages.setText(btfe.getMessage());
    }
    return false;
  }
  /**
   * Generate a decimal or binary value, depending on direction
   * disable the TextField holding the question
   */ 
  private void generateQuestion()
  {
    // decinmal to Binary conversion
    // Generate decimal number
    numberD.setText(generateDecimal());
    numberD.setEditable(false);
  }
  /**
  * This method generates a binary byte - useful if you want to reverse the quiz (hint, hint)
  * It returns more 1's than zeros on average
  *
  * @return java.lang.String
  */
  private String generateBinary()
  {
	String s = "";
	int r, p;
	
	for (p = 0; p < 8; p++)
	{
	  r = (int) (Math.random() * 500);	
	  if( r >= 300)
	  {
		s += "0";
	  }
	  else
	  {
	    s += "1";
	  }
	}
	return s;
  }
  /**
   * This method generates an int in the range 0 to 255
   *
   * @return a representation of the integer
   */
  public String generateDecimal()
  {
	  return ("" + (int) (Math.random() * 256));
  }
}