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

/**
    Program:  NaivePrimalityTester
    Purpose:  most naive primality tester
    @author:  Paul Garrett, garrett@math.umn.edu
	 copyright Paul Garrett, GNU Public License, 1997
    @version: Sat Oct 18 18:06:12 CDT 1997
*/

public class NaivePrimalityTester extends Applet {

  int height, width;
  Color background_color, foreground_color;

  TextField firstTF; // to enter the number
  TextArea TA; // to display the computation
  Button computeB; // also to compute...

  long theX; // the number whose primality is being tested
  boolean queryOK; // boolean which tells whether data is ok
  // to try to execute algorithm upon

  String ErrorMessage;

  /*********************/

  public void init() {

    try {
      background_color = 
	new Color(Integer.parseInt(getParameter("background_color"), 16));
      foreground_color = 
	new Color(Integer.parseInt(getParameter("foreground_color"), 16));
      height = Integer.parseInt(getParameter("height"));
      width = Integer.parseInt(getParameter("width"));
    }
    catch (Exception e) {
      background_color = new Color(0xbaaaaa);
      foreground_color = new Color(0x503030);
      height = 320;
      width = 550;
    }
    setBackground(background_color);
    setForeground(foreground_color);

    setFont(new Font("TimesRoman", Font.PLAIN, 14));

    ErrorMessage = new String("Inputs are not integers, or");
    ErrorMessage += " are too large for the implementation";

    theX = 1234432112347L;

    add(new Label("Enter the integer "));
    firstTF = new TextField(""+theX, 24);
    add(firstTF);

    computeB = new Button("compute");
    add(computeB);

    TA = new TextArea(2,40);
    add(TA);

    queryOK = true; // not OK yet to try to compute
    compute(theX);
  }

  final synchronized void compute(long x) {
    boolean queryPrimeSoFar = true;
    TA.setText("                                                  \n");
    if (x % 2 == 0) {
      TA.setText(" 2 divides "+x);
      queryPrimeSoFar = false;
    }
    int i = 3;
    while (i<=Math.sqrt(Math.abs(x)) && queryPrimeSoFar) {
      if (x % i == 0) {
	TA.setText(" "+i+" divides "+x);
	queryPrimeSoFar = false;
      }
      i += 2; // in any case
    }
    if (queryPrimeSoFar && x > 1) {
      TA.setText(" "+x+" is prime ");
    }
  }

  public final synchronized boolean action(Event e, Object arg) {
    if (e.target instanceof TextField || e.target == computeB) {
      String first = Clean.clean(firstTF.getText());
      if (first.length() <= 18) {
			 theX = Long.parseLong(first);
			 queryOK = true;
      }
      else {
			 queryOK = false;
      }
      if (queryOK) {
			 compute(theX);
      }
      else {
			 TA.setText(ErrorMessage);
      }
      return true;
    }
    else {
      return false; // old AWT event model...
    }
  } 

} // the end

/*******************************
 *
 * The End
 *
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