//JulianCodeApplet, copyright 1999 David Faden
//for The Gilbert Post, http://www.geocities.com/Athens/Parthenon/
//If you use this code,
//please link to The Gilbert Post
//and send an e-mail (unencrypted) to gilbertnews@hotmail.com
import java.applet.*;
import java.net.*;
import java.awt.*;

public class JulianCodeApplet extends Applet {
   private static final String ABC="AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz1234567890&#@?,.;:*()[]{}_!$%-+=";
   private static final String ALL_CHAR=ABC+"~^|\\<>/ \'\"\t\r\n";
   private TextArea text;
   private TextField ring;
   Button ben,bde;
   private List ad;
   private URL thegilbertpost=null;
   private String docBase;
   private static final String JULIANHEADER="[Decode with JulianCode";
   private static final String JULIANCLOSER="[Encoded text ends ABOVE this line.]";

   public void init() {
     try {
       thegilbertpost=new URL("http://www.geocities.com/Athens/Parthenon/1911/");
     }
     catch(MalformedURLException e2) {thegilbertpost=null;}
     docBase=getDocumentBase().toString();
     if(docBase==null) docBase="";
     else docBase=docBase.replace(']',' ');
     setBackground(Color.white);
     setLayout(new BorderLayout());
     Panel p=new Panel();
     p.setLayout(new BorderLayout());
     Panel ptop=new Panel();
     ptop.add(new Label("Keyword:"));
     ring=new TextField(10);
     ring.setEchoCharacter('*');
     ptop.add(ring);
     ptop.add(ben=new Button("Encode"));
     ptop.add(bde=new Button("Decode"));
     p.add("North",ptop);
     p.add("Center",text=new TextArea(35,7));
     String premsg=getParameter("init_msg");
     if(premsg!=null && premsg.length()>0) text.setText(premsg);
     ad=new List(1,false);
     ad.addItem("JulianCodeApplet c1999 The Gilbert Post");
     p.add("South",ad);
     add("Center",p);
   }

   public boolean action(Event e,Object arg) {
     if(e.target==ben) {
       //Bad practice to do major work in an AWTThread but...
       encode();
     }
     else if(e.target==bde) decode();
     else if(e.target==ad) {
       getAppletContext().showDocument(thegilbertpost,"_top");
     }
     return true;
   }


   //called when page containing applet is hidden
   //visitor leaving
   //clear the password/textfields
   public void stop() {
     ring.setText("");
     text.setText("");
   }

   private void encode() {
     char[] cring=ring.getText().toCharArray();
     //validate the cring
     if(cring.length<1) return;
     for(int i=0;i<cring.length;i++) {
        if(ABC.indexOf(cring[i])<1) cring[i]=ABC.charAt(i%(ABC.length()-1)+1);
     }
     char[] ctext=toAlphaNumeric(text.getText()).toCharArray();
     int cindex;
     int counter=0;
     for(int j=0;j<ctext.length;j++) {
        cindex=ABC.indexOf(ctext[j]);
        if(cindex!=-1) {
          counter++;
          ctext[j]=ABC.charAt((cindex+ABC.indexOf(cring[counter%cring.length]))%ABC.length());
        }
     }
     text.setText(JULIANHEADER+" at "+docBase+"\nEncoded text starts BELOW this line.]\n\n"+(new String(ctext))+"\n\n"+JULIANCLOSER+
     "\nThe Gilbert Post http://www.geocities.com/Athens/Parthenon/1911\n"+
     "independent h.s. student paper\n");
   }

   private void decode() {
     String s=text.getText();
     //chop the header
     int hindex=s.indexOf(JULIANHEADER);
     if(hindex!=-1) {
       int brktindex=s.indexOf(']',hindex+JULIANHEADER.length());
       if(brktindex!=-1) s=s.substring(brktindex+1,s.length());
     }
     //chop the footer/closing
     int clindex=s.indexOf(JULIANCLOSER);
     if(clindex!=-1) s=s.substring(0, clindex);
     //
     char[] cring=ring.getText().toCharArray();
     //validate the cring
     if(cring.length<1) return;
     for(int i=0;i<cring.length;i++) {
        if(ABC.indexOf(cring[i])<1) cring[i]=ABC.charAt(i%(ABC.length()-1)+1);
     }
     char[] ctext=s.toCharArray();
     int cindex;
     int realindex;
     int counter=0;
     for(int j=0;j<ctext.length;j++) {
        cindex=ABC.indexOf(ctext[j]);
        if(cindex!=-1) {
          counter++;
          realindex=cindex-ABC.indexOf(cring[counter%cring.length]);
          if(realindex<0) realindex+=ABC.length();
          ctext[j]=ABC.charAt(realindex);
        }
     }
     text.setText(fromAlphaNumeric(new String(ctext)));
   }

   //inserted out of place code to insert a LF to make text look nicer
   private String toAlphaNumeric(String s) {
    StringBuffer sb=new StringBuffer();
    char c;
    int counter=0;
    for(int i=0;i<s.length();i++) {
       c=s.charAt(i);
       if(ABC.indexOf(c)!=-1 && ABC.indexOf(c)<(ABC.length()-1)) {
         sb.append(c);
         counter++;
       }
       else if(ALL_CHAR.indexOf(c)==-1) /*sb.append(c)*/;
       else {
         int aindex=ALL_CHAR.indexOf(c);
         sb.append(ABC.charAt(ABC.length()-1));
         counter++;
         aindex-=ABC.length()-1;
         sb.append(ABC.charAt(aindex));
         counter++;
       }
       if(counter>=50) {
         sb.append('\n');
         counter=0;
       }
    }
    return sb.toString();
  }

  //This method will almost certainly go out of the bounds of ALL_CHAR if
  //the input data has been tampered with...If the input data has been messed up,
  //it cannot be decrypted anyway.
  private String fromAlphaNumeric(String s) {
    StringBuffer sb=new StringBuffer();
    char c;
    int i=-1;
    try {
      for(;;) {
         i++;
         if(i==s.length()) break;
         c=s.charAt(i);
         if(ABC.indexOf(c)==-1);
         else {
           if(ABC.indexOf(c)!=(ABC.length()-1)) sb.append(c);
           else {
             if(i<(s.length()-1)) i++;
             else {sb.append(c); break;}
             c=s.charAt(i);
             if(ABC.indexOf(c)==-1) {sb.append(ABC.charAt(ABC.length()-1)); continue;}
             //Assuming we're receiving encoded input;
             //else this will probably go out of bounds...
             else sb.append(ALL_CHAR.charAt(ABC.length()-1+ABC.indexOf(c)));
           }
         }
      }
    }
    catch(Exception e) {System.out.println(e);}
    return sb.toString();
  }

}