/*
 * TextWidget - Visual Java Cipher text deciphering  widget
 *
 * Copyright (c) 1996 Chuck McManis, All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies.
 *
 * CHUCK MCMANIS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE
 * SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING
 * BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. CHUCK MCMANIS
 * SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT
 * OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */

import java.applet.Applet;
import java.awt.*;
import util.comm.*;
import java.util.Vector;
import java.net.URL;
import java.io.DataInputStream;


/**
 * Display a decrypted text area on the screen.
 */
public class TextWidget extends Applet implements Runnable {
    private DataChannel dc;
    private Thread updater;
    private String myChannel;
    private int rows, cols;
    TextArea txtArea;
    Color bgColor;

    int getInteger(String t, int d) {
	String x = getParameter(t);
	if (x == null)
	    return d;
	try {
	    return (Integer.parseInt(x));
	} catch (NumberFormatException e) { return d; }
    }

    String id;

    /**
     * return one of the "primary" colors.
     */
    Color getPrimaryColor(String xcolor) {
	if (xcolor.equalsIgnoreCase("red")) {
	    return Color.red;
	} else if (xcolor.equalsIgnoreCase("green")) {
	    return Color.green;
	} else if (xcolor.equalsIgnoreCase("yellow")) {
	    return Color.yellow;
	} else if (xcolor.equalsIgnoreCase("blue")) {
	    return Color.blue;
	} else if (xcolor.equalsIgnoreCase("cyan")) {
	    return Color.cyan;
	} else if (xcolor.equalsIgnoreCase("gray")) {
	    return Color.gray;
	} else if (xcolor.equalsIgnoreCase("magenta")) {
	    return Color.magenta;
	} else if (xcolor.equalsIgnoreCase("orange")) {
	    return Color.orange;
	} else if (xcolor.equalsIgnoreCase("pink")) {
	    return Color.pink;
	}
	return null;
    }


   /**
     * Return a Color value from the parameter list. Colors are
     * specified using HEX notation as in NetScape. If there is any
     * error, return the defaultColor instead.
     */
    public Color getColor(String name, Color defaultColor) {
    	String x = getParameter(name);
	if (x != null) {
	   if (x.startsWith("0x")) {
		int z;
		try {
		    z = Integer.parseInt(x.substring(2), 16);
		    return( new Color((z >>> 16) & 0xff,
				          (z >>> 8) & 0xff,
				          (z & 0xff)));
		} catch (NumberFormatException e) { return defaultColor; }
            } else if (x.startsWith("#")) {
                int z;
	        try {
	            z = Integer.parseInt(x.substring(1), 16);
	            return( new Color((z >>> 16) & 0xff, (z >>> 8) & 0xff,
			                             (z & 0xff)));
	        } catch (NumberFormatException e) { return defaultColor; }
            } else if (x.substring(0, 4).equalsIgnoreCase("dark")) {
            	Color y = getPrimaryColor(x.substring(4));
            	if (y != null)
            	    return y.darker();
            	return defaultColor;
            } else if (x.substring(0, 5).equalsIgnoreCase("light")) {
            	Color y = getPrimaryColor(x.substring(5));
            	if (y != null) {
            		return y.brighter();
            	}
            } else {
            	Color y = getPrimaryColor(x);
            	if (y != null)
            	    return y;
            	return defaultColor;
            }
	}
	return defaultColor;
    }

    /**
     * Parameters :
     *	 	 id = the identifier for our cipher text.
     *	datachannel = the channel that will get the password.
     *	       rows = number of rows in the text area;
     *         cols = number of columns.
     */
    public void init() {
	String x;
	int	w = size().width;
	int	h = size().height;

 	id = getParameter("id");
	x = getParameter("datachannel");
	if (x == null)
	    myChannel = "test";
	else
	    myChannel = x;
	rows = getInteger("rows", h / 20);
 	cols = getInteger("cols", w / 8);
 	bgColor = getColor("bgcolor", Color.lightGray);
	txtArea = new TextArea(rows, cols);
	add(txtArea);
    }

    public void paint(Graphics g) {
    	g.setColor(bgColor);
    	g.fillRect(0, 0, size().width, size().height);
    }

    public void start() {
	updater = new Thread(this);

	dc = DataChannel.getChannel(myChannel, updater, 8);
	updater.start();
    }

    public void stop() {
	updater = null;
    }

    /**
     * Return a byte from hex digits.
     */
    byte makeByte(char msd, char lsd) {
    	int m, l;

    	m = Character.toUpperCase(msd) - '0';
    	if (m > 9)
    	    m -= 7;

    	l = Character.toUpperCase(lsd) - '0';
    	if (l > 9)
    	    l -= 7;

    	return (byte)((m << 4) + l); // XXX doesn't detect bogus data
    }

    /**
     * Retrieve the cipher text from the .html file. Normally the
     * HTML file would have been generated by a cgi script and the
     * cipher would be triple des or something. However, for our demo
     * We are using a simple XOR cipher to demonstrate the concept without
     * running afoul of the ITAR regulations.
     */
    byte [] getCipherText() {
    	Vector data = new Vector();
    	String s;
    	byte oneLine[];
    	DataInputStream dis;
    	URL myDoc;
    	boolean capture = false;
	int	totalLen = 0;
	byte	result[];

	try {
    	myDoc = getDocumentBase();
    	dis = new DataInputStream(myDoc.openStream());
    	// Normally I'd use one of the CharacterDecoder streams
    	while (true) {
    	    s = dis.readLine();
    	    if (s == null)
    	    	break;

    	    if (capture && (s.compareTo("-->") == 0))
    	        break;
    	    if (! capture) {
    	    	capture = s.compareTo("<!-- CipherText : "+id) == 0;
    	    	continue;
    	    }

    	    int t = s.length() / 2; // optimization
    	    oneLine = new byte[t];
    	    for (int i = 0; i < t; i++) {
    	    	oneLine[i] = makeByte(s.charAt(i*2), s.charAt((i*2)+1));
    	    }
    	    data.addElement(oneLine);
    	    totalLen += t;
    	}
    	if (totalLen == 0)
    	    return null;

    	result = new byte[totalLen];
    	int ndx = 0;
    	for (int i = 0; i < data.size(); i++) {
    	    oneLine = (byte [])(data.elementAt(i));
    	    for (int j = 0; j < oneLine.length; j++) {
    	    	result[ndx++] = oneLine[j];
    	    }
    	}

    	return result;
	} catch (Exception e) { e.printStackTrace(); return null; }
    }

    /**
     * Receives the password when sent, decypts the cipher text,
     * and displays it in its text area component.
     */
    public void run() {
	int count = 0;
	String s;
	byte ciphertext[];
	byte passwd[];
	int keybyte = 0;

	ciphertext = getCipherText();
	while (updater == Thread.currentThread()) {
	    try {
	        s = (String)(dc.getValue());
	    } catch (Exception e) { return; }
	    byte checksum = (byte) -1;
	    keybyte = 0;
	    passwd = new byte[s.length()];
	    s.getBytes(0, s.length(), passwd, 0);
//	    txtArea.appendText("Password : "+s+"\n");
	    StringBuffer q = new StringBuffer();
	    for (int i = 0; i < ciphertext.length - 1; i++) {
	    	char x = (char) (ciphertext[i] ^ passwd[keybyte]);
	    	checksum = (byte)(checksum +  x) ;
	    	keybyte = (keybyte+1) % passwd.length;
	    	q.append(x);
	    }
	    System.out.println("Checksum is "+checksum);
	    byte last = (byte) (ciphertext[ciphertext.length - 1] ^ passwd[keybyte]);
	    System.out.println("Last byte is " + last);
	    checksum = (byte) (checksum + last);
	    System.out.println("Final checksum is : " + checksum);
	    if (checksum == 0) {
	        txtArea.appendText(q.toString());
	        repaint();
	    }
	}
    }
}