//
// ROTn.js -- ROT13 and ROT14
//
// JavaScript-code   implementing   ROT13  and   ROT47.    Useful  to   obscure
// email-adresses and telephone numbers from inquisitorial site crawlers.
//
// Usage:
//   <script type="text/javascript">
//     ROT13('<n uers="znvygb:vasb@ivfhnypb.qr">vasb@ivfhnypb.qr</n>');
//   </script>
//
// Resources:
//     http://de.wikipedia.org/wiki/ROT13
//     http://www.drweb.de/magazin/codieren-und-verschlusseln-mit-javascript/
//
////////////////////////////////////////////////
// (C) 2010 Andreas  Spindler. Permission to use, copy,  modify, and distribute
// this software and  its documentation for any purpose with  or without fee is
// hereby  granted.   Redistributions of  source  code  must  retain the  above
// copyright notice and the following disclaimer.
//
// THE SOFTWARE  IS PROVIDED  "AS IS" AND  THE AUTHOR DISCLAIMS  ALL WARRANTIES
// WITH  REGARD   TO  THIS  SOFTWARE   INCLUDING  ALL  IMPLIED   WARRANTIES  OF
// MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// SPECIAL,  DIRECT,   INDIRECT,  OR  CONSEQUENTIAL  DAMAGES   OR  ANY  DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF  CONTRACT, NEGLIGENCE  OR OTHER  TORTIOUS ACTION,  ARISING OUT  OF  OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
// 
// $Writestamp: 2010-06-09 13:07:07$
// $Maintained at: www.visualco.de$

function ROTn(text, map) {
  // Generic ROT-n algorithm for keycodes in MAP.
  var R = new String()
  var i, j, c, len = map.length
  for(i = 0; i < text.length; i++) {
    c = text.charAt(i)
    j = map.indexOf(c)
    if (j >= 0) {
      c = map.charAt((j + len / 2) % len)
    }
    R = R + c
  }
  return R;
}

function ROT13(text) {
  // Hides all uppercase and lowercase letters.
  var R = new String()
  R = ROTn(text, "ABCDEFGHIJKLMNOPQRSTUVWXYZ")
  R = ROTn(R,    "abcdefghijklmnopqrstuvwxyz")
  return R;
}

function ROT47(text) {
  // Hides all ASCII-characters from 33 ("!") to 126 ("~").  Hence can be used
  // to obfuscate virtually any text, including URLs and emails.
  var R = new String()
  R = ROTn(text,
  "!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~")
  return R;
}

function t0f0g(text, n) {
  // Obfuscate text using ROTn.  Simply some less verbose function
  // name. Etomology: "to fog".
  if (n == 13) {
     return ROT13(text)
  } else if (n == 47) {
     return ROT47(text)
  } else {
     return "???"
  }
}

// end of file ROTn.js