// ====================================================================
//       URLEncode and URLDecode functions
//
// Copyright Albion Research Ltd. 2002
// http://www.albionresearch.com/
//
// You may copy these functions providing that 
// (a) you leave this copyright notice intact, and 
// (b) if you use these functions on a publicly accessible
//     web site you include a credit somewhere on the web site 
//     with a link back to http://www.albionresarch.com/
//
// If you find or fix any bugs, please let us know at albionresearch.com
//
// SpecialThanks to Neelesh Thakur for being the first to
// report a bug in URLDecode() - now fixed 2003-02-19.
// ====================================================================
function URLEncode(plaintext )
{
    // The Javascript escape and unescape functions do not correspond
    // with what browsers actually do...
    var SAFECHARS = "0123456789" +					// Numeric
	"ABCDEFGHIJKLMNOPQRSTUVWXYZ" +	// Alphabetic
	"abcdefghijklmnopqrstuvwxyz" +
	"-_.!~*()";					// RFC2396 Mark characters (JW: removed "'" due to script issues)
    var HEX = "0123456789ABCDEF";

    var encoded = "";
    for (var i = 0; i < plaintext.length; i++ ) {
	var ch = plaintext.charAt(i);
	if (ch == " ") {
	    encoded += "+";				// x-www-urlencoded, rather than %20
	} else if (SAFECHARS.indexOf(ch) != -1) {
	    encoded += ch;
	} else {
	    var charCode = ch.charCodeAt(0);
	    if (charCode > 255) {
		alert( "Unicode Character '" 
			+ ch 
			+ "' cannot be encoded using standard URL encoding.\n" +
			"(URL encoding only supports 8-bit characters.)\n" +
			"A space (+) will be substituted." );
		encoded += "+";
	    } else {
		encoded += "%";
		encoded += HEX.charAt((charCode >> 4) & 0xF);
		encoded += HEX.charAt(charCode & 0xF);
	    }
	}
    } // for

    return encoded;
};

function URLDecode(HEXCHARS )
{
    // Replace + with ' '
    // Replace %xx with equivalent character
    // Put [ERROR] in output if %xx is invalid.
    var HEXCHARS = "0123456789ABCDEFabcdef"; 
    var plaintext = "";
    var i = 0;
    while (i < encoded.length) {
	var ch = encoded.charAt(i);
	if (ch == "+") {
	    plaintext += " ";
	    i++;
	} else if (ch == "%") {
	    if (i < (encoded.length-2) 
		    && HEXCHARS.indexOf(encoded.charAt(i+1)) != -1 
		    && HEXCHARS.indexOf(encoded.charAt(i+2)) != -1 ) {
		plaintext += unescape( encoded.substr(i,3) );
		i += 3;
	    } else {
		alert( 'Bad escape combination near ...' + encoded.substr(i) );
		plaintext += "%[ERROR]";
		i++;
	    }
	} else {
	    plaintext += ch;
	    i++;
	}
    } // while
    return plaintext;
};