/*****************************************
 * String encoding/decoding functions
 * 
 * This work is licensed under a Creative Commons Attribution 3.0 Unported License
 * http://creativecommons.org/licenses/by/3.0/
 *
 * Author: Andy Harrison, http://dragonzreef.com/
 * Date: 16 September 2011
 *****************************************/
 
String.prototype.encodeToUrlPart = function(){ return encodeURIComponent(this); };
String.prototype.decodeFromUrlPart = function(){ return decodeURIComponent(this); };
String.prototype.encodeToUrl = function(){ return encodeURI(this); };
String.prototype.decodeFromUrl = function(){ return decodeURI(this); };
 
//HTML-escapes amphersands that do not designate a character reference
String.prototype.encodeIncongruousAmphersands = function()
{
	var str = this.toString();
	if(!str) return "";
 
	//escape amphersands that are obviously not designating character references
	str = str.replace(/&#x([A-F0-9]*(?:[^A-F0-9;]|$))/ig, "&#x$1");
	str = str.replace(/&#(?!x)([0-9]*(?:[^0-9;]|$))/ig, "&#$1");
	str = str.replace(/&(?!#)([a-z0-9]*(?:[^a-z0-9;]|$))/ig, "&$1");
 
	//for substrings formatted as character entity references, make sure entity names are valid
	//see http://www.w3.org/TR/html401/sgml/entities.html
 
	var validEntityNames = ""+
		//markup-significant and internationalization characters
		"quot|amp|lt|gt|OElig|oelig|Scaron|scaron|Yuml|circ|tilde|ensp|emsp|thinsp|zwnj|zwj|lrm|"+
		"rlm|ndash|mdash|lsquo|rsquo|sbquo|ldquo|rdquo|bdquo|dagger|Dagger|permil|lsaquo|rsaquo|euro|"+
		//ISO 8859-1 characters
		"nbsp|iexcl|cent|pound|curren|yen|brvbar|sect|uml|copy|ordf|laquo|not|shy|reg|macr|deg|"+
		"plusmn|sup2|sup3|acute|micro|para|middot|cedil|sup1|ordm|raquo|frac14|frac12|frac34|iquest|"+
		"Agrave|Aacute|Acirc|Atilde|Auml|Aring|AElig|Ccedil|Egrave|Eacute|Ecirc|Euml|Igrave|Iacute|"+
		"Icirc|Iuml|ETH|Ntilde|Ograve|Oacute|Ocirc|Otilde|Ouml|times|Oslash|Ugrave|Uacute|Ucirc|Uuml|"+
		"Yacute|THORN|szlig|agrave|aacute|acirc|atilde|auml|aring|aelig|ccedil|egrave|eacute|ecirc|euml|"+
		"igrave|iacute|icirc|iuml|eth|ntilde|ograve|oacute|ocirc|otilde|ouml|divide|oslash|ugrave|"+
		"uacute|ucirc|uuml|yacute|thorn|yuml|"+
		//symbols, mathematical symbols, and Greek letters
		"fnof|Alpha|Beta|Gamma|Delta|Epsilon|Zeta|Eta|Theta|Iota|Kappa|Lambda|Mu|Nu|Xi|Omicron|Pi|"+
		"Rho|Sigma|Tau|Upsilon|Phi|Chi|Psi|Omega|alpha|beta|gamma|delta|epsilon|zeta|eta|theta|iota|"+
		"kappa|lambda|mu|nu|xi|omicron|pi|rho|sigmaf|sigma|tau|upsilon|phi|chi|psi|omega|thetasym|"+
		"upsih|piv|bull|hellip|prime|Prime|oline|frasl|weierp|image|real|trade|alefsym|larr|uarr|rarr|"+
		"darr|harr|crarr|lArr|uArr|rArr|dArr|hArr|forall|part|exist|empty|nabla|isin|notin|ni|prod|"+
		"sum|minus|lowast|radic|prop|infin|ang|and|or|cap|cup|int|there4|sim|cong|asymp|ne|equiv|"+
		"le|ge|sub|sup|nsub|sube|supe|oplus|otimes|perp|sdot|lceil|rceil|lfloor|rfloor|lang|rang|"+
		"loz|spades|clubs|hearts|diams";
 
	var rxp = new RegExp("&(?!("+validEntityNames+");)([a-zA-Z0-9]+;)", "g");
	str.replace(rxp, "&$1");
 
	return str;
};
String.prototype.encodeToHtml = function(keepValidEntities)
{
	var str = this.toString();
	if(!str) return "";
	str = keepValidEntities ? str.encodeIncongruousAmphersands() : str.replace(/&/g, "&");
	str = str.replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&quot;").replace(/'/g, "&#39;");
	return str;
};
//unescapes all entities in the string, not just the markup-significant characters
String.prototype.decodeFromHtml = function()
{
	var str = this.toString();
	if(!str) return "";
	var tmp = document.createElement("div");
	tmp.innerHTML = str;
	return tmp.firstChild.nodeValue;
};
 
//escapes the string for use as a JavaScript string in embedded or inline code
//See http://code.google.com/p/doctype/wiki/ArticleXSSInJavaScript
String.prototype.encodeToJavaScriptString = function()
{
	var str = this.toString();
	if(!str) return "";
 
	str = str.replace(/\\/g, "\\\\");
 
	//prevent "escape from the quote" attacks by escaping quotes and line feed characters
	str = str.replace(/'/g, "\\u0027").replace(/"/g, "\\u0022");
	str = str.replace(/\u0009/ig, "\\t").replace(/\u000A/ig, "\\n").replace(/\u000D/ig, "\\r").replace(/\u0085/ig, "\\u0085");	//tab, line feed, carriage return, next line
	str = str.replace(/\u2028/ig, "\\u2028").replace(/\u2029/ig, "\\u2029");	//line separator, paragraph separator
 
	//prevent string from closing the tag
	str = str.replace(/</g, "\\u003C").replace(/>/g, "\\u003E");
 
	//these are escaped just in case ("defense-in-depth")
	str = str.replace(/&/g, "\\u0026").replace(/=/g, "\\u003D");
 
	return str;
};