/**
 * @class String extensions
 */
Object.extend(String.prototype, 
{
	/**
	 * @param {String} "left" to pad the string on the left, "right" to pad right.
	 * @param {Number} minimum string length.
	 * @param {String} character(s) to pad 
	 * @return {String} padded character(s) on the left or right to satisfy minimum string length
	 */

	pad : function(side, len, chr) {
		if (!chr) chr = ' ';
		var s = this;
		var left = side.toLowerCase()=='left';
		while (s.length<len) s = left? chr + s : s + chr;
		return s;
	},

	/**
	 * @param {Number} minimum string length.
	 * @param {String} character(s) to pad 
	 * @return {String} padded character(s) on the left to satisfy minimum string length
	 */
	padLeft : function(len, chr) {
		return this.pad('left',len,chr);
	},

	/**
	 * @param {Number} minimum string length.
	 * @param {String} character(s) to pad 
	 * @return {String} padded character(s) on the right to satisfy minimum string length
	 */
	padRight : function(len, chr) {
		return this.pad('right',len,chr);
	},

	/**
	 * @param {Number} minimum string length.
	 * @return {String} append zeros to the left to satisfy minimum string length.
	 */
	zerofill : function(len) { 
		return this.padLeft(len,'0');
	},

	/**
	 * @return {String} removed white spaces from both ends.
	 */
	trim : function() { 
		return this.replace(/^\s+|\s+$/g,'');
	},

	/**
	 * @return {String} removed white spaces from the left end.
	 */
	trimLeft : function() { 
		return this.replace(/^\s+/,''); 
	},

	/**
	 * @return {String} removed white spaces from the right end.
	 */
	trimRight : function() { 
		return this.replace(/\s+$/,'');
	},

	/**
	 * Convert period separated function names into a function reference.
	 * e.g. "Prado.AJAX.Callback.Action.setValue".toFunction() will return
	 * the actual function Prado.AJAX.Callback.Action.setValue()
	 * @return {Function} the corresponding function represented by the string.
	 */
	toFunction : function()
	{
		var commands = this.split(/\./);
		var command = window;
		commands.each(function(action)
		{ 
			if(command[new String(action)]) 
				command=command[new String(action)]; 
		});
		if(typeof(command) == "function")
			return command;
		else
		{
			if(typeof Logger != "undefined")
				Logger.error("Missing function", this);
				
			throw new Error	("Missing function '"+this+"'");
		}
	},

	/** 
	 * Convert a string into integer, returns null if not integer.
	 * @return {Number} null if string does not represent an integer.
	 */
	toInteger : function()
	{
		var exp = /^\s*[-\+]?\d+\s*$/;
		if (this.match(exp) == null)
			return null;
		var num = parseInt(this, 10);
		return (isNaN(num) ? null : num);
	},

	/** 
	 * Convert a string into a double/float value. <b>Internationalization 
	 * is not supported</b>
	 * @param {String} the decimal character
	 * @return {Double} null if string does not represent a float value
	 */
	toDouble : function(decimalchar)
	{
		if(this.length <= 0) return null;
		decimalchar = decimalchar || ".";
		var exp = new RegExp("^\\s*([-\\+])?(\\d+)?(\\" + decimalchar + "(\\d+))?\\s*$");
		var m = this.match(exp);
		
		if (m == null)	
			return null;
		m[1] = m[1] || "";
		m[2] = m[2] || "0";
		m[4] = m[4] || "0";
				
		var cleanInput = m[1] + (m[2].length>0 ? m[2] : "0") + "." + m[4];
		var num = parseFloat(cleanInput);
		return (isNaN(num) ? null : num);
	},

	/**
	 * Convert strings that represent a currency value (e.g. a float with grouping 
	 * characters) to float. E.g. "10,000.50" will become "10000.50". The number 
	 * of dicimal digits, grouping and decimal characters can be specified.
	 * <i>The currency input format is <b>very</b> strict, null will be returned if
	 * the pattern does not match</i>.
	 * @param {String} the grouping character, default is ","
	 * @param {Number} number of decimal digits
	 * @param {String} the decimal character, default is "."
	 * @type {Double} the currency value as float.
	 */
	toCurrency : function(groupchar, digits, decimalchar)
	{
		groupchar = groupchar || ",";
		decimalchar = decimalchar || ".";
		digits = typeof(digits) == "undefined" ? 2 : digits;

		var exp = new RegExp("^\\s*([-\\+])?(((\\d+)\\" + groupchar + ")*)(\\d+)"
			+ ((digits > 0) ? "(\\" + decimalchar + "(\\d{1," + digits + "}))?" : "")
			+ "\\s*$");
		var m = this.match(exp);
		if (m == null)
			return null;
		var intermed = m[2] + m[5] ;
		var cleanInput = m[1] + intermed.replace(
				new RegExp("(\\" + groupchar + ")", "g"), "") 
								+ ((digits > 0) ? "." + m[7] : "");
		var num = parseFloat(cleanInput);
		return (isNaN(num) ? null : num);
	},

	/**
	 * Converts the string to a date by finding values that matches the 
	 * date format pattern.
	 * @param string date format pattern, e.g. MM-dd-yyyy
	 * @return {Date} the date extracted from the string
	 */
	toDate : function(format)
	{
		return Date.SimpleParse(this, format);
	}
});