/*
 * Material Experience - Encoder/Decoder Module
 * 
 * EYEMG - Interactive Media Group
 * Updated by Mike Crute (mcrute@eyemg.com) on 9/26/07
 * 
 * Encoder/Decoder module for common encoding schemes like URL and 
 * base64. Code from: http://ostermiller.org/calc/encode.html
 */
var END_OF_INPUT = -1;

var base64Chars = new Array(
	'A','B','C','D','E','F','G','H',
	'I','J','K','L','M','N','O','P',
	'Q','R','S','T','U','V','W','X',
	'Y','Z','a','b','c','d','e','f',
	'g','h','i','j','k','l','m','n',
	'o','p','q','r','s','t','u','v',
	'w','x','y','z','0','1','2','3',
	'4','5','6','7','8','9','+','/'
);

var reverseBase64Chars = new Array();
var base64Str;
var base64Count;

for (var i=0; i < base64Chars.length; i++)
{
	reverseBase64Chars[base64Chars[i]] = i;
}

// -------------------------------------------------------------------------- \\

function urlDecode(str)
{
	return unescape(str.replace(new RegExp('\\+','g'),' '));
}

function urlEncode(str)
{
	str = escape(str);
	str = str.replace(new RegExp('\\+','g'),'%2B');
	
	return str.replace(new RegExp('%20','g'),'+');
}

// -------------------------------------------------------------------------- \\

function setBase64Str(str)
{
	base64Str   = str;
	base64Count = 0;
}

function readBase64()
{
	if (!base64Str) 
	{
		return END_OF_INPUT;
	}
	
	if (base64Count >= base64Str.length)
	{
		return END_OF_INPUT;
	}
	
	var c = base64Str.charCodeAt(base64Count) & 0xff;
	
	base64Count++;
	
	return c;
}

function encodeBase64(str)
{
	setBase64Str(str);
	
	var result    = '';
	var inBuffer  = new Array(3);
	var lineCount = 0;
	var done      = false;
    
	while (!done && (inBuffer[0] = readBase64()) != END_OF_INPUT)
	{
		inBuffer[1]  = readBase64();
		inBuffer[2]  = readBase64();
		result      += (base64Chars[ inBuffer[0] >> 2 ]);
		
		if (inBuffer[1] != END_OF_INPUT)
		{
			result += (base64Chars [(( inBuffer[0] << 4 ) & 0x30) | (inBuffer[1] >> 4) ]);
	
			if (inBuffer[2] != END_OF_INPUT)
			{
				result += (base64Chars [((inBuffer[1] << 2) & 0x3c) | (inBuffer[2] >> 6) ]);
				result += (base64Chars [inBuffer[2] & 0x3F]);
			}
			else 
			{
				result += (base64Chars [((inBuffer[1] << 2) & 0x3c)]);
				result += ('=');
				done    = true;
			}
		}
		else 
		{
			result += (base64Chars [(( inBuffer[0] << 4 ) & 0x30)]);
			result += ('=');
			result += ('=');
			done    = true;
		}
		
		lineCount += 4;
		
		if (lineCount >= 76)
		{
			result   += ('\n');
			lineCount = 0;
		}
	}

	return result;
}

function readReverseBase64()
{
	if (!base64Str)
	{
		return END_OF_INPUT;
	}
	
	while (true)
	{
		if (base64Count >= base64Str.length)
		{
			return END_OF_INPUT;
		}
		
		var nextCharacter = base64Str.charAt(base64Count);
		base64Count++;
		
		if (reverseBase64Chars[nextCharacter])
		{
			return reverseBase64Chars[nextCharacter];
		}
		
		if (nextCharacter == 'A') 
		{
			return 0;
		}
	}
	
	return END_OF_INPUT;
}

function ntos(n)
{
	n = n.toString(16);
	
	if (n.length == 1) 
	{
		n = "0" + n;
	}
	
	n = "%" + n;
	
	return unescape(n);
}

function decodeBase64(str)
{
	setBase64Str(str);
	
	var result   = "";
	var inBuffer = new Array(4);
	var done     = false;

	while (!done && (inBuffer[0] = readReverseBase64()) != END_OF_INPUT
		&& (inBuffer[1] = readReverseBase64()) != END_OF_INPUT)
        {
		inBuffer[2]  = readReverseBase64();
		inBuffer[3]  = readReverseBase64();
		result      += ntos((((inBuffer[0] << 2) & 0xff)| inBuffer[1] >> 4));
		
		if (inBuffer[2] != END_OF_INPUT)
		{
			result +=  ntos((((inBuffer[1] << 4) & 0xff)| inBuffer[2] >> 2));

			if (inBuffer[3] != END_OF_INPUT)
			{
				result +=  ntos((((inBuffer[2] << 6)  & 0xff) | inBuffer[3]));
			}
			else 
			{
				done = true;
			}
		} 
		else 
		{
			done = true;
		}
	}
	
	return result;
}