/* Copyright (c) 2000 by Robert Graham (RobertGraham.com) */
/* Adopted by FPC */

/*
This code contains standard Base64 encode/decode routines.
*/

/**
 * Encodes a string according to "Base64 encoding" rules 
 */
function base64Encode(str) {
	var result = "";
	var i = 0;
	var sextet = 0;
	var leftovers = 0;
	var octet = 0;

	for (i=0; i < str.length; i++) {
		octet = str.charCodeAt(i);
		switch( i % 3 )
		{
			case 0:
			{
				sextet = ( octet & 0xFC ) >> 2 ;
				leftovers = octet & 0x03 ;

				// sextet contains first character in quadruple
				break;
			}

			case 1:
			{
				sextet = ( leftovers << 4 ) | ( ( octet & 0xF0 ) >> 4 );
				leftovers = octet & 0x0F ;

				// sextet contains 2nd character in quadruple
				break;
			}

			case 2:
			{
				sextet = ( leftovers << 2 ) | ( ( octet & 0xC0 ) >> 6 ) ;
				leftovers = ( octet & 0x3F ) ;

				// sextet contains third character in quadruple
				// leftovers contains fourth character in quadruple
				break;
			}
		}

		result = result + base64ToAscii(sextet);

		// don't forget about the fourth character if it is there
		if( (i % 3) == 2 )
		{
			result = result + base64ToAscii(leftovers);
		} 

	}

	// figure out what to do with leftovers and padding
	switch( str.length % 3 )
	{
		case 0:
		{
			// an even multiple of 3, nothing left to do
			break ;
		}
		case 1:
		{
			// one 6-bit chars plus 2 leftover bits
			leftovers =  leftovers << 4 ;
			result = result + base64ToAscii(leftovers);
			result = result + "==";
			break ;
		}
		case 2:
		{
			// two 6-bit chars plus 4 leftover bits
			leftovers = leftovers << 2 ;
			result = result + base64ToAscii(leftovers);
			result = result + "=";
			break ;
		}
	}

	return( result );
}


/**
 * Decodes a string that has been previously encoded according to the
 * base64Encode() function.
 */
function base64Decode(str) {
	var result = "";
	var i = 0;
	var x;
	var shiftreg = 0;
	var count = -1;
	var is_binary = false;
	
	for (i=0; i < str.length; i++) {
		c = str.charAt(i);
		if ('A' <= c && c <= 'Z')
			x = str.charCodeAt(i) - 65;
		else if ('a' <= c && c <= 'z')
			x = str.charCodeAt(i) - 97 + 26;
		else if ('0' <= c && c <= '9')
			x = str.charCodeAt(i) - 48 + 52;
		else if (c == '+')
			x = 62;
		else if (c == '/')
			x = 63;
		else
			continue;

		count++;

		switch (count % 4)
		{
		case 0:
			shiftreg = x;
			continue;
		case 1:
			v = (shiftreg<<2) | (x >> 4);
			shiftreg = x & 0x0F;
			break;
		case 2:
			v = (shiftreg<<4) | (x >> 2);
			shiftreg = x & 0x03;
			break;
		case 3:
			v = (shiftreg<<6) | (x >> 0);
			shiftreg = x & 0x00;
			break;
		}

		if (!is_binary && (v < 32 || v > 126) && (v != 0x0d) && (v != 0x0a)) 
		{
			result = result + "<";
			result = result + "0123456789ABCDEF".charAt((v/16)&0x0F);
			result = result + "0123456789ABCDEF".charAt((v/1)&0x0F);
			result = result + ">";
		}
		else
			result = result + String.fromCharCode(v);

	}
	return result.toString();
}

/**
*/
function base64ToAscii(c)
{
	var theChar = 0;
	
	if (0 <= c && c <= 25)
	{
		theChar = String.fromCharCode(c + 65);
	}
	else if (26 <= c && c <= 51)
	{
		theChar = String.fromCharCode(c - 26 + 97);
	}
	else if (52 <= c && c <= 61)
	{
		theChar = String.fromCharCode(c - 52 + 48);
	}
	else if (c == 62)
	{
		theChar = '+';
	}
	else if( c == 63 )
	{
		theChar = '/';
	}
	else
	{
		theChar = String.fromCharCode(0xFF);
	}

	return theChar;
}