
// Base64 encode / decode
// http://www.webtoolkit.info/

const BASE_64_CHR = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';

/*jslint bitwise: true*/
const Base64 = {

	// public method for urlsafe encoding
	urlsafe_encode: (input) => Base64.encode(input)
		.replace(/[+]/g, '-').replace(/[\/]/g, '_').replace(/[=]/g, '.'),

	// public method for encoding
	encode: (input) => {
		
		let
			output = '',
			chr1, chr2, chr3, enc1, enc2, enc3, enc4,
			i = 0
		;

		input = Base64._utf8_encode(input);

		while (i < input.length)
		{
			chr1 = input.charCodeAt(i++);
			chr2 = input.charCodeAt(i++);
			chr3 = input.charCodeAt(i++);

			enc1 = chr1 >> 2;
			enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
			enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
			enc4 = chr3 & 63;

			if (isNaN(chr2))
			{
				enc3 = enc4 = 64;
			}
			else if (isNaN(chr3))
			{
				enc4 = 64;
			}

			output = output +
				BASE_64_CHR.charAt(enc1) + BASE_64_CHR.charAt(enc2) +
				BASE_64_CHR.charAt(enc3) + BASE_64_CHR.charAt(enc4);
		}

		return output;
	},

	// public method for decoding
	decode: (input) => {

		let
			output = '',
			chr1, chr2, chr3, enc1, enc2, enc3, enc4,
			i = 0
		;

		input = input.replace(/[^A-Za-z0-9\+\/\=]/g, '');

		while (i < input.length)
		{
			enc1 = BASE_64_CHR.indexOf(input.charAt(i++));
			enc2 = BASE_64_CHR.indexOf(input.charAt(i++));
			enc3 = BASE_64_CHR.indexOf(input.charAt(i++));
			enc4 = BASE_64_CHR.indexOf(input.charAt(i++));

			chr1 = (enc1 << 2) | (enc2 >> 4);
			chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
			chr3 = ((enc3 & 3) << 6) | enc4;

			output = output + String.fromCharCode(chr1);

			if (enc3 !== 64)
			{
				output = output + String.fromCharCode(chr2);
			}

			if (enc4 !== 64)
			{
				output = output + String.fromCharCode(chr3);
			}
		}

		return Base64._utf8_decode(output);
	},

	// private method for UTF-8 encoding
	_utf8_encode: (string) => {

		string = string.replace(/\r\n/g, "\n");

		let
			utftext = '',
			n = 0,
			l = string.length,
			c = 0
		;

		for (; n < l; n++) {

			c = string.charCodeAt(n);

			if (c < 128)
			{
				utftext += String.fromCharCode(c);
			}
			else if ((c > 127) && (c < 2048))
			{
				utftext += String.fromCharCode((c >> 6) | 192);
				utftext += String.fromCharCode((c & 63) | 128);
			}
			else
			{
				utftext += String.fromCharCode((c >> 12) | 224);
				utftext += String.fromCharCode(((c >> 6) & 63) | 128);
				utftext += String.fromCharCode((c & 63) | 128);
			}
		}

		return utftext;
	},

	// private method for UTF-8 decoding
	_utf8_decode: (utftext) => {

		let
			string = '',
			i = 0,
			c = 0,
			c2 = 0,
			c3 = 0
		;

		while ( i < utftext.length )
		{
			c = utftext.charCodeAt(i);

			if (c < 128)
			{
				string += String.fromCharCode(c);
				i++;
			}
			else if((c > 191) && (c < 224))
			{
				c2 = utftext.charCodeAt(i+1);
				string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
				i += 2;
			}
			else
			{
				c2 = utftext.charCodeAt(i+1);
				c3 = utftext.charCodeAt(i+2);
				string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
				i += 3;
			}
		}

		return string;
	}
};

module.exports = Base64;
/*jslint bitwise: false*/
