export function encode(input: string) {
  let output = '';
  let chr1, chr2, chr3, enc1, enc2, enc3, enc4;
  let i = 0;

  const _keyStr = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';

  input = _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 + _keyStr.charAt(enc1) + _keyStr.charAt(enc2) + _keyStr.charAt(enc3) + _keyStr.charAt(enc4);
  }

  return output;
}

function _utf8_encode(value: string) {
  value = value.replace(/\r\n/g, '\n');
  let utftext = '';

  for (let n = 0; n < value.length; n++) {
    let c = value.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;
}
