// @ts-nocheck
// ref https://gist.github.com/aleiphoenix/5472119
const keyStr = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';

/**
 * encode string to base64
 *
 * @param input
 */
const encode = function(input = ''): string {
  input = input;
  let output = '';
  let chr1, chr2, chr3 = '';
  let enc1, enc2, enc3, enc4 = '';
  let i = 0;

  do {
    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);
    chr1 = chr2 = chr3 = '';
    enc1 = enc2 = enc3 = enc4 = '';
  } while (i < input.length);

  return output;
};

/**
 * decode base64 to string
 *
 * @param input base64 string
 */
const decode = function(input: string): string {
  let output = '';
  let chr1, chr2, chr3 = '';
  let enc1, enc2, enc3, enc4 = '';
  let i = 0;

  // remove all characters that are not A-Z, a-z, 0-9, +, /, or =
  const base64test = /[^A-Za-z0-9\+\/\=]/g;
  if (base64test.exec(input)) {
    alert('There were invalid base64 characters in the input text.\n' +
      "Valid base64 characters are A-Z, a-z, 0-9, '+', '/',and '='\n" +
      'Expect errors in decoding.');
  }
  input = input.replace(/[^A-Za-z0-9\+\/\=]/g, '');

  do {
    enc1 = keyStr.indexOf(input.charAt(i++));
    enc2 = keyStr.indexOf(input.charAt(i++));
    enc3 = keyStr.indexOf(input.charAt(i++));
    enc4 = keyStr.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);
    }

    chr1 = chr2 = chr3 = '';
    enc1 = enc2 = enc3 = enc4 = '';

  } while (i < input.length);

  return output;
};


export { encode, decode };