const Base64 = {
  // private property
  _keyStr: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=',

  // public method for encoding
  encode: function (input: string) {
    var output = ''
    var chr1, chr2, chr3, enc1, enc2, enc3, enc4
    var 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 +
        Base64._keyStr.charAt(enc1) +
        Base64._keyStr.charAt(enc2) +
        Base64._keyStr.charAt(enc3) +
        Base64._keyStr.charAt(enc4)
    }

    return output
  },

  // public method for decoding
  decode: function (input: string) {
    var output = ''
    var chr1, chr2, chr3
    var enc1, enc2, enc3, enc4
    var i = 0

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

    while (i < input.length) {
      enc1 = Base64._keyStr.indexOf(input.charAt(i++))
      enc2 = Base64._keyStr.indexOf(input.charAt(i++))
      enc3 = Base64._keyStr.indexOf(input.charAt(i++))
      enc4 = Base64._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)
      }
    }

    output = Base64._utf8_decode(output)

    return output
  },

  // private method for UTF-8 encoding
  _utf8_encode: function (string: string) {
    string = string.replace(/\r\n/g, '\n')
    var utftext = ''

    for (var n = 0; n < string.length; n++) {
      var 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: function (utftext: string) {
    var string = ''
    var i = 0
    var c = 0,
      c1 = 0,
      c2 = 0

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

      if (c < 128) {
        string += String.fromCharCode(c)
        i++
      } else if (c > 191 && c < 224) {
        c1 = utftext.charCodeAt(i + 1)
        string += String.fromCharCode(((c & 31) << 6) | (c1 & 63))
        i += 2
      } else {
        c1 = utftext.charCodeAt(i + 1)
        c2 = utftext.charCodeAt(i + 2)
        string += String.fromCharCode(((c & 15) << 12) | ((c1 & 63) << 6) | (c2 & 63))
        i += 3
      }
    }
    return string
  },
}
export default Base64