var XORCipher = {
  encode: function (key, data, seed) {
    data = xor_encrypt(key, data, seed);
    return b64_encode(data);
  },
  decode: function (key, data) {
    data = b64_decode(data);
    return xor_decrypt(key, data);
  },
  seed: function (n) {
    return randString(n);
  },
};

function stringToUtf8ByteArray(str) {
  var out = [],
    p = 0;
  for (var i = 0; i < str.length; i++) {
    var c = str.charCodeAt(i);
    if (c < 128) {
      out[p++] = c;
    } else if (c < 2048) {
      out[p++] = (c >> 6) | 192;
      out[p++] = (c & 63) | 128;
    } else if (
      (c & 0xfc00) == 0xd800 &&
      i + 1 < str.length &&
      (str.charCodeAt(i + 1) & 0xfc00) == 0xdc00
    ) {
      // Surrogate Pair
      c = 0x10000 + ((c & 0x03ff) << 10) + (str.charCodeAt(++i) & 0x03ff);
      out[p++] = (c >> 18) | 240;
      out[p++] = ((c >> 12) & 63) | 128;
      out[p++] = ((c >> 6) & 63) | 128;
      out[p++] = (c & 63) | 128;
    } else {
      out[p++] = (c >> 12) | 224;
      out[p++] = ((c >> 6) & 63) | 128;
      out[p++] = (c & 63) | 128;
    }
  }
  return out;
}

function utf8ByteArrayToString(bytes) {
  // array of bytes
  var out = [],
    pos = 0,
    c = 0;
  while (pos < bytes.length) {
    var c1 = bytes[pos++];
    if (c1 < 128) {
      out[c++] = String.fromCharCode(c1);
    } else if (c1 > 191 && c1 < 224) {
      var c2 = bytes[pos++];
      out[c++] = String.fromCharCode(((c1 & 31) << 6) | (c2 & 63));
    } else if (c1 > 239 && c1 < 365) {
      // Surrogate Pair
      var c2 = bytes[pos++];
      var c3 = bytes[pos++];
      var c4 = bytes[pos++];
      var u =
        (((c1 & 7) << 18) | ((c2 & 63) << 12) | ((c3 & 63) << 6) | (c4 & 63)) -
        0x10000;
      out[c++] = String.fromCharCode(0xd800 + (u >> 10));
      out[c++] = String.fromCharCode(0xdc00 + (u & 1023));
    } else {
      var c2 = bytes[pos++];
      var c3 = bytes[pos++];
      out[c++] = String.fromCharCode(
        ((c1 & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63)
      );
    }
  }
  return out.join("");
}

var b64_table =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

function b64_encode(data) {
  var o1,
    o2,
    o3,
    h1,
    h2,
    h3,
    h4,
    bits,
    r,
    i = 0,
    enc = "";
  if (!data) {
    return data;
  }
  do {
    o1 = data[i++];
    o2 = data[i++];
    o3 = data[i++];
    bits = (o1 << 16) | (o2 << 8) | o3;
    h1 = (bits >> 18) & 0x3f;
    h2 = (bits >> 12) & 0x3f;
    h3 = (bits >> 6) & 0x3f;
    h4 = bits & 0x3f;
    enc +=
      b64_table.charAt(h1) +
      b64_table.charAt(h2) +
      b64_table.charAt(h3) +
      b64_table.charAt(h4);
  } while (i < data.length);
  r = data.length % 3;
  return (r ? enc.slice(0, r - 3) : enc) + "===".slice(r || 3);
}

function b64_decode(data) {
  var o1,
    o2,
    o3,
    h1,
    h2,
    h3,
    h4,
    bits,
    i = 0,
    result = [];
  if (!data) {
    return data;
  }
  data += "";
  do {
    h1 = b64_table.indexOf(data.charAt(i++));
    h2 = b64_table.indexOf(data.charAt(i++));
    h3 = b64_table.indexOf(data.charAt(i++));
    h4 = b64_table.indexOf(data.charAt(i++));
    bits = (h1 << 18) | (h2 << 12) | (h3 << 6) | h4;
    o1 = (bits >> 16) & 0xff;
    o2 = (bits >> 8) & 0xff;
    o3 = bits & 0xff;
    result.push(o1);
    if (h3 !== 64) {
      result.push(o2);
      if (h4 !== 64) {
        result.push(o3);
      }
    }
  } while (i < data.length);
  return result;
}

function rand(min, max) {
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

function randString(n) {
  var r = "";
  for (var i = 0; i < n; i++) r += String.fromCharCode(rand(1, 65535));

  return r;
}

function xor_encrypt(key, data, seed) {
  if (typeof seed == "undefined") seed = randString(32);

  var d = stringToUtf8ByteArray(seed + String.fromCharCode(0) + data),
    k = stringToUtf8ByteArray(key),
    r = [];

  for (var i = 0; i < d.length; i++)
    r[i] = r[i - 1] ^ d[i] ^ k[Math.floor(i % k.length)];

  return r;
}

function xor_decrypt(key, data) {
  var d = data,
    k = stringToUtf8ByteArray(key),
    r = [];

  for (var i = 0; i < d.length; i++)
    r[i] = d[i - 1] ^ d[i] ^ k[Math.floor(i % k.length)];

  r.splice(0, r.indexOf(0) + 1);
  return utf8ByteArrayToString(r);
}

  export default XORCipher;