module.exports = {
  createUUID: function () {
    const _self = this;
    // Loose interpretation of the specification DCE 1.1: Remote Procedure Call
    // since JavaScript doesn't allow access to internal systems, the last 48 bits
    // of the node section is made up using a series of random numbers (6 octets long).
    //
    const dg = new Date(1582, 10, 15, 0, 0, 0, 0);
    const dc = new Date();
    const t = dc.getTime() - dg.getTime();
    const tl = _self.getIntegerBits(t, 0, 31);
    const tm = _self.getIntegerBits(t, 32, 47);
    const thv = _self.getIntegerBits(t, 48, 59) + '1'; // version 1, security version is 2
    const csar = _self.getIntegerBits(_self.rand(4095), 0, 7);
    const csl = _self.getIntegerBits(_self.rand(4095), 0, 7);
    // since detection of anything about the machine/browser is far to buggy,
    // include some more random numbers here
    // if NIC or an IP can be obtained reliably, that should be put in
    // here instead.
    const n = _self.getIntegerBits(_self.rand(8191), 0, 7) +
      _self.getIntegerBits(_self.rand(8191), 8, 15) +
      _self.getIntegerBits(_self.rand(8191), 0, 7) +
      _self.getIntegerBits(_self.rand(8191), 8, 15) +
      _self.getIntegerBits(_self.rand(8191), 0, 15); // this last number is two octets long
    return tl + tm + thv + csar + csl + n;
  },

  // Pull out only certain bits from a very large integer, used to get the time
  // code information for the first part of a UUID. Will return zero's if there
  // aren't enough bits to shift where it needs to.
  getIntegerBits: function (val, start, end) {
    const base16 = this.returnBase(val, 16);
    const quadArray = [];
    let quadString = '';
    let i = 0;
    for (i = 0; i < base16.length; i++) {
      quadArray.push(base16.substring(i, i + 1));
    }
    for (i = Math.floor(start / 4); i <= Math.floor(end / 4); i++) {
      if (!quadArray[i] || quadArray[i] == '') { quadString += '0'; } else { quadString += quadArray[i]; }
    }
    return quadString;
  },

  // Replaced from the original function to leverage the built in methods in
  // JavaScript. Thanks to Robert Kieffer for pointing this one out
  returnBase: function (number, base) {
    return (number).toString(base).toUpperCase();
  },

  // pick a random number within a range of numbers
  // int b rand(int a); where 0 <= b <= a
  rand: function (max) {
    return Math.floor(Math.random() * (max + 1));
  },
};
