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//     node-uuid/uuid.js
//
//     Copyright (c) 2010 Robert Kieffer
//     Dual licensed under the MIT and GPL licenses.
//     Documentation and details at https://github.com/broofa/node-uuid
(function() {
  var _global = this;

  // Unique ID creation requires a high quality random # generator, but
  // Math.random() does not guarantee "cryptographic quality".  So we feature
  // detect for more robust APIs, normalizing each method to return 128-bits
  // (16 bytes) of random data.
  var mathRNG, nodeRNG, whatwgRNG;

  // Math.random()-based RNG.  All platforms, very fast, unknown quality
  var _rndBytes = new Array(16);
  mathRNG = function() {
    var r, b = _rndBytes, i = 0;

    for (var i = 0, r; i < 16; i++) {
      if ((i & 0x03) == 0) r = Math.random() * 0x100000000;
      b[i] = r >>> ((i & 0x03) << 3) & 0xff;
    }

    return b;
  }

  // WHATWG crypto-based RNG - http://wiki.whatwg.org/wiki/Crypto
  // WebKit only (currently), moderately fast, high quality
  if (_global.crypto && crypto.getRandomValues) {
    var _rnds = new Uint32Array(4);
    whatwgRNG = function() {
      crypto.getRandomValues(_rnds);

      for (var c = 0 ; c < 16; c++) {
        _rndBytes[c] = _rnds[c >> 2] >>> ((c & 0x03) * 8) & 0xff;
      }
      return _rndBytes;
    }
  }

  // Node.js crypto-based RNG - http://nodejs.org/docs/v0.6.2/api/crypto.html
  // Node.js only, moderately fast, high quality
  try {
    var _rb = require('crypto').randomBytes;
    nodeRNG = _rb && function() {
      return _rb(16);
    };
  } catch (e) {}

  // Select RNG with best quality
  var _rng = nodeRNG || whatwgRNG || mathRNG;

  // Buffer class to use
  var BufferClass = typeof(Buffer) == 'function' ? Buffer : Array;

  // Maps for number <-> hex string conversion
  var _byteToHex = [];
  var _hexToByte = {};
  for (var i = 0; i < 256; i++) {
    _byteToHex[i] = (i + 0x100).toString(16).substr(1);
    _hexToByte[_byteToHex[i]] = i;
  }

  // **`parse()` - Parse a UUID into it's component bytes**
  function parse(s, buf, offset) {
    var i = (buf && offset) || 0, ii = 0;

    buf = buf || [];
    s.toLowerCase().replace(/[0-9a-f]{2}/g, function(oct) {
      if (ii < 16) { // Don't overflow!
        buf[i + ii++] = _hexToByte[oct];
      }
    });

    // Zero out remaining bytes if string was short
    while (ii < 16) {
      buf[i + ii++] = 0;
    }

    return buf;
  }

  // **`unparse()` - Convert UUID byte array (ala parse()) into a string**
  function unparse(buf, offset) {
    var i = offset || 0, bth = _byteToHex;
    return  bth[buf[i++]] + bth[buf[i++]] +
            bth[buf[i++]] + bth[buf[i++]] + '-' +
            bth[buf[i++]] + bth[buf[i++]] + '-' +
            bth[buf[i++]] + bth[buf[i++]] + '-' +
            bth[buf[i++]] + bth[buf[i++]] + '-' +
            bth[buf[i++]] + bth[buf[i++]] +
            bth[buf[i++]] + bth[buf[i++]] +
            bth[buf[i++]] + bth[buf[i++]];
  }

  // **`v1()` - Generate time-based UUID**
  //
  // Inspired by https://github.com/LiosK/UUID.js
  // and http://docs.python.org/library/uuid.html

  // random #'s we need to init node and clockseq
  var _seedBytes = _rng();

  // Per 4.5, create and 48-bit node id, (47 random bits + multicast bit = 1)