define(function () {
  'use strict';

  /*
    reimplate after node-deb-version-compare under MIT
    (https://github.com/sdumetz/node-deb-version-compare)
  */

  function Version(v) {
    var version = /^[a-zA-Z]?([0-9]*(?=:))?:(.*)/.exec(v);
    this.epoch = (version) ? version[1] : 0;
    version = (version && version[2]) ? version[2] : v;
    version = version.split('-');
    this.debian = (version.length > 1) ? version.pop() : '';
    this.upstream = version.join('-');
  }

  Version.prototype.compare = function (b) {
    if ((this.epoch > 0 || b.epoch > 0) && Math.sign(this.epoch - b.epoch) !== 0) {
      return Math.sign(this.epoch - b.epoch);
    }
    if (this.compareStrings(this.upstream, b.upstream) !== 0) {
      return this.compareStrings(this.upstream, b.upstream);
    }
    return this.compareStrings(this.debian, b.debian);
  };

  Version.prototype.charCode = function (c) { // the lower the charcode the lower the version.
    // if (c === '~') {return 0;} // tilde sort before anything
    // else
    if (/[a-zA-Z]/.test(c)) {
      return c.charCodeAt(0) - 'A'.charCodeAt(0) + 1;
    } else if (/[.:+-:]/.test(c)) {
      return c.charCodeAt(0) + 'z'.charCodeAt(0) + 1;
    } // charcodes are 46..58
    return 0;
  };

  // find index of "val" in "ar".
  Version.prototype.findIndex = function (ar, fn) {
    for (var i = 0; i < ar.length; i++) {
      if (fn(ar[i], i)) {
        return i;
      }
    }
    return -1;
  };

  Version.prototype.compareChunk = function (a, b) {
    var ca = a.split('');
    var cb = b.split('');
    var diff = this.findIndex(ca, function (c, index) {
      if (cb[index] && c === cb[index]) {
        return false;
      }
      return true;
    });
    if (diff === -1) {
      if (cb.length > ca.length) {
        if (cb[ca.length] === '~') {
          return 1;
        }
        return -1;
      }
      return 0; // no diff found and same length
    } else if (!cb[diff]) {
      return (ca[diff] === '~') ? -1 : 1;
    }
    return (this.charCode(ca[diff]) > this.charCode(cb[diff])) ? 1 : -1;
  };

  Version.prototype.compareStrings = function (a, b) {
    if (a === b) {
      return 0;
    }
    var parseA = /([^0-9]+|[0-9]+)/g;
    var parseB = /([^0-9]+|[0-9]+)/g;
    var ra = parseA.exec(a);
    var rb = parseB.exec(b);
    while (ra !== null && rb !== null) {
      if ((isNaN(ra[1]) || isNaN(rb[1])) && ra[1] !== rb[1]) { // a or b is not a number and they're not equal. Note : "" IS a number so both null is impossible
        return this.compareChunk(ra[1], rb[1]);
      } // both are numbers
      if (ra[1] !== rb[1]) {
        return (parseInt(ra[1], 10) > parseInt(rb[1], 10)) ? 1 : -1;
      }
      ra = parseA.exec(a);
      rb = parseB.exec(b);
    }
    if (!ra && rb) { // rb doesn't get exec-ed when ra == null
      return (parseB.exec(b)[1].split('')[0] === '~') ? 1 : -1;
    } else if (ra && !rb) {
      return (ra[1].split('')[0] === '~') ? -1 : 1;
    }
    return 0;
  };
  return function compare(a, b) {
    var va = new Version(a[0]);
    var vb = new Version(b[0]);
    return vb.compare(va);
  };
});