/*!
 * URI.js - Mutating URLs
 * IPv6 Support
 *
 * Version: 1.15.1
 *
 * Author: Rodney Rehm
 * Web: http://medialize.github.io/URI.js/
 *
 * Licensed under
 *   MIT License http://www.opensource.org/licenses/mit-license
 *   GPL v3 http://opensource.org/licenses/GPL-3.0
 *
 */

(function (root, factory) {
  'use strict';
  // https://github.com/umdjs/umd/blob/master/returnExports.js
  if (typeof exports === 'object') {
    // Node
    module.exports = factory();
  } else if (typeof define === 'function' && define.amd) {
    // AMD. Register as an anonymous module.
    define(factory);
  } else {
    // Browser globals (root is window)
    root.IPv6 = factory(root);
  }
}(this, function (root) {
  'use strict';

  /*
  var _in = "fe80:0000:0000:0000:0204:61ff:fe9d:f156";
  var _out = IPv6.best(_in);
  var _expected = "fe80::204:61ff:fe9d:f156";

  console.log(_in, _out, _expected, _out === _expected);
  */

  // save current IPv6 variable, if any
  var _IPv6 = root && root.IPv6;

  function bestPresentation(address) {
    // based on:
    // Javascript to test an IPv6 address for proper format, and to
    // present the "best text representation" according to IETF Draft RFC at
    // http://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-04
    // 8 Feb 2010 Rich Brown, Dartware, LLC
    // Please feel free to use this code as long as you provide a link to
    // http://www.intermapper.com
    // http://intermapper.com/support/tools/IPV6-Validator.aspx
    // http://download.dartware.com/thirdparty/ipv6validator.js

    var _address = address.toLowerCase();
    var segments = _address.split(':');
    var length = segments.length;
    var total = 8;

    // trim colons (:: or ::a:b:c… or …a:b:c::)
    if (segments[0] === '' && segments[1] === '' && segments[2] === '') {
      // must have been ::
      // remove first two items
      segments.shift();
      segments.shift();
    } else if (segments[0] === '' && segments[1] === '') {
      // must have been ::xxxx
      // remove the first item
      segments.shift();
    } else if (segments[length - 1] === '' && segments[length - 2] === '') {
      // must have been xxxx::
      segments.pop();
    }

    length = segments.length;

    // adjust total segments for IPv4 trailer
    if (segments[length - 1].indexOf('.') !== -1) {
      // found a "." which means IPv4
      total = 7;
    }

    // fill empty segments them with "0000"
    var pos;
    for (pos = 0; pos < length; pos++) {
      if (segments[pos] === '') {
        break;
      }
    }

    if (pos < total) {
      segments.splice(pos, 1, '0000');
      while (segments.length < total) {
        segments.splice(pos, 0, '0000');
      }

      length = segments.length;
    }

    // strip leading zeros
    var _segments;
    for (var i = 0; i < total; i++) {
      _segments = segments[i].split('');
      for (var j = 0; j < 3 ; j++) {
        if (_segments[0] === '0' && _segments.length > 1) {
          _segments.splice(0,1);
        } else {
          break;
        }
      }

      segments[i] = _segments.join('');
    }

    // find longest sequence of zeroes and coalesce them into one segment
    var best = -1;
    var _best = 0;
    var _current = 0;
    var current = -1;
    var inzeroes = false;
    // i; already declared

    for (i = 0; i < total; i++) {
      if (inzeroes) {
        if (segments[i] === '0') {
          _current += 1;
        } else {
          inzeroes = false;
          if (_current > _best) {
            best = current;
            _best = _current;
          }
        }
      } else {
        if (segments[i] === '0') {
          inzeroes = true;
          current = i;
          _current = 1;
        }
      }
    }

    if (_current > _best) {
      best = current;
      _best = _current;
    }

    if (_best > 1) {
      segments.splice(best, _best, '');
    }

    length = segments.length;

    // assemble remaining segments
    var result = '';
    if (segments[0] === '')  {
      result = ':';
    }

    for (i = 0; i < length; i++) {
      result += segments[i];
      if (i === length - 1) {
        break;
      }

      result += ':';
    }

    if (segments[length - 1] === '') {
      result += ':';
    }

    return result;
  }

  function noConflict() {
    /*jshint validthis: true */
    if (root.IPv6 === this) {
      root.IPv6 = _IPv6;
    }
  
    return this;
  }

  return {
    best: bestPresentation,
    noConflict: noConflict
  };
}));
