/**
 * Status of page load.
 */

var pageLoaded = false;

/**
 * Global reference.
 */

var global = 'undefined' != typeof window ? window : global;

/**
 * Inheritance.
 *
 * @param {Function} ctor a
 * @param {Function} ctor b
 * @api private
 */

exports.inherits = function inherits (a, b) {
  function c () { }
  c.prototype = b.prototype;
  a.prototype = new c;
};

/**
 * Object.keys
 */

exports.keys = Object.keys || function (obj) {
  var ret = [];
  var has = Object.prototype.hasOwnProperty;

  for (var i in obj) {
    if (has.call(obj, i)) {
      ret.push(i);
    }
  }

  return ret;
};

/**
 * Adds an event.
 *
 * @api private
 */

exports.on = function (element, event, fn, capture) {
  if (element.attachEvent) {
    element.attachEvent('on' + event, fn);
  } else if (element.addEventListener) {
    element.addEventListener(event, fn, capture);
  }
};

/**
 * Load utility.
 *
 * @api private
 */

exports.load = function (fn) {
  if (global.document && document.readyState === 'complete' || pageLoaded) {
    return fn();
  }

  exports.on(global, 'load', fn, false);
};

/**
 * Change the internal pageLoaded value.
 */

if ('undefined' != typeof window) {
  exports.load(function () {
    pageLoaded = true;
  });
}

/**
 * Defers a function to ensure a spinner is not displayed by the browser.
 *
 * @param {Function} fn
 * @api private
 */

exports.defer = function (fn) {
  if (!exports.ua.webkit || 'undefined' != typeof importScripts) {
    return fn();
  }

  exports.load(function () {
    setTimeout(fn, 100);
  });
};

/**
 * JSON parse.
 *
 * @see Based on jQuery#parseJSON (MIT) and JSON2
 * @api private
 */

var rvalidchars = /^[\],:{}\s]*$/
  , rvalidescape = /\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g
  , rvalidtokens = /"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g
  , rvalidbraces = /(?:^|:|,)(?:\s*\[)+/g
  , rtrimLeft = /^\s+/
  , rtrimRight = /\s+$/

exports.parseJSON = function (data) {
  if ('string' != typeof data || !data) {
    return null;
  }

  data = data.replace(rtrimLeft, '').replace(rtrimRight, '');

  // Attempt to parse using the native JSON parser first
  if (global.JSON && JSON.parse) {
    return JSON.parse(data);
  }

  if (rvalidchars.test(data.replace(rvalidescape, '@')
      .replace(rvalidtokens, ']')
      .replace(rvalidbraces, ''))) {
    return (new Function('return ' + data))();
  }
};

/**
 * UA / engines detection namespace.
 *
 * @namespace
 */

exports.ua = {};

/**
 * Whether the UA supports CORS for XHR.
 *
 * @api private
 */

exports.ua.hasCORS = 'undefined' != typeof XMLHttpRequest && (function () {
  try {
    var a = new XMLHttpRequest();
  } catch (e) {
    return false;
  }

  return a.withCredentials != undefined;
})();

/**
 * Detect webkit.
 *
 * @api private
 */

exports.ua.webkit = 'undefined' != typeof navigator &&
  /webkit/i.test(navigator.userAgent);

/**
 * Detect gecko.
 *
 * @api private
 */

exports.ua.gecko = 'undefined' != typeof navigator &&
  /gecko/i.test(navigator.userAgent);

/**
 * Detect android;
 */

exports.ua.android = 'undefined' != typeof navigator &&
  /android/i.test(navigator.userAgent);

/**
 * Detect iOS.
 */

exports.ua.ios = 'undefined' != typeof navigator &&
  /^(iPad|iPhone|iPod)$/.test(navigator.platform);
exports.ua.ios6 = exports.ua.ios && /OS 6_/.test(navigator.userAgent);

/**
 * XHR request helper.
 *
 * @param {Boolean} whether we need xdomain
 * @api private
 */

exports.request = function request (xdomain) {
  if ('undefined' != typeof process) {
    var XMLHttpRequest = require('xmlhttprequest').XMLHttpRequest;
    return new XMLHttpRequest();
  }

  if (xdomain && 'undefined' != typeof XDomainRequest && !exports.ua.hasCORS) {
    return new XDomainRequest();
  }

  // XMLHttpRequest can be disabled on IE
  try {
    if ('undefined' != typeof XMLHttpRequest && (!xdomain || exports.ua.hasCORS)) {
      return new XMLHttpRequest();
    }
  } catch (e) { }

  if (!xdomain) {
    try {
      return new ActiveXObject('Microsoft.XMLHTTP');
    } catch(e) { }
  }
};

/**
 * Parses an URI
 *
 * @author Steven Levithan <stevenlevithan.com> (MIT license)
 * @api private
 */

var re = /^(?:(?![^:@]+:[^:@\/]*@)([^:\/?#.]+):)?(?:\/\/)?((?:(([^:@]*)(?::([^:@]*))?)?@)?([^:\/?#]*)(?::(\d*))?)(((\/(?:[^?#](?![^?#\/]*\.[^?#\/.]+(?:[?#]|$)))*\/?)?([^?#\/]*))(?:\?([^#]*))?(?:#(.*))?)/;

var parts = [
    'source', 'protocol', 'authority', 'userInfo', 'user', 'password', 'host'
  , 'port', 'relative', 'path', 'directory', 'file', 'query', 'anchor'
];

exports.parseUri = function (str) {
  var m = re.exec(str || '')
    , uri = {}
    , i = 14;

  while (i--) {
    uri[parts[i]] = m[i] || '';
  }

  return uri;
};

/**
 * Compiles a querystring
 *
 * @param {Object}
 * @api private
 */

exports.qs = function (obj) {
  var str = '';

  for (var i in obj) {
    if (obj.hasOwnProperty(i)) {
      if (str.length) str += '&';
      str += i + '=' + encodeURIComponent(obj[i]);
    }
  }

  return str;
};