// After including analytics.js, but before using it anywhere...

// Wrap identify so that all traits persist in a cookie, 
// and each call is merged with previously persisted traits
var identifyFn = analytics['identify'];
analytics['identify'] = function(){
  var new_traits,
      new_arguments = [],
      referrer_traits,
      id,
      old_traits,
      all_traits = {};
      
  // First arg might be the ID, or the attributes may be set anonymously
  if(arguments[0] && (typeof arguments[0] == 'string')){ 
    id = arguments.shift();
  }
  new_traits = arguments[0];
  
  // Collect existing and previous traits together
  old_traits = _.extend({}, JSON.parse($.cookie('analytics_user_traits')));
  all_traits = _.extend({}, old_traits, new_traits);

  // Also collect and merge referrers and campaigns
  referrer_traits = getReferrerTraits();
  all_traits = _.extend({}, all_traits, referrer_traits);

  // Persist traits for next time
  $.cookie("analytics_user_traits", JSON.stringify(all_traits));
  
  // identify the user with all traits to the analytics services
  if(typeof id == 'string') { new_arguments.push(id); }
  new_arguments.push(all_traits);
  identifyFn.apply(identifyFn, new_arguments);
};