/**
 * 
 * @param obj the JSON data returned from Twitter api
 */
function twitterCallback(obj) {
  var twitters = obj;
  var statusHTML = "";
  var username = twitters[0].user.screen_name
  for (var i=0; i<twitters.length; i++){
    if(i == 0) {
      statusHTML += '<li class="first">';
    } else {
      statusHTML += '<li>';
    }
    statusHTML += ('<a href="http://www.twitter.com/' + username + '/statuses/' + twitters[i].id + '" target="_blank">'+twitters[i].text+"<span>" + relativeTime(twitters[i].created_at)+'</span></a></li>');
  }
  
  $('twitter').down('ul').innerHTML = statusHTML;
}

/**
 * Helper function to determine the relative time of
 * a Twitter post
 *
 * @param   time_value an absolute time of the tweet
 * @returns            a string representing the relative time
 */
function relativeTime(time_value) {
  var values = time_value.split(" ");
  time_value = values[1] + " " + values[2] + ", " + values[5] + " " + values[3];
  var parsed_date = Date.parse(time_value);
  var relative_to = (arguments.length > 1) ? arguments[1] : new Date();
  var delta = parseInt((relative_to.getTime() - parsed_date) / 1000);
  delta = delta + (relative_to.getTimezoneOffset() * 60);

  if (delta < 60) {
    return 'less than a minute ago';
  } else if(delta < 120) {
    return 'about a minute ago';
  } else if(delta < (60*60)) {
    return (parseInt(delta / 60)).toString() + ' minutes ago';
  } else if(delta < (120*60)) {
    return 'about an hour ago';
  } else if(delta < (24*60*60)) {
    return 'about ' + (parseInt(delta / 3600)).toString() + ' hours ago';
  } else if(delta < (48*60*60)) {
    return '1 day ago';
  } else {
    return (parseInt(delta / 86400)).toString() + ' days ago';
  }
}