function pretty_dates() {
    var dates = document.getElementsByTagName('span');
    for (var i = 0; i < dates.length; i++) {
        if (dates[i].title && dates[i].className && dates[i].className.indexOf('date') >= 0) {
            var date = pretty_date(dates[i].title);
            if (date) dates[i].innerHTML = date;
        }
    }
}

function pretty_date(date_str) {
  var time = ('' + date_str).replace(/-/g,"/").replace(/[TZ]/g," ");
  var seconds = (new Date() - new Date(time)) / 1000;
  var token = 'ago', list_choice = 1;
  if (seconds < 0) {
    seconds = Math.abs(seconds);
    token = 'from now';
    list_choice = 2;
  }
  var i = 0, format;
  while (format = time_formats[i++]) if (seconds < format[0]) {
    if (typeof format[2] == 'string') return format[list_choice];
    else return Math.floor(seconds / format[2]) + ' ' + format[1] + ' ' + token;
  }
  return time;
};

var time_formats = [
  [60, 'just now', 1], // 60
  [120, '1 minute ago', '1 minute from now'], // 60*2
  [3600, 'minutes', 60], // 60*60, 60
  [7200, '1 hour ago', '1 hour from now'], // 60*60*2
  [86400, 'hours', 3600], // 60*60*24, 60*60
  [172800, 'yesterday', 'tomorrow'], // 60*60*24*2
  [604800, 'days', 86400], // 60*60*24*7, 60*60*24
  [1209600, 'last week', 'next week'], // 60*60*24*7*4*2
  [2419200, 'weeks', 604800], // 60*60*24*7*4, 60*60*24*7
  [4838400, 'last month', 'next month'], // 60*60*24*7*4*2
  [29030400, 'months', 2419200], // 60*60*24*7*4*12, 60*60*24*7*4
  [58060800, 'last year', 'next year'], // 60*60*24*7*4*12*2
  [2903040000, 'years', 29030400], // 60*60*24*7*4*12*100, 60*60*24*7*4*12
  [5806080000, 'last century', 'next century'], // 60*60*24*7*4*12*100*2
  [58060800000, 'centuries', 2903040000] // 60*60*24*7*4*12*100*20, 60*60*24*7*4*12*100
];

function app_init() {
    pretty_dates();
    setInterval(pretty_dates, 5000);
}