English representation of a past date

Function given below returns an english representation of a past date within the last month.

function time2str($ts)
{
 if(!ctype_digit($ts))
  $ts = strtotime($ts);

 $diff = time() - $ts;
 if($diff == 0)
  return 'now';
 elseif($diff > 0)
 {
  $day_diff = floor($diff / 86400);
  if($day_diff == 0)
  {
   if($diff < 60) return 'just now';
   if($diff < 120) return '1 minute ago';
   if($diff < 3600) return floor($diff / 60) . ' minutes ago';
   if($diff < 7200) return '1 hour ago';
   if($diff < 86400) return floor($diff / 3600) . ' hours ago';
  }
  if($day_diff == 1) return 'Yesterday';
  if($day_diff < 7) return $day_diff . ' days ago';
  if($day_diff < 31) return ceil($day_diff / 7) . ' weeks ago';
  if($day_diff < 60) return 'last month';
  return date('F Y', $ts);
 }
 else
 {
  $diff = abs($diff);
  $day_diff = floor($diff / 86400);
  if($day_diff == 0)
  {
   if($diff < 120) return 'in a minute';
   if($diff < 3600) return 'in ' . floor($diff / 60) . ' minutes';
   if($diff < 7200) return 'in an hour';
   if($diff < 86400) return 'in ' . floor($diff / 3600) . ' hours';
  }
  if($day_diff == 1) return 'Tomorrow';
  if($day_diff < 4) return date('l', $ts);
  if($day_diff < 7 + (7 - date('w'))) return 'next week';
  if(ceil($day_diff / 7) < 4) return 'in ' . ceil($day_diff / 7) . ' weeks';
  if(date('n', $ts) == date('n') + 1) return 'next month';
  return date('F Y', $ts);
 }
}