php n일전, n시간전 날짜 차이 계산하기

function beforeDate($date) {
  $now = strtotime(date("Y-m-d H:i:s"));
  $postDate = strtotime($date);
  $dtDiff = $now - $postDate;

  $rs = 0;
  if($dtDiff < 20)  $rs = '방금 전';
  else if($dtDiff < 60) $rs = floor($dtDiff) . "초 전";
  else if($dtDiff < 60*60) $rs = floor($dtDiff / 60) . "분 전";
  else if($dtDiff < 60*60*24) $rs = floor($dtDiff / (60*60)) . "시간 전";
  else if($dtDiff < 60*60*24*7) $rs = floor($dtDiff / (60*60*24)) . "일 전";
  else if($dtDiff < 60*60*24*30) $rs = floor($dtDiff / (60*60*24*7)) . "주 전";
  else if($dtDiff < 60*60*24*365) $rs = floor($dtDiff / (60*60*24*30)) . "달 전";
  else $rs = floor($dtDiff / (60*60*24*365)) . "년 전";
  return $rs;
}