PHP将日期转换为消息，例如昨天下午2点-反转strtotime

我正在尝试构建一个函数，该函数需要时间戳并生成基于"相对"字符串的日期，可能是反向strtotime!

Yesterday at 2pm
Yesterday at 3:15pm
Earlier Today at 9am
Today at 12pm
Today at 12:45pm
Tomorrow at 5pm
Monday at 9pm
Sunday at 12:55am
All dates older than a week:
Thu 7th Jul

我目前有以下代码，并想知道如何改进它?它似乎效率不高，而且缺少一些功能。你还有什么要说的吗?

  static public function timestampRelativeString($timestamp, $rounding=900) {
    if(!self::isValidTimeStamp($timestamp))
      return "Invalid Timestamp";
    //Round to (default) 15 mins
    $timestamp = floor($timestamp/$rounding)*$rounding;
    //Today
    if($timestamp<mktime(0, 0, 0, date("m"), date("d")-1, date("y")))
      return date("D jS M", $timestamp);
    elseif($timestamp<mktime(23, 59, 59, date("m"), date("d")-1, date("y")))
      return "Today at ".date("G:i", $timestamp);
    elseif($timestamp<time()))
      return "Earlier today at ".date("G:i", $timestamp);
    elseif($timestamp<mktime(23, 59, 59, date("m"), date("d"), date("y")))
      return "Today at ".date("G:i", $timestamp);
    elseif($timestamp<mktime(23, 59, 59, date("m"), date("d")+1, date("y"))) //Tomorrow
      return "Tomorrow at ".date("G:i", $timestamp);
    elseif($timestamp<mktime(23, 59, 59, date("m"), date("d")+7, date("y"))) //Next Week
      return "On ".date("l", $timestamp)." at ".date("G:i", $timestamp);
    else 
      return date("D jS M", $timestamp);
  }

有谁知道一个脚本已经这样做了吗?还是非常相似?

非常感谢你的时间，