Help with formatting date string

I have an Event model with a start and end date (stored as timestamps).

What is the best way to produce a string describing the date of the event depending on a few factors, I have the beginnings of an if statement below, although I can see straight away that this will get out of hand.

The question relates to how best compare the dates and produce all possible outcomes.

    public function getDateTimeString()
    {
        $start = $this->started_at; // started_at is a timestamp on this Event model
        $end = $this->ended_at; // ended_at is a timestamp on this Event model
        
        if ( $start->isSameDay($end) ) {
            //    $dt->isYesterday(); - Produce something like "Yesterday between 09:00 and 10:00
            //    $dt->isToday(); "Earlier today from 09:00 - 10:00" or "Later today between 16:00 - 17:00" or "Started 30 minutes ago and ends at 17:00"
            //    $dt->isTomorrow(); ""Tomorrow from 09:00 until 10:00"
            //    $dt->isFuture(); "Fri 25 Mar 2016 from 09:00 - 10:00"
            //    $dt->isPast(); "Mon 21 Mar 2016 from 09:00 - 10:00"
            return "On " . $start->format("D d M Y") . " from " . $start->format("H:i") . " until " . $end->format("H:i");
        } else {
            // Same as above, but change the strings to use correct language
            return "From " . $start->format("H:i") . " on " . $start->format("D d M Y") . " until " . $end->format("H:i") . " on " . $end->format("D d M Y");
        }
    }