Pass time and get result in seconds

getSeconds.php

function getSeconds(string $time){              // $time is either 18:00 or "2 hours"
    if(preg_match("/(2[0-3]|[01][0-9]):([0-5][0-9])/", $time)){ // ^
        $format = 'Y-m-d H:i:s';
        $now = new \DateTimeImmutable();
        $future = new \DateTimeImmutable(date($format, strtotime($time)));
        $h = ( ($t = $future->format('H')) == '00') ? 24 : $t;
        $f = ( ($z = $now->format('H')) == '00') ? 24 : $z;
        $d = $h - $f;
        return $d * 3600 ?? false;
    }

    $items = explode(" ", $time);
    $parameter = array_values($items); // [ 0 => "2", 1 => "hours" ]

    foreach ($parameter as $key => $format){
        if( strpos($time, $format) !== false
            && is_numeric( $t = trim(str_replace($format, "", $time)) ) === true
        ){
            switch ($format){
                case 'second': case 'seconds': break;
                case 'minute': case 'minutes': $t = $t  * 60; break;
                case 'hour': case 'hours': $t = $t * 60 * 60; break;
                case 'day' : case 'days': $t = $t * 60 * 60 * 24; break;
                default: $t = false;
            }
        }
    }
    return $t ?? false;
}