check if given date time is of today or yesterday php

1function getRangeDateString($timestamp) {
2    if ($timestamp) {
3        $currentTime=strtotime('today');
4        // Reset time to 00:00:00
5        $timestamp=strtotime(date('Y-m-d 00:00:00',$timestamp));
6        $days=round(($timestamp-$currentTime)/86400);
7        switch($days) {
8            case '0';
9                return 'Today';
10                break;
11            case '-1';
12                return 'Yesterday';
13                break;
14            case '-2';
15                return 'Day before yesterday';
16                break;
17            case '1';
18                return 'Tomorrow';
19                break;
20            case '2';
21                return 'Day after tomorrow';
22                break;
23            default:
24                if ($days > 0) {
25                    return 'In '.$days.' days';
26                } else {
27                    return ($days*-1).' days ago';
28                }
29                break;
30        }
31    }
32}
33