<?php 
header('Content-Type: text/html; charset=utf-8');

class DateAgo {
	
	public $date;

	public function ago() 
	{
	    $now = new DateTime;
	    $ago = new DateTime($this->date);
	    $diff = $now->diff($ago);

	    $diff->w = floor($diff->d / 7);
	    $diff->d -= $diff->w * 7;

	    $string = array(
	        'y' => 'yıl',
	        'm' => 'ay',
	        'w' => 'hafta',
	        'd' => 'gün',
	        'h' => 'saat',
	        'i' => 'dakika',
	        's' => 'saniye',
	    );
	    foreach ($string as $k => &$v) 
	    {
	        if ($diff->$k) {
	            $v = $diff->$k . ' ' . $v . ($diff->$k > 1 ? '' : '');
	        } else {
	            unset($string[$k]);
	        }
	    }
	    return $string ? implode(', ', $string) . ' önce' : 'şimdi';
	}
}

$ago = new DateAgo();
$ago->date = "12.05.2016 18:20:50";
echo $ago->ago();