Function time ago cách đây

function human_difference($post_date) {
    $seconds_hours = 60*60;
    $hours_days = $seconds_hours*24;

    $today = date("Y-m-d");
    $timestamp = $today.' '.date("H:i:s");

    $difference = strtotime($timestamp)-strtotime($post_date);
    if ($difference>$hours_days) {
        $date1 = new DateTime(substr($post_date,0,10));
        $date2 = new DateTime($today);
        $since = $date2->diff($date1)->format("%d");
        if ($since==1) { $since .= ' day'; }
        else { $since .= ' days'; }
    } else if ($difference>$seconds_hours) {
        $since = floor($difference/$seconds_hours).' hours';
    } else {
        $since = floor($difference/60).' mins';//mins
    }

    return $since;
}

$post_date_time = get_the_date() . ' ' . get_the_time(); //Format this to m/d/Y H:i:s
echo human_difference($post_date_time); // x days or x hours or x minutes