Calculate Passed Time

function calculate_passed_time($date){

        $today = date('Y-m-d H:i:s'); // Bugünün tarihi
        $today_seconds = strtotime($today); // Bugünün tarihi - saniye cinsinden
        $date_seconds = strtotime($date); // Verilen parametre - saniye cinsinden
        $diff = $today_seconds - $date_seconds; // Aradaki fark - saniye cinsinden

        if($diff > 0 && $diff < 60){
            $passed_time = $diff." saniye";
        }else if($diff >= 60 && $diff < 60*60){
            $minute = floor($diff / 60);
            $passed_time = $minute." dakika";
        }else if($diff >= 60*60 && $diff < 60*60*24 ){
            $hour = floor($diff/60/60);
            $passed_time = $hour." saat";
        }else if($diff >= 60*60*24 && $diff < 60*60*24*7){
            $day = floor($diff/60/60/24);
            $passed_time = $day." gün";
        }else if($diff >= 60*60*24*7 && $diff < 60*60*24*30 ){
            $week = floor($diff/60/60/24/7);
            $passed_time = $week." hafta";
        }else if($diff >= 60*60*24*30 && $diff < 60*60*24*30*12 ){
            $month = floor($diff/60/60/24/30);
            $passed_time = $month." ay";
        }else if($diff >= 60*60*24*30*12){
            $year = floor($year/60/60/24/30/12);
            $passed_time = $year." yıl";
        }else{
            $passed_time = "Invalid Time Error";
        }

        return $passed_time;

    }

    echo calculate_passed_time('2017-07-25 15:12:15');