過去の時間を計算する

/**
 *          $time       
 * @route('UserExercises/to_time')
 */
public function to_time($time)
{
    $t = time() - $time == 0 ? 1 : time() - $time;
    $f = array(
        '31536000' => ' ',
        '2592000' => '  ',
        '604800' => '  ',
        '86400' => ' ',
        '3600' => '  ',
        '60' => '  ',
        '1' => ' '
    );
    foreach ($f as $k => $v) {
        if (0 != $c = floor($t / (int)$k)) {
            return $c . $v . ' ';
        }
    }
}