php 根据输入的参数，获取上季度最后一个月的时间

public function getTime( $time ='2017-06-01 00:00:00'){

    $month = date('m',strtotime($time));
    $season = ceil($month/3);//当月是第几季度
    $yeah =date('Y',strtotime($time)) ;
    if($season ==1){
        $oldYeah =  intval($yeah-1) ;

        $newTimeStart = $oldYeah."-12-01 00:00:00";
        $newTimeEnd = $oldYeah."-12-31 23:59:59";
    }else{
        $newTimeStart =  date('Y-m-d H:i:s',mktime(0, 0, 0,$season*3-3,1,date($yeah)));
        $newTimeEnd =  date('Y-m-d H:i:s',mktime(23,59,59,$season*3-3,date('t',mktime(0, 0, 0,$season*3-3,1,date($yeah))),date($yeah)));
    }
    var_dump($newTimeStart,$newTimeEnd);exit;
}