this is a php complete Japanese system

class Calendar {
            public function __construct(){
              $this->naviHref = htmlentities($_SERVER["PHP_SELF"]);
            }
            /********************* PROPERTY ********************/
            private $dayLabels = array("","","","","","","");
            private $currentYear=0;
            private $currentMonth=0;
            private $currentDay=0;
            private $currentDate=null;
            private $daysInMonth=0;
            private $naviHref= null;
            /********************* PUBLIC **********************/
            public function show() {
              @$year  == null;
              @$month == null;
              if(null==@$year&&isset($_GET["year"])){
                @$year = $_GET["year"];
              }else if(null==@$year){
                @$year = date("Y",time());
              }
              if(null==@$month&&isset($_GET["month"])){
                $month = $_GET["month"];
              }else if(null==@$month){
                $month = date("m",time());
              }
              $this->currentYear=$year;
              $this->currentMonth=$month;
              $this->daysInMonth=$this->_daysInMonth($month,$year);
              $content="<div id="calendar">".
                "<div class="box">".
                $this->_createNavi().
                "</div>".
                "<div class="box-content">".
                  "<ul class="label">".$this->_createLabels()."</ul>";
                  $content.="<div class="clear"></div>";
                  $content.="<ul class="dates">";

                  $weeksInMonth = $this->_weeksInMonth($month,$year);
                  // Create weeks in a month
                  for( $i=0; $i<$weeksInMonth; $iPP ){

                    //Create days in a week
                    for($j=1;$j<=7;$jPP){
                      $content.=$this->_showDay($i*7+$j);
                    }
                  }
                  $content.="</ul>";
                  $content.="<div class="clear"></div>";
                $content.="</div>";
              $content.="</div>";
              return $content;
            }

            /********************* PRIVATE **********************/

            private function _showDay($cellNumber){
              if($this->currentDay==0){
                $firstDayOfTheWeek = date("N",strtotime($this->currentYear."-".$this->currentMonth."-01"));
                if(intval($cellNumber) == intval($firstDayOfTheWeek)){
                  $this->currentDay=1;
                }
              }

              if(($this->currentDay!=0)&&($this->currentDay<=$this->daysInMonth)){
                  $this->currentDate = date("Y-m-d",strtotime($this->currentYear."-".$this->currentMonth."-".($this->currentDay)));
                  $cellContent = $this->currentDay;
                  $this->currentDayPP;
              }else{
                  $this->currentDate =null;
                  $cellContent=null;
              }

              return "
              <li id="li-".$this->currentDate."" class="".($this->currentDate==date("Y-m-d")?"today":"")." relative ".($cellNumber%7==1?" start ":($cellNumber%7==0?" end ":" ")).
                ($cellContent==null?"mask":"")."">".($cellContent==null?"":"
                <span class="cellContent">".$cellContent."</span>

                <div class="avatar_review_layout">
                  <span data-today="".$cellContent."" data-date="".$this->currentDate.""
                  class="pointer relative addicon add_".$this->currentDate.""><span class="plus"></span></span>
                </div>
              ")."</li>";
            }

            private function _createNavi(){
              $nextMonth = $this->currentMonth==12?1:intval($this->currentMonth)+1;
              $nextYear = $this->currentMonth==12?intval($this->currentYear)+1:$this->currentYear;
              $preMonth = $this->currentMonth==1?12:intval($this->currentMonth)-1;
              $preYear = $this->currentMonth==1?intval($this->currentYear)-1:$this->currentYear;

              return
                "<div class="header">".
                  "<a class="prev" href="".$this->naviHref."?month=".sprintf("%02d",$preMonth)."&year=".$preYear.""> ".$preMonth." </a>".
                      "<span class="title">".date("Y  n ",strtotime($this->currentYear."-".$this->currentMonth."-1"))."</span>".
                  "<a class="next" href="".$this->naviHref."?month=".sprintf("%02d", $nextMonth)."&year=".$nextYear."">".$nextMonth."  </a>".
                "</div>";
            }

            private function _createLabels(){
              $content="";
              foreach($this->dayLabels as $index=>$label){
                $content.="<li class="".($label==6?"end title":"start title")." title">".$label."</li>";
              }
              return $content;
            }

            private function _weeksInMonth($month=null,$year=null){
              if( null==($year) ) {
                $year =  date("Y",time());
              }
              if(null==($month)) {
                $month = date("m",time());
              }
              // find number of days in this month
              $daysInMonths = $this->_daysInMonth($month,$year);
              $numOfweeks = ($daysInMonths%7==0?0:1) + intval($daysInMonths/7);
              $monthEndingDay= date("N",strtotime($year."-".$month."-".$daysInMonths));
              $monthStartDay = date("N",strtotime($year."-".$month."-01"));
              if($monthEndingDay<$monthStartDay){
                $numOfweeksPP;
              }
              return $numOfweeks;
            }

            private function _daysInMonth($month=null,$year=null){
              if(null==($year))
                $year =  date("Y",time());
              if(null==($month))
                $month = date("m",time());
              return date("t",strtotime($year."-".$month."-01"));
            }
        }

        $calendar = new Calendar();
        echo $calendar->show();

one of the paragraphs return is:

return "
              <li id="li-".$this->currentDate."" class="".($this->currentDate==date("Y-m-d")?"today":"")." relative ".($cellNumber%7==1?" start ":($cellNumber%7==0?" end ":" ")).
                ($cellContent==null?"mask":"")."">".($cellContent==null?"":"
                <span class="cellContent">".$cellContent."</span>

                <div class="avatar_review_layout">
                  <span data-today="".$cellContent."" data-date="".$this->currentDate.""
                  class="pointer relative addicon add_".$this->currentDate.""><span class="plus"></span></span>
                  // 
                </div>
              ")."</li>";

I want to put

foreach($driver_shift_get_all->{"driver-shifts"} as $value):
  echo "<br>".$value->date."<br>";
  print_r($value->{"drivers-available"});
endforeach;

join this return
but cannot join. There will be all kinds of problems
how can this be solved?