รบกวนช่วยอธิบายโค้ดให้หน่อยค่ะ

<?php
 
class leave{
         
          public $emp_id = "" ; //ID พนักงาน
          public $data_start = "";  //วันที่เริ่มลา
          public $data_end = ""; //วันที่สิ้นสุด
          public $leave_full = ""; //1=ลาเตมวัน 2=ลาครึ่งวันเช้า 3=ลาครึ่งวันบ่าย
          public $leave_type = ""; //ประเภทการลา
          public $day_move = array(); //เก็บวันที่ถูกลบออกเนื่อจากเป้นวันหยุด
          public $error = array(); //เก็บ error ต่างๆ
          public $results = array();
         
          public function Add(){
                   $day_n = $this->ClaimDays($this->data_start,$this->data_end);
                   $day_number = $day_n;
                   $day_n = $this->GetWeekend($day_n,$this->data_start);
                   $day_n = $this->GetHoliday($day_n,$this->data_start,$this->data_end);
                   $day_n = $this->GetOldLeave($this->emp_id,$day_n,$this->data_start,$this->data_end);
                   $day_n = $this->CulDay($day_n,$this->leave_full);
                   $day_n = $this->GetLeaveType($this->leave_type,$this->emp_id,$day_n,$this->data_start);
                  
                   $this->results["count_day"] = $day_n; //เช็ควันลางานเกินกำหนดโดยตรวจสอบจากประเภทการลาที่ลาเกินจากเงื่อนไขการลา
                   if($day_n <= '-1'){//($day_n <= '-1'){
                             $this->error[] = "ไม่สามารถลาได้ เนื่องจากวันลาเกิน";
                   }else{
                             $this->results["ok"] = true;
                             for($i=0;$i<=$day_number-1;$i++){
                                      $strStartDate = $this->data_start;
                                      $strNewDate = date("Y-m-d", strtotime("+".$i." day", strtotime($strStartDate)));
                                      if($this->day_move[$strNewDate]==""){
                                                $this->results["day"][] = $strNewDate;
                                      }
                             }
                   }
                  
                  
          }
         
          public function ClaimDays($day1,$day2){ //หาวันที่ห่างกัน
                   return round((strtotime($day2)-strtotime($day1))/(24*60*60),0)+1;
          }
         
          public function GetWeekend($day_n=0,$strStartDate=""){//หาวันหยุดของบริษัท
                   $sql = "SELECT * FROM weekend";
                   $query = mysql_query($sql);
                   $dbarr = mysql_fetch_array($query);
                   for($i=0;$i<=$day_n-1;$i++){
                             $strStartDate = $strStartDate;
                             $strNewDate = date("Y-m-d", strtotime("+".$i." day", strtotime($strStartDate)));
                             $strDay = date('l', strtotime($strNewDate));
                             $strDay = strtolower($strDay);
                             if($dbarr[$strDay]=="0"){
                                      $this->day_move[$strNewDate] = $strNewDate;
                                      $day_n = $day_n-1;
                             }
                   }
                  
                   return $day_n;
          }
         
          public function GetHoliday($day_n=0,$data_start="",$data_end=""){//หาวันหยุด
                   $sql = "SELECT * FROM holiday WHERE holiday_date BETWEEN '".$data_start."' AND '".$data_end."'";
                   $query = mysql_query($sql);
                   $day = array();
                   while($dbarr=mysql_fetch_array($query)){
                             $day[$dbarr["holiday_date"]] = $dbarr["holiday_date"];
                   }
                  
                   //
                   if(count($day)>0){
                             foreach($day as $val){
                             /////////////////////
                                      for($i=0;$i<=$day_n-1;$i++){
                                                $strStartDate = $data_start;
                                                $strNewDate = date("Y-m-d", strtotime("+".$i." day", strtotime($strStartDate)));
                                                if($val==$strNewDate AND $this->day_move[$strNewDate]=="" ){
                                                          $this->day_move[$strNewDate] = $strNewDate;
                                                          $day_n = $day_n-1;
                                                }
                                      }
                             ////////////////////  
                             }
                   }
                   //
                   return $day_n;
          }
         
         
 
public function GetOldLeave($emp_id="",$day_n=0,$data_start="",$data_end=""){//หาวันลากรณีมีในระบบแล้ว
                   $sql = "SELECT * FROM leave_detail WHERE leave_date BETWEEN '".$data_start."' AND '".$data_end."' AND emp_id='".$emp_id."'";
                   $query = mysql_query($sql);
                   while($dbarr=mysql_fetch_array($query)){
                             //
                             for($i=0;$i<=$day_n-1;$i++){
                                      $strStartDate = $data_start;
                                      $strNewDate = date("Y-m-d", strtotime("+".$i." day", strtotime($strStartDate)));
                                      if($dbarr['leave_date']==$strNewDate AND $this->day_move[$strNewDate]=="" AND ($dbarr["status"]=="0" OR $dbarr["status"]=="1")){
                                                $this->day_move[$strNewDate] = $strNewDate;
                                                $day_n = $day_n-1;
                                      }
                             }
                             //
                   }
                   return $day_n;
          }
         
          public function CulDay($day_n=0,$leave_full="1"){//คำนวนกรณีลาครึ่งวัน หรือเต็มวัน
                   if($leave_full=="1"){
                             $day_n = $day_n*1;
                   }else if($leave_full=="2" or $leave_full=="3"){
                             $day_n = $day_n*0.5;
                   }
                  
                   return $day_n;
          }
         
          public function GetLeaveType($type="",$emp_id="",$day_n=0,$data_start=""){//ตรวจสอบข้อมูลประเภทการลาว่าเกินกำหนดหรือยัง
                   $sql = "SELECT * FROM master_leave_type WHERE leave_type_id='".$type."'";
                   $query = mysql_query($sql);
                   $dbarr = mysql_fetch_array($query);
                   $leave_n = $dbarr["leave_number"];
                   $date_cut = date("Y")."-".str_pad($dbarr["leave_cut_month"],2,'0',STR_PAD_LEFT)."-".str_pad($dbarr["leave_cut_day"],2,'0',STR_PAD_LEFT);
                   $date_cut_old = (date("Y")-1)."-".str_pad($dbarr["leave_cut_month"],2,'0',STR_PAD_LEFT)."-".str_pad($dbarr["leave_cut_day"],2,'0',STR_PAD_LEFT);
                   $sql = "SELECT * FROM `leave` WHERE emp_id='".$emp_id."'
                                      AND leave_type='".$type."'
                                      AND leave_end_day <= '".$date_cut."'
                                      AND leave_end_day >= '".$date_cut_old."'";
                  
                   $query = mysql_query($sql);
                   $count_day = 0;
                   while($dbarr=mysql_fetch_array($query)){
                             if($dbarr["leave_status"]=="0" or $dbarr["leave_status"]=="1"){
                                      $count_day = $count_day+$dbarr["leave_n"];
                             }
                   }
                  
                   $count_day = $count_day+$day_n;
                  
                   $this->results["use_day"] = $day_n;
                  
                   $count_day = $leave_n-$count_day;
                   //$count_day = $count_day - 0.5;
                   return $count_day;
          }
}
 
?><?php
 
class leave{
         
          public $emp_id = "" ; //ID พนักงาน
          public $data_start = "";  //วันที่เริ่มลา
          public $data_end = ""; //วันที่สิ้นสุด
          public $leave_full = ""; //1=ลาเตมวัน 2=ลาครึ่งวันเช้า 3=ลาครึ่งวันบ่าย
          public $leave_type = ""; //ประเภทการลา
          public $day_move = array(); //เก็บวันที่ถูกลบออกเนื่อจากเป้นวันหยุด
          public $error = array(); //เก็บ error ต่างๆ
          public $results = array();
         
          public function Add(){
                   $day_n = $this->ClaimDays($this->data_start,$this->data_end);
                   $day_number = $day_n;
                   $day_n = $this->GetWeekend($day_n,$this->data_start);
                   $day_n = $this->GetHoliday($day_n,$this->data_start,$this->data_end);
                   $day_n = $this->GetOldLeave($this->emp_id,$day_n,$this->data_start,$this->data_end);
                   $day_n = $this->CulDay($day_n,$this->leave_full);
                   $day_n = $this->GetLeaveType($this->leave_type,$this->emp_id,$day_n,$this->data_start);
                  
                   $this->results["count_day"] = $day_n; //เช็ควันลางานเกินกำหนดโดยตรวจสอบจากประเภทการลาที่ลาเกินจากเงื่อนไขการลา
                   if($day_n <= '-1'){//($day_n <= '-1'){
                             $this->error[] = "ไม่สามารถลาได้ เนื่องจากวันลาเกิน";
                   }else{
                             $this->results["ok"] = true;
                             for($i=0;$i<=$day_number-1;$i++){
                                      $strStartDate = $this->data_start;
                                      $strNewDate = date("Y-m-d", strtotime("+".$i." day", strtotime($strStartDate)));
                                      if($this->day_move[$strNewDate]==""){
                                                $this->results["day"][] = $strNewDate;
                                      }
                             }
                   }
                  
                  
          }
         
          public function ClaimDays($day1,$day2){ //หาวันที่ห่างกัน
                   return round((strtotime($day2)-strtotime($day1))/(24*60*60),0)+1;
          }
         
          public function GetWeekend($day_n=0,$strStartDate=""){//หาวันหยุดของบริษัท
                   $sql = "SELECT * FROM weekend";
                   $query = mysql_query($sql);
                   $dbarr = mysql_fetch_array($query);
                   for($i=0;$i<=$day_n-1;$i++){
                             $strStartDate = $strStartDate;
                             $strNewDate = date("Y-m-d", strtotime("+".$i." day", strtotime($strStartDate)));
                             $strDay = date('l', strtotime($strNewDate));
                             $strDay = strtolower($strDay);
                             if($dbarr[$strDay]=="0"){
                                      $this->day_move[$strNewDate] = $strNewDate;
                                      $day_n = $day_n-1;
                             }
                   }
                  
                   return $day_n;
          }
         
          public function GetHoliday($day_n=0,$data_start="",$data_end=""){//หาวันหยุด
                   $sql = "SELECT * FROM holiday WHERE holiday_date BETWEEN '".$data_start."' AND '".$data_end."'";
                   $query = mysql_query($sql);
                   $day = array();
                   while($dbarr=mysql_fetch_array($query)){
                             $day[$dbarr["holiday_date"]] = $dbarr["holiday_date"];
                   }
                  
                   //
                   if(count($day)>0){
                             foreach($day as $val){
                             /////////////////////
                                      for($i=0;$i<=$day_n-1;$i++){
                                                $strStartDate = $data_start;
                                                $strNewDate = date("Y-m-d", strtotime("+".$i." day", strtotime($strStartDate)));
                                                if($val==$strNewDate AND $this->day_move[$strNewDate]=="" ){
                                                          $this->day_move[$strNewDate] = $strNewDate;
                                                          $day_n = $day_n-1;
                                                }
                                      }
                             ////////////////////  
                             }
                   }
                   //
                   return $day_n;
          }
         
         
 
public function GetOldLeave($emp_id="",$day_n=0,$data_start="",$data_end=""){//หาวันลากรณีมีในระบบแล้ว
                   $sql = "SELECT * FROM leave_detail WHERE leave_date BETWEEN '".$data_start."' AND '".$data_end."' AND emp_id='".$emp_id."'";
                   $query = mysql_query($sql);
                   while($dbarr=mysql_fetch_array($query)){
                             //
                             for($i=0;$i<=$day_n-1;$i++){
                                      $strStartDate = $data_start;
                                      $strNewDate = date("Y-m-d", strtotime("+".$i." day", strtotime($strStartDate)));
                                      if($dbarr['leave_date']==$strNewDate AND $this->day_move[$strNewDate]=="" AND ($dbarr["status"]=="0" OR $dbarr["status"]=="1")){
                                                $this->day_move[$strNewDate] = $strNewDate;
                                                $day_n = $day_n-1;
                                      }
                             }
                             //
                   }
                   return $day_n;
          }
         
          public function CulDay($day_n=0,$leave_full="1"){//คำนวนกรณีลาครึ่งวัน หรือเต็มวัน
                   if($leave_full=="1"){
                             $day_n = $day_n*1;
                   }else if($leave_full=="2" or $leave_full=="3"){
                             $day_n = $day_n*0.5;
                   }
                  
                   return $day_n;
          }
         
          public function GetLeaveType($type="",$emp_id="",$day_n=0,$data_start=""){//ตรวจสอบข้อมูลประเภทการลาว่าเกินกำหนดหรือยัง
                   $sql = "SELECT * FROM master_leave_type WHERE leave_type_id='".$type."'";
                   $query = mysql_query($sql);
                   $dbarr = mysql_fetch_array($query);
                   $leave_n = $dbarr["leave_number"];
                   $date_cut = date("Y")."-".str_pad($dbarr["leave_cut_month"],2,'0',STR_PAD_LEFT)."-".str_pad($dbarr["leave_cut_day"],2,'0',STR_PAD_LEFT);
                   $date_cut_old = (date("Y")-1)."-".str_pad($dbarr["leave_cut_month"],2,'0',STR_PAD_LEFT)."-".str_pad($dbarr["leave_cut_day"],2,'0',STR_PAD_LEFT);
                   $sql = "SELECT * FROM `leave` WHERE emp_id='".$emp_id."'
                                      AND leave_type='".$type."'
                                      AND leave_end_day <= '".$date_cut."'
                                      AND leave_end_day >= '".$date_cut_old."'";
                  
                   $query = mysql_query($sql);
                   $count_day = 0;
                   while($dbarr=mysql_fetch_array($query)){
                             if($dbarr["leave_status"]=="0" or $dbarr["leave_status"]=="1"){
                                      $count_day = $count_day+$dbarr["leave_n"];
                             }
                   }
                  
                   $count_day = $count_day+$day_n;
                  
                   $this->results["use_day"] = $day_n;
                  
                   $count_day = $leave_n-$count_day;
                   //$count_day = $count_day - 0.5;
                   return $count_day;
          }
}
 
?>

  เป็น class เกี่่ยวกับ วันหยุดพนักงานไหม เดาไม่ออก

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