trigger reScheduleLogBooks on Log_Book__c (after update) {
    
    Set<String> subjects = new Set<String>();
    Set<String> students = new Set<String>();
  
    Set<id> set1 = new Set<id>();
    List<Log_Book__c> lbDelList = new List<Log_Book__c>();
    List<Log_Book__c> lbdl = new List<Log_Book__c>();
    Set<String> weeks = new Set<String>(); 
    List<Weeks__c> weekList = Weeks__c.getAll().values();
    Map<Integer,weeks__c> weekMap = new Map<Integer,weeks__c>();
    List<Log_Book__c> listToUpdate = new List<Log_Book__c>();
    List<Log_Book__c> lstToAdd = new List<Log_Book__c>();
    Set<Log_Book__c> setLog = new Set<Log_Book__c>();
    
    for(weeks__c week : weekList)
    {
        weekMap.put((Integer)week.Order__c,week);
         
    }
    
    for(Log_Book__c lbook : Trigger.old)
    {
        set1.add(lbook.Id);
        subjects.add(lbook.Subject__c);
        students.add(lbook.Student__c);
    }
    lbdl=[select Abacus__c, Absent_Time_Stamp__c, Absent__c, Attended__c, Class_Scheduled_Date__c, Collected_Book__c, Comments__c, Do_Not_Promote__c, English__c, Level__c, Order__c, Reason__c, Id, Student__c, Subject__c, Subjects_Registered__c, Week__c, Week_Day__c, gk__c, math__c from log_book__c where id in: set1 AND Subject__c in: subjects AND Student__c in: students ];
    
    
    for(Log_Book__c lbdelete : lbdl)
    {
        if(lbdelete.Class_Scheduled_Date__c>System.Today())
        {
           lbDelList.add(lbdelete);
           system.debug('@@@@@@@@@@Deleted Record is@@@@@@'+lbDelList);
        }
           
    }
    if(lbDelList.size()>0 && lbDelList!=null)
    {
    
        delete lbDelList;
    }
    
    
    if(stoprecursive.trigger1==true)
    {
        stoprecursive.trigger1=false;
    for(Log_Book__c lbUpdate : Trigger.new)
    {
            weeks.add(lbUpdate.week__c);
            subjects.add(lbUpdate.Subject__c);
            students.add(lbUpdate.Student__c); 
    }
    
    for(Log_Book__c lbup : [select Abacus__c, Absent_Time_Stamp__c, Absent__c, Attended__c, Class_Scheduled_Date__c, Collected_Book__c, Comments__c, Do_Not_Promote__c, English__c, Level__c, Order__c, Reason__c, Id, Student__c, Subject__c, Subjects_Registered__c, Week__c, Week_Day__c, gk__c, math__c from log_book__c where subject__c IN: subjects AND Student__c IN: students AND week__c IN: weeks AND Class_Scheduled_Date__c >=: system.today() order by order__c])
      {
          Integer weekLevel = 0;     
          String[] weekLevels = lbup.Week__c.split('-');
          //will get only week number of week__c field of Log_Book__c object selected value will store in first index 
          weekLevel = Integer.valueof(weekLevels[0]);
   
      if(lbup.Class_Scheduled_Date__c >= System.Today())
       {
           for(Integer j=weekLevel;j<27;j++)
           {
           
            lbup.Class_Scheduled_Date__c = lbup.Class_Scheduled_Date__c.addDays(7);
           
            //assigning custom setting value to week__c field based on selected week number from log_book__c object
            lbup.week__c = weekMap.get(weekLevel).name;
            system.debug('*************'+lbup.Class_Scheduled_Date__c + lbup.Level__c + lbup.Week__c);
            //lstToAdd.add(lbup);
            lstToAdd.add(lbup);
            weekLevel++;
            }
            //lstToAdd.add(lbup);
            weekLevel = 1;
        }
      }
     setLog.addAll(lstToAdd);
     listToUpdate.addAll(setLog);
    }
   
    //stoprecursive.trigger1=true;
    //delete lbDelList;
    update listToUpdate;