Figure out the function of that trigger.

trigger MSD_TRG_USER_ENGAGE_PERMISSION_SET_AFTER_INSUP on User (after insert,after update) { List UserListToUpdate= new List(); List DeActivatedUser=new List(); if(Trigger.IsInsert) { for(User NewUser:Trigger.new) { if(NewUser.IsActive) { UserListToUpdate.add(NewUser); } } } if(Trigger.IsUpdate) { for(User UsersNewData:Trigger.new) { for(User UsersOldData:Trigger.old) { If((UsersNewData.Id==UsersOldData.Id)&&(UsersNewData.IsActive==false)&&(UsersOldData.IsActive==true)) { DeActivatedUser.add(UsersNewData); } else If((UsersNewData.Id==UsersOldData.Id)&&(UsersNewData.IsActive==true)&&(UsersOldData.IsActive==false)) { UserListToUpdate.add(UsersNewData); } else if((UsersNewData.Id==UsersOldData.Id)&&(UsersNewData.IsActive==true)&&(UsersOldData.Profile_Name_vod__c!=UsersNewData.Profile_Name_vod__c)) { UserListToUpdate.add(UsersNewData); } } } } if(DeActivatedUser.size()>0) { USER_ENGAGE_PERMISSION_AUTOMATION.removeEngage(DeActivatedUser); String S1=json.serialize(DeActivatedUser); USER_ENGAGE_PERMISSION_AUTOMATION.removePermission(S1); } if(UserListToUpdate.size()>0) { USER_ENGAGE_PERMISSION_AUTOMATION.setEngage(UserListToUpdate); String S2=json.serialize(UserListToUpdate); USER_ENGAGE_PERMISSION_AUTOMATION.setPermission(S2); } }