trigger updateRegStatusOnClassCompletion on Registration__c (before insert, before update) {
//NOTE: need to consider both insert where class is already completed (because of walk-in) and 

    Map<ID, Schema.RecordTypeInfo> rtMap = Schema.SObjectType.Registration__c.getRecordTypeInfosById();
    
    for(Registration__c classReg : Trigger.new)
    {
        // when inserted, check if already completed; when updated, check if class completion changed and is yes or exemption
        if (Trigger.isInsert) {  // inserting new records, check if already completed
            //Check if the class has been attended or exempted
            if (classReg.Class_Completed__c != 'Yes' && classReg.Class_Completed__c != 'Exemption') {
                return;
            }
        } else if (Trigger.isUpdate) {  // if the class completion status has not changed, do not continue 
            Registration__c oldClassReg = Trigger.oldMap.get(classReg.Id);
            if (classReg.Class_Completed__c == oldClassReg.Class_Completed__c ) {
                return;
            } else if (classReg.Class_Completed__c == 'No' && oldClassReg.Class_Completed__c != 'Yes' && oldClassReg.Class_Completed__c != 'Exemption') {  //also exit trigger if status changed to no but was blank (effectively not changing)
                return;
            }
        }
        
        // get contact related to registration
        Contact oContact = New Contact();
        
        List<Contact> lContacts = [Select c.Id, c.Email, c.LevelOne_Training_Date__c, c.LevelOne_Training_Completed__c,
                                   c.LevelTwo_Training_Completed__c, c.LevelOne_Status__c,
                                   c.LevelTwo_Status__c, c.LevelThree_Status__c, c.Is_a_member__c, c.Member_Status__c,
                                   c.Has_Registered_for_LevelOne_Training__c , c.Has_Registered_for_LevelTwo_Training__c , c.Has_Registered_for_LevelThree_Training__c 
                                   From Contact c Where c.Id = :classReg.Contact__c];
        
        if (lContacts.size() > 0) {
            //Get the matching contact
            oContact = lContacts.get(0);
            
            //Determine class registration tier
            String recordType = rtMap.get(classReg.RecordTypeId).getName();
            
            // continue and make sure class has been completed
            if (classReg.Class_Completed__c == 'Yes' || classReg.Class_Completed__c == 'Exemption') {
                    
                String classStatus = (classReg.Class_Completed__c == 'Exemption') ? 'Exempt' : 'Attended';
                
                if (recordType == 'Level One Registration') {
                    // Set Date, Boolean and Status for Level One Class Attendance and Approve Level Two
                    oContact.LevelOne_Training_Completed__c = true;
                    ocontact.LevelOne_Status__c = classStatus;
                    if (oContact.LevelTwo_Status__c <> 'Attended') {
                        oContact.LevelTwo_Status__c = 'Approved';
                    }    
                } else if (recordType == 'Level Two Registration') {
                    // Set Boolean and Status for Level Two Class Attendance
                    oContact.LevelTwo_Training_Completed__c = true;
                    ocontact.LevelTwo_Status__c = classStatus;
                    
                    // Approve Level Three ONLY if contact is a member 
                    if ((ocontact.Member_Status__c == 'Yes' || oContact.Member_Status__c == 'Exempt' ) && oContact.LevelThree_Status__c <> 'Attended') {
                        oContact.LevelThree_Status__c = 'Approved';
                    }
                    
                } else if (recordType == 'Level Three Registration') {
                    // Set Status for Level Three Class Attendance
                    ocontact.LevelThree_Status__c = classStatus;
                }
                
            // ROLLBACK attendance and approval statuses if class status changes and is now 'No' 
            } else if (classReg.Class_Completed__c == 'No') {
                
                if (recordType == 'Level One Registration') {
                    // Roll Back to Registered (Level One) or Approved instead of Attended if class completed changes to No 
                    oContact.LevelOne_Training_Completed__c = false;
                    ocontact.LevelOne_Status__c = 'Registered';
                    
                    if (oContact.LevelTwo_Status__c <> 'Attended') {
                        //Check if they have registered for Level Two and if not set blank instead of 'Registered'
                        if (oContact.Has_Registered_for_LevelTwo_Training__c == true) {
                            oContact.LevelTwo_Status__c = 'Registered';
                        } else {
                            oContact.LevelTwo_Status__c = '';
                        }
                    }    
                } else if (recordType == 'Level Two Registration') {
                    // Set Boolean and Status for Level Two Class Attendance
                    oContact.LevelTwo_Training_Completed__c = false;
                    
                    // Check that Level Two should be Approved, otherwise roll back to Registered
                    if (oContact.LevelOne_Training_Completed__c == true) {
                        ocontact.LevelTwo_Status__c = 'Approved';
                    } else {
                        ocontact.LevelTwo_Status__c = 'Registered';
                    }
                    
                    
                    if (oContact.LevelThree_Status__c <> 'Attended') {
                        //Check if they have registered for Level Three and if not set blank instead of 'Registered'
                        if (oContact.Has_Registered_for_LevelThree_Training__c == true) {
                            oContact.LevelThree_Status__c = 'Registered';
                        } else {
                            oContact.LevelThree_Status__c = '';
                        }
                    }   
                    
                } else if (recordType == 'Level Three Registration') {
                    // Check that Level Three should be Approved, otherwise roll back to Registered
                    if (oContact.LevelTwo_Training_Completed__c == true) {
                        ocontact.LevelThree_Status__c = 'Approved';
                    } else {
                        ocontact.LevelThree_Status__c = 'Registered';
                    }
                }

            }
            
            //Update the Contact
            try {
                update oContact;
            } catch(DmlException e) {
                System.debug('Contact could not be updated.  The following exception occurred: ' + e.getMessage());
            }
            
            
        }
        
    }
    

}