Parse Email Service's Text attachment into Salesforce Record

global class AccountEmailService implements Messaging.InboundEmailHandler {
    public static Schema.DescribeSObjectResult objectDescribe = Account.getSObjectType().getDescribe();
    public static  Map<String, Schema.SObjectField> fields;
   
    static{
        fields = objectDescribe.fields.getMap();
    }
   
    global Messaging.InboundEmailResult handleInboundEmail(Messaging.InboundEmail email, Messaging.InboundEnvelope envelope) {
        Messaging.InboundEmailResult result = new Messaging.InboundEmailresult();
        
        List<String> recordDataLines = new List<String>();//store to CSV's each data lines
        Map<String, String> fieldNameToFieldType = new Map<String, String>();
        Map < String, Decimal> fieldNumberMap = new Map < String, Decimal>();//Store the Field API name and column no/position in text attachment
       
        try{
            //fetch metadata type
            for(Account_FieldMapping__mdt fieldMapping: [SELECT Id, MasterLabel, Field_API_Name__c,Column_Number__c from Account_FieldMapping__mdt]){
                
                fieldNumberMap.put(fieldMapping.Field_API_Name__c, fieldMapping.Column_Number__c);
            }
            List<Document> lstDocument = new List<Document>();
            Folder fd = [SELECT Id from Folder WHERE Name = 'My Folder Files'];
            //get the CSV attachment from email and store in recordDataLines
            for(Messaging.Inboundemail.TextAttachment att : email.textAttachments){
                recordDataLines = att.body.trim().split('\n');
                Document d = new Document();  
                d.Name = att.fileName;
                d.body = Blob.valueOf(att.body);          
                d.folderid = fd.Id;
               
                lstDocument.add(d);
            }
            insert lstDocument;
           
            List<Account> lstAccount = new List<Account> ();
            //get the data from 2nd row
            for (Integer i = 0; i < recordDataLines.size(); i++) {
                List<String> csvRecordData = recordDataLines[i].split(',');
                Account objAcc = new Account();
               
                //iterate over each field and based on their data type store in the Service_Time_Entry__c fields
                for (String fieldName: fieldNumberMap.KeySet()) {
                   
                    Integer fieldNumber = Integer.valueOf(fieldNumberMap.get(fieldName));
                    fieldMapping( fieldNumber,  csvRecordData[fieldNumber],  fieldName, fieldNameToFieldType, objAcc );
                } 
				lstAccount.add(objAcc)
            }
            insert lstAccount;
           
           
        }
        catch(Exception e){
            System.debug('========='+e.getMessage());
        }
        return result;
    }
    //based on the field data type convert the data and save in Account
    public static void fieldMapping(Integer fieldNumber, String fieldValue, String fieldName, Map<String, String> fieldNameToFieldType, Account objAcc){
        if(fieldNameToFieldType.get(fieldName) == 'DATE'){
            objAcc.put(fieldName.trim(), Date.valueOf(fieldValue));
        }else if(fieldNameToFieldType.get(fieldName) == 'CURRENCY'){
            objAcc.put(fieldName.trim(), Decimal.valueOf(fieldValue));    
        }else {
            objAcc.put(fieldName.trim(), String.valueOf(fieldValue).trim());
        }
    }
}