public class TransactionManager : ITransactionManager
    {
        BankOfBIT_RIContext db = new BankOfBIT_RIContext();

        public void DoWork()
        {
        }

        public double? Deposit(int accountId, double amount, string notes)
        {
            double? total;

            try
            {
                total = Utility(accountId, amount, notes, (int)TransactionTypeValues.Deposit);
            }

            catch
            {
                total = null;
            }

            return total;
        }

       private double? Utility(int accountId, double amount, string notes, int type)
        {
            double? total;
                try
                {
                    //create bank account object using linq
                    BankAccount bankQuery = (from bank in db.BankAccounts
                                             where bank.BankAccountId == accountId
                                             select bank).SingleOrDefault();
                    bankQuery.Balance += amount;
                    bankQuery.ChangeState();
                    db.SaveChanges();

                CreateTransaction(accountId, amount, notes, type);

                    total =  bankQuery.Balance;
                }

                catch
                {
                    total = null;
                }
                return total;
        }

        private void CreateTransaction(int accountId, double amount, string notes, int type)
        {
            //make an if based on type just to modify the deposits and withdrawals
            Transaction trans;
            if (type == (int)TransactionTypeValues.Deposit || type == (int)TransactionTypeValues.TransferRecipient)
            {
                trans = new Transaction
                {
                    BankAccountId = accountId,
                    TransactionTypeId = type,
                    Deposit = amount,
                    Withdrawal = 0,
                    DateCreated = DateTime.Now,
                    Notes = notes
                };
                trans.SetNextTransactionNumber();
            }

            else
            {
                trans = new Transaction
                {
                    BankAccountId = accountId,
                    TransactionTypeId = type,
                    Deposit = amount,
                    Withdrawal = 0,
                    DateCreated = DateTime.Now,
                    Notes = notes
                };
            }

            db.Transactions.Add(trans);
            db.SaveChanges();
        }

        public double? Withdrawal(int accountId, double amount, string notes)
        {
            double? total;

            try
            {
                total = Utility(accountId, -amount, notes, (int)TransactionTypeValues.Withdrawal);
            }

            catch
            {
                total = null;
            }

            return total;
        }

        public double? BillPayment(int accountId, double amount, string notes)
        {
            return Utility(accountId, amount, notes, (int)TransactionTypeValues.BillPayment);
        }

        public double? Transfer(int fromAccountId, int toAccountId, double amount, string notes)
        {
            double? total;
            try
            {
                total = Utility(fromAccountId, -amount, notes, (int)TransactionTypeValues.Transfer);
                Utility(toAccountId, amount, notes, (int)TransactionTypeValues.Transfer);
            }

            catch
            {
                total = null;
            }

            return total;
        }

        public double? CalculateInterest(int accountId, string notes)
        {
            return 0;
        }

    }