CleanMoneyTransferService

CleanMoneyTransferService

class FundTransferTxn
{
	private Account sourceAccount; 
	private Account targetAccount;
	private BigDecimal amount;
	private boolean allowDuplicateTxn;
	//setters & getters
}

public class CleanMoneyTransferService 
{
	public void transferFunds(FundTransferTxn txn) {
		Account sourceAccount = validateAndGetAccount(txn.getSourceAccount().getAcno());
		Account targetAccount = validateAndGetAccount(txn.getTargetAccount().getAcno());
		checkForOverdraft(sourceAccount, txn.getAmount());
		checkForDuplicateTransaction(txn);
		makeTransfer(sourceAccount, targetAccount, txn.getAmount());
	}
	
	private Account validateAndGetAccount(String acno){
		Account account = AccountDAO.getAccount(acno);
		if(account == null){
			throw new InvalidAccountException("Invalid ACNO :"+acno);
		}
		return account;
	}
	
	private void checkForOverdraft(Account account, BigDecimal amount){
		if(!account.isOverdraftAllowed()){
			if((account.getBalance() - amount) < 0)	{
				throw new InsufficientBalanceException("Insufficient Balance");
			}
		}
		else{
			if(((account.getBalance()+account.getOverdraftLimit()) - amount) < 0){
				throw new ExceedingOverdraftLimitException("Insufficient Balance, Exceeding Overdraft Limit");
			}
		}
	}
	
	private void checkForDuplicateTransaction(FundTransferTxn txn){
		AccountTransaction lastTxn = TransactionDAO.getLastTransaction(txn.getSourceAccount().getAcno());
		if(lastTxn != null)	{
			if(lastTxn.getTargetAcno().equals(txn.getTargetAccount().getAcno()) 
					&& lastTxn.getAmount() == txn.getAmount() 
					&& !txn.isAllowDuplicateTxn())	{
				throw new DuplicateTransactionException("Duplicate transaction exception");
			}
		}
	}
	
	private void makeTransfer(Account source, Account target, BigDecimal amount){
		sourceAccount.debit(amount);
		targetAccount.credit(amount);
		TransactionService.saveTransaction(source, target,  amount);
	}	
}