/// <summary>
/// Processes a payment after validating few cases. CHECKS FOR INNVALID CREDIT CARD AND VALID DATE ARE DONE
/// AT THE CONTROLLER/DTO LEVEL.
/// </summary>
/// <param name="payment">The payment to be processed</param>
/// <returns>A task that resolves to a string.</returns>
public async Task <string> ProcessAsync(PaymentDto payment)
{
if (payment == null)
{
throw new ArgumentNullException(nameof(payment));
}
if (payment.Amount <= 0)
{
throw new ArgumentException($"£{nameof(payment.Amount)} is not a valid amount");
}
if (payment.Amount >= 20 && payment.Amount < 21)
{
throw new Exception($"Cannot process payment between £20.01 to £20.99");
}
PaymentState paymentState = null;
string result = "";
try
{
//Insert into Payment Entity
var newPayment = _mapper.Map <Payment>(payment);
await _paymentRepo.InsertAsync(newPayment);
paymentState = new PaymentState
{
PaymentId = newPayment.Id,
State = nameof(PaymentStateEnum.PENDING)
};
await _paymentStateRepo.InsertAsync(paymentState);
//proceed to process payment...
if (payment.Amount < 20)
{
//use ICheapPaymentGateway to process the payment.
result = _cheapPaymentGateway.Process(payment);
}
else if (payment.Amount >= 21 && payment.Amount <= 500)
{
//use IExpensivePaymentGateway to process the payment.
result = await _expensivePaymentGateway.ProcessAsync(payment);
}
else
{
//use IPremiumPaymentGateway to process the payment.
result = await _premiumPaymentGateway.ProcessAsync(payment);
}
return(result);
}
finally
{
//paymentState could be null if the repository method never runs or
//it threw an unexpected exception.
//if that's the case, no need for cleanup.
if (paymentState != null)
{
if (result.Length > 1)
{
//there was no error
//update Payment State Entity to processed.
paymentState.State = nameof(PaymentStateEnum.PROCESSESD);
}
else
{
// update Payment State Entity
paymentState.State = nameof(PaymentStateEnum.FAILED);
}
await _paymentStateRepo.UpdateAsync(paymentState);
}
}
}