public IPaymentType Get(PaymentScheme paymentScheme)
{
IPaymentType paymentType = this._paymentTypes.FirstOrDefault(p => p.Type == paymentScheme);
Guard.AgainstNull(paymentType, $"PaymentType for Scheme {paymentScheme.ToString()} is not registered.");
return(paymentType);
}
protected void ValidatePaymentType(PaymentScheme scheme)
{
//To my knowledge this rule applies to all types of payments. Therefore it belongs here because in the spirit of
//DDD and DRY it's part of the validation of the Account domain entity.
//Another approach is to implement all the rules in a separate service e.g. IPaymentValidationService that is injected in Payment Service.
//I didn't do that because logically these checks are common for all payment schemes. In a real world scenario it
//would be clear from the bussiness requirements that it's beneficial to decouple the validation logic to separate
//classes per payment scheme.
if (!this.AllowedPaymentSchemes.HasFlag(scheme))
{
//normally there would be a custom exception like DomainArgumentException etc
throw new InvalidOperationException($"The account does not support {scheme.ToString()} payments.");
}
}