Task: Events are received from users, each needs to be verified in an external source, but it does not respond immediately.
Implement VerificationService which:
- Accepts events from users
- Tries to verify each by contacting an external service
- If the response is PENDING, retries sending this event no earlier than 5 seconds later
- Maximum 3 attempts, after which the event ID is output to stdout with status FAILED
- Successfully processed events are output to stdout with status VERIFIED
The templates and stubs of external dependencies are already implemented:
1. VerificationStatus
2. Event
3. VerificationResult
4. IExternalSource
public enum VerificationStatus { OK, Pending, Error }
public record Event(string Id, string Payload);
public record VerificationResult(VerificationStatus Status, string? Message = null);
public interface IExternalSource
{
VerificationResult Verify(string eventId);
}
public class VerificationService
{
private readonly IExternalSource _externalSource;
private const int MaxAttempts = 3;
private static readonly TimeSpan RetryDelay = TimeSpan.FromSeconds(5);
public VerificationService(IExternalSource externalSource)
{
_externalSource = externalSource;
}
// TODO: implement
}
