public override async Task ContinueDialogAsync()

in libraries/Microsoft.Bot.Builder.Dialogs/Prompts/OAuthPrompt.cs [465:530]
56 lines of code
19 McCabe index (conditional complexity)

        public override async Task<DialogTurnResult> ContinueDialogAsync(DialogContext dc, CancellationToken cancellationToken = default)
        {
            if (dc == null)
            {
                throw new ArgumentNullException(nameof(dc));
            }

            // Check for timeout
            var state = dc.ActiveDialog.State;
            var expires = (DateTime)state[PersistedExpires];
            var isMessage = dc.Context.Activity.Type == ActivityTypes.Message;

            // If the incoming Activity is a message, or an Activity Type normally handled by OAuthPrompt,
            // check to see if this OAuthPrompt Expiration has elapsed, and end the dialog if so.
            var isTimeoutActivityType = isMessage
                            || IsTokenResponseEvent(dc.Context)
                            || IsTeamsVerificationInvoke(dc.Context)
                            || IsTokenExchangeRequestInvoke(dc.Context);
            var hasTimedOut = isTimeoutActivityType && DateTime.Compare(DateTime.UtcNow, expires) > 0;

            if (hasTimedOut)
            {
                // if the token fetch request times out, complete the prompt with no result.
                return await dc.EndDialogAsync(cancellationToken: cancellationToken).ConfigureAwait(false);
            }

            // Recognize token
            var recognized = await RecognizeTokenAsync(_settings, dc, cancellationToken).ConfigureAwait(false);

            var promptState = state[PersistedState].CastTo<IDictionary<string, object>>();
            var promptOptions = state[PersistedOptions].CastTo<PromptOptions>();

            // Increment attempt count
            // Convert.ToInt32 For issue https://github.com/Microsoft/botbuilder-dotnet/issues/1859
            promptState[Prompt<int>.AttemptCountKey] = Convert.ToInt32(promptState[Prompt<int>.AttemptCountKey], CultureInfo.InvariantCulture) + 1;

            // Validate the return value
            var isValid = false;
            if (_validator != null)
            {
                var promptContext = new PromptValidatorContext<TokenResponse>(dc.Context, recognized, promptState, promptOptions);
                isValid = await _validator(promptContext, cancellationToken).ConfigureAwait(false);
            }
            else if (recognized.Succeeded)
            {
                isValid = true;
            }

            // Return recognized value or re-prompt
            if (isValid)
            {
                return await dc.EndDialogAsync(recognized.Value, cancellationToken).ConfigureAwait(false);
            }
            else if (isMessage && _settings.EndOnInvalidMessage)
            {
                // If EndOnInvalidMessage is set, complete the prompt with no result.
                return await dc.EndDialogAsync(cancellationToken: cancellationToken).ConfigureAwait(false);
            }

            if (!dc.Context.Responded && isMessage && promptOptions?.RetryPrompt != null)
            {
                await dc.Context.SendActivityAsync(promptOptions.RetryPrompt, cancellationToken).ConfigureAwait(false);
            }

            return EndOfTurn;
        }