public async ValueTask GenerateAuthTokenFromCredentialsProvider()

in src/AWSMSKAuthTokenGenerator.cs [237:288]
39 lines of code
6 McCabe index (conditional complexity)

    public async ValueTask<(string, long)> GenerateAuthTokenFromCredentialsProvider(Func<AWSCredentials> credentialsProvider, RegionEndpoint region, bool useAsync = true)
    {
        if (credentialsProvider == null)
        {
            throw new ArgumentNullException(nameof(credentialsProvider));
        }

        if (region == null)
        {
            throw new ArgumentNullException(nameof(region));
        }

        AWSCredentials credentials = credentialsProvider.Invoke();

        if (credentials == null)
        {
            throw new ArgumentNullException(nameof(credentials));
        }

        var immutableCredentials = useAsync ? await credentials.GetCredentialsAsync() : credentials.GetCredentials();

        _logger.LogDebug("Generating auth token using credentials with access key id: {accessKey}", immutableCredentials.AccessKey);

        var authTokenRequest = new GenerateMSKAuthTokenRequest();
        IRequest request = new DefaultRequest(authTokenRequest, ServiceName);

        request.UseQueryString = true;
        request.HttpMethod = HTTPMethod;
        request.Parameters.Add(XAmzExpires, ExpiryDuration.TotalSeconds.ToString(CultureInfo.InvariantCulture));
        request.Parameters.Add(ActionKey, ActionValue);
        var hostName = string.Format(HostnameStringFormat, region.SystemName);
        request.Endpoint = new UriBuilder(Scheme, hostName).Uri;

        if (immutableCredentials.UseToken)
        {
            request.Parameters[XAmzSecurityToken] = immutableCredentials.Token;
        }

        var signingResult = AWS4PreSignedUrlSigner.SignRequest(request, null, new RequestMetrics(),
            immutableCredentials.AccessKey,
            immutableCredentials.SecretKey, ServiceName, region.SystemName);

        var authorization = signingResult.ForQueryParameters;
        var url = AmazonServiceClient.ComposeUrl(request);

        var authTokenString = $"{url.AbsoluteUri}&{GetUserAgent()}&{authorization}";

        var byteArray = System.Text.Encoding.UTF8.GetBytes(authTokenString);

        var expiryMs = new DateTimeOffset(signingResult.DateTime.Add(ExpiryDuration)).ToUnixTimeSeconds() * 1000;
        return (Convert.ToBase64String(byteArray).Replace('+', '-').Replace('/', '_').TrimEnd('='), expiryMs);
    }