public override Task ProcessHttpRequestAsync()

in sdk/batch/Microsoft.Azure.Batch/src/Protocol/BatchSharedKeyCredential.cs [59:168]
90 lines of code
31 McCabe index (conditional complexity)

        public override Task ProcessHttpRequestAsync(HttpRequestMessage httpRequest, CancellationToken cancellationToken)
        {
            if (httpRequest == null)
            {
                return Async.CompletedTask;
            }

            //First set ocp-date always
            if (!httpRequest.Headers.Contains(OCPDateHeaderString))
            {
                httpRequest.Headers.TryAddWithoutValidation(OCPDateHeaderString, string.Format(CultureInfo.InvariantCulture, "{0:R}", DateTime.UtcNow));
            }

            // Set Headers
            var signature = new StringBuilder();
            signature.Append(httpRequest.Method).Append('\n');
            signature.Append(httpRequest.Content != null && httpRequest.Content.Headers.Contains("Content-Encoding") ? httpRequest.Content.Headers.GetValues("Content-Encoding").FirstOrDefault() : string.Empty).Append('\n');
            signature.Append(httpRequest.Content != null && httpRequest.Content.Headers.Contains("Content-Language") ? httpRequest.Content.Headers.GetValues("Content-Language").FirstOrDefault() : string.Empty).Append('\n');

            // Handle content length
            long? contentLength = httpRequest.Content?.Headers?.ContentLength;

            if (contentLength == null)
            {
                // C# in .NET Framework adds a content-lenth = 0 reader for DELETE, PATH, OPTIONS, and POST, so we need to manually set the content-length to 0
                // Because of https://github.com/dotnet/corefx/issues/31172 netstandard/netcore has different behavior depending on version, so we purpusefully set 
                // httoRequest.Content to an empty array to froce inclusion of content-length = 0 on all versions.
                if (httpRequest.Method == HttpMethod.Delete || httpRequest.Method == new HttpMethod("PATCH") || httpRequest.Method == HttpMethod.Options || httpRequest.Method == HttpMethod.Post)
                {
                    httpRequest.Content = new ByteArrayContent(EmptyArray);
                    contentLength = 0;
                }
            }
            signature.Append(contentLength).Append('\n');

            signature.Append(httpRequest.Content != null && httpRequest.Content.Headers.Contains("Content-MD5") ? httpRequest.Content.Headers.GetValues("Content-MD5").FirstOrDefault() : string.Empty).Append('\n');
            signature.Append(httpRequest.Content != null && httpRequest.Content.Headers.Contains("Content-Type") ? httpRequest.Content.Headers.GetValues("Content-Type").FirstOrDefault() : string.Empty).Append('\n');
            signature.Append(httpRequest.Headers.Contains("Date") ? httpRequest.Headers.GetValues("Date").FirstOrDefault() : string.Empty).Append('\n');
            signature.Append(httpRequest.Headers.Contains("If-Modified-Since") ? httpRequest.Headers.GetValues("If-Modified-Since").FirstOrDefault() : string.Empty).Append('\n');
            signature.Append(httpRequest.Headers.Contains("If-Match") ? httpRequest.Headers.GetValues("If-Match").FirstOrDefault() : string.Empty).Append('\n');
            signature.Append(httpRequest.Headers.Contains("If-None-Match") ? httpRequest.Headers.GetValues("If-None-Match").FirstOrDefault() : string.Empty).Append('\n');
            signature.Append(httpRequest.Headers.Contains("If-Unmodified-Since") ? httpRequest.Headers.GetValues("If-Unmodified-Since").FirstOrDefault() : string.Empty).Append('\n');
            signature.Append(httpRequest.Headers.Contains("Range") ? httpRequest.Headers.GetValues("Range").FirstOrDefault() : string.Empty).Append('\n');

            List<string> customHeaders = new List<string>();
            foreach (KeyValuePair<string, IEnumerable<string>> header in httpRequest.Headers)
            {
                if (header.Key.StartsWith("ocp-", StringComparison.OrdinalIgnoreCase))
                {
                    customHeaders.Add(header.Key.ToLowerInvariant());
                }
            }

            if (httpRequest.Content != null)
            {
                foreach (KeyValuePair<string, IEnumerable<string>> contentHeader in httpRequest.Content.Headers)
                {
                    if (contentHeader.Key.StartsWith("ocp-", StringComparison.OrdinalIgnoreCase))
                    {
                        customHeaders.Add(contentHeader.Key.ToLowerInvariant());
                    }
                }
            }
            customHeaders.Sort(StringComparer.Ordinal);

            foreach (string canonicalHeader in customHeaders)
            {
                string value = httpRequest.Headers.GetValues(canonicalHeader).FirstOrDefault();
                value = value.Replace('\n', ' ').Replace('\r', ' ').TrimStart();
                signature.Append(canonicalHeader).Append(':').Append(value).Append('\n');
            }

            signature.Append('/').Append(AccountName).Append('/').Append(httpRequest.RequestUri.AbsolutePath.TrimStart('/'));
            if (!string.IsNullOrEmpty(httpRequest.RequestUri.Query))
            {
#if FullNetFx
                NameValueCollection queryVariables = System.Web.HttpUtility.ParseQueryString(httpRequest.RequestUri.Query);
                List<string> queryVariableKeys = new List<string>(queryVariables.AllKeys);
#else
                Dictionary<string, Extensions.Primitives.StringValues> queryVariables = Microsoft.AspNetCore.WebUtilities.QueryHelpers.ParseQuery(httpRequest.RequestUri.Query);
                List<string> queryVariableKeys = new List<string>(queryVariables.Keys);
#endif

                queryVariableKeys.Sort(StringComparer.OrdinalIgnoreCase);

                foreach (string queryKey in queryVariableKeys)
                {
                    string lowercaseQueryKey;
                    if (queryKey != null)
                    {
                        lowercaseQueryKey = queryKey.ToLowerInvariant();
                    }
                    else
                    {
                        lowercaseQueryKey = null;
                    }
                    signature.Append('\n').Append(lowercaseQueryKey).Append(':').Append(queryVariables[queryKey]);
                }
            }

            string signedSignature = null;

            using (HashAlgorithm hashAlgorithm = new HMACSHA256(Convert.FromBase64String(this.KeyValue)))
            {
                signedSignature = Convert.ToBase64String(hashAlgorithm.ComputeHash(Encoding.UTF8.GetBytes(signature.ToString())));
            }
            httpRequest.Headers.Authorization = new AuthenticationHeaderValue("SharedKey", this.AccountName + ":" + signedSignature);

            return Async.CompletedTask;
        }