public static MessageView FromProtobuf()

in csharp/rocketmq-client-csharp/MessageView.cs [92:197]
96 lines of code
19 McCabe index (conditional complexity)

        public static MessageView FromProtobuf(Proto.Message message, MessageQueue messageQueue = null)
        {
            var topic = message.Topic.Name;
            var systemProperties = message.SystemProperties;
            var messageId = systemProperties.MessageId;
            var bodyDigest = systemProperties.BodyDigest;
            var checkSum = bodyDigest.Checksum;
            var raw = message.Body.ToByteArray();
            var corrupted = false;
            var type = bodyDigest.Type;
            switch (type)
            {
                case Proto.DigestType.Crc32:
                    {
                        var expectedCheckSum = Force.Crc32.Crc32Algorithm.Compute(raw, 0, raw.Length).ToString("X");
                        if (!expectedCheckSum.Equals(checkSum))
                        {
                            corrupted = true;
                        }

                        break;
                    }
                case Proto.DigestType.Md5:
                    {
                        var expectedCheckSum = Utilities.ComputeMd5Hash(raw);
                        if (!expectedCheckSum.Equals(checkSum))
                        {
                            corrupted = true;
                        }

                        break;
                    }
                case Proto.DigestType.Sha1:
                    {
                        var expectedCheckSum = Utilities.ComputeSha1Hash(raw);
                        if (!expectedCheckSum.Equals(checkSum))
                        {
                            corrupted = true;
                        }

                        break;
                    }
                case Proto.DigestType.Unspecified:
                default:
                    {
                        Logger.LogError(
                            $"Unsupported message body digest algorithm," +
                            $"digestType={type}, topic={topic}, messageId={messageId}");
                        break;
                    }
            }

            var bodyEncoding = systemProperties.BodyEncoding;
            var body = raw;
            switch (bodyEncoding)
            {
                case Proto.Encoding.Gzip:
                    {
                        // Gzip
                        if (body[0] == 0x1f && body[1] == 0x8b)
                        {
                            body = Utilities.DecompressBytesGzip(raw);
                        }
                        // Zlib
                        else if (body[0] == 0x78 || body[0] == 0x79)
                        {
                            body = Utilities.DecompressBytesZlib(raw);
                        }
                        break;
                    }
                case Proto.Encoding.Identity:
                    {
                        break;
                    }
                case Proto.Encoding.Unspecified:
                default:
                    {
                        Logger.LogError($"Unsupported message encoding algorithm," +
                                        $" topic={topic}, messageId={messageId}, bodyEncoding={bodyEncoding}");
                        break;
                    }
            }

            var tag = systemProperties.HasTag ? systemProperties.Tag : null;
            var messageGroup = systemProperties.HasMessageGroup ? systemProperties.MessageGroup : null;
            DateTime? deliveryTime = null == systemProperties.DeliveryTimestamp
                ? null
                : (DateTime?)TimeZoneInfo.ConvertTimeFromUtc(systemProperties.DeliveryTimestamp.ToDateTime(), TimeZoneInfo.Local);
            var keys = systemProperties.Keys.ToList();

            var bornHost = systemProperties.BornHost;
            var bornTime =
                TimeZoneInfo.ConvertTimeFromUtc(systemProperties.BornTimestamp.ToDateTime(), TimeZoneInfo.Local);
            var deliveryAttempt = systemProperties.DeliveryAttempt;
            var queueOffset = systemProperties.QueueOffset;
            var properties = new Dictionary<string, string>();
            foreach (var (key, value) in message.UserProperties)
            {
                properties.Add(key, value);
            }


            var receiptHandle = systemProperties.ReceiptHandle;
            return new MessageView(messageId, topic, body, tag, messageGroup, deliveryTime, keys, properties, bornHost,
                bornTime, deliveryAttempt, messageQueue, receiptHandle, queueOffset, corrupted);
        }