public async Task AttachFileToIssue()

in src/YouTrackSharp/Issues/IssuesService.Attachments.cs [15:81]
62 lines of code
10 McCabe index (conditional complexity)

        public async Task AttachFileToIssue(string issueId, string attachmentName, Stream attachmentStream, string group = null, string author = null, string attachmentContentType = null)
        {
            if (string.IsNullOrEmpty(issueId))
            {
                throw new ArgumentNullException(nameof(issueId));
            }
            if (string.IsNullOrEmpty(attachmentName))
            {
                throw new ArgumentNullException(nameof(attachmentName));
            }
            if (attachmentStream == null)
            {
                throw new ArgumentNullException(nameof(attachmentStream));
            }
            
            var client = await _connection.GetAuthenticatedApiClient();

            var attachment = new IssueAttachment();
            if (!string.IsNullOrEmpty(attachmentName))
            {
                attachment.Name = attachmentName;
            }
            if (!string.IsNullOrEmpty(group))
            {
                var visibilityGroups = await client.VisibilitygroupsAsync(
                    "groupsWithoutRecommended(id,name),recommendedGroups(id,name)", 0, -1,
                    new VisibilityGroupsRequest()
                    {
                        Prefix = group.ToLower(),
                        Top = 1000000000,
                        Issues = new List<Generated.Issue>() {new Generated.Issue() {IdReadable = issueId}}
                    });
                var userGroup =
                    visibilityGroups.RecommendedGroups.FirstOrDefault(g =>
                        g.Name.Equals(group, StringComparison.InvariantCultureIgnoreCase)) ??
                    visibilityGroups.GroupsWithoutRecommended.FirstOrDefault(g =>
                        g.Name.Equals(group, StringComparison.InvariantCultureIgnoreCase));
                if (userGroup == null)
                {
                    throw new YouTrackErrorException(Strings.Exception_BadRequest, (int)HttpStatusCode.BadRequest,
                        $"Could not suggest visibility group with name {group} for issue {issueId}",
                        null, null);
                }
                attachment.Visibility = new LimitedVisibility() {PermittedGroups = new List<UserGroup> {userGroup}};
            }
            if (!string.IsNullOrEmpty(author))
            {
                attachment.Author = new Me() {Login = author};
            }
            if (!string.IsNullOrEmpty(attachmentContentType))
            {
                attachment.MimeType = attachmentContentType;
            }
            
            var response = await client.IssuesAttachmentsPostAsync(issueId, false, "id",
                new FileParameter(attachmentStream, attachmentName, attachmentContentType));

            var apiAttachment = response.FirstOrDefault();
            if (apiAttachment == null)
            {
                throw new YouTrackErrorException(Strings.Exception_BadRequest, (int)HttpStatusCode.OK,
                    $"Failed to upload attachment: server returned HTTP OK with empty response",
                    null, null);
            }
            
            await client.IssuesAttachmentsPostAsync(issueId, apiAttachment.Id, "id", attachment);
        }