Nancy pipeline handler for content negotiation

ContentNegotiationPipelineItem.cs

    public class ContentNegotiationPipelineItem : PipelineItem<Action<NancyContext>>
    {

        public ContentNegotiationPipelineItem()
            : base("Content Negotiation", action)
        {
        }

        static readonly Action<NancyContext> action = ctx =>
        {
            var request = ctx.Request;
            if (request == null || request.Headers == null || request.Headers.Accept == null)
                return;

            if (!ctx.Items.ContainsKey("Content-Negotiation")) return;
           
            var responses = (List<Response>)ctx.Items["Content-Negotiation"];
            if (responses == null) return;
            responses.Insert(0, new Response
            {
                Contents = ctx.Response.Contents,
                ContentType = ctx.Response.ContentType,
                Headers = ctx.Response.Headers,
                StatusCode = ctx.Response.StatusCode
            });
            foreach (var cookie in ctx.Response.Cookies)
                responses[0].AddCookie(cookie);

            foreach (var contentType in request.Headers.Accept.Select(x => x.Item1))
            {
                var indexOf = contentType.IndexOf("/", StringComparison.Ordinal);
                if (contentType == "*/*")
                    return;

                var response = contentType.EndsWith("/*")
                                   ? responses.FirstOrDefault(
                                       x => x.ContentType.StartsWith(contentType.Substring(0, indexOf)))
                                   : responses.FirstOrDefault(x => x.ContentType == contentType);

                if (response != null)
                {
                    ctx.Response = response;
                    break;
                }
            }
        };

    }