CustomPageRouteHandler - inherit from Feather

namespace SitefinityWebApp.Websilk
{
    public class CustomPageRouteHandler : MvcPageRouteHandler
    {
        protected override bool ApplyServerCache(HttpContextBase context, OutputCacheProfileElement profile, PageSiteNode siteNode)
        {
            var allowCaching = false;

            //Never cache POST requests, and never cache if the USER isn't null
            if (context.Request.RequestType != "POST" && !ClaimsManager.GetCurrentIdentity().IsAuthenticated)
            {
                //NB: this always returns true, but maybe that changes in future?
                allowCaching = base.ApplyServerCache(context, profile, siteNode);

                //Need to use reflection as .NET does not allow for setting false value once we've set it to true
                var headers = context.Response.Cache.VaryByHeaders;
                var headersCollection = headers.GetType().GetField("_headers", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(headers) as NameObjectCollectionBase;

                if (headersCollection != null)
                {
                    var method = headersCollection.GetType().GetMethod("BaseRemove", BindingFlags.NonPublic | BindingFlags.Instance);
                    method.Invoke(headersCollection, new object[] { "User-Agent" });
                }

                //Extra cache callback check... It should never return cached item for logged in users
                context.Response.Cache.AddValidationCallback(IgnoreCacheRequestIfLoggedIn, null);
            }
            else
            {
                //Never cache POST or Authenticated requests
                context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
            }

            return allowCaching;
        }

        static void IgnoreCacheRequestIfLoggedIn(HttpContext context, object data, ref HttpValidationStatus status)
        {
            //Ignore cache for logged in users, but everyone else is still valid
            //NB: There's much extra logic in the base Sitefinity PageRouteHandler
            status = ClaimsManager.GetCurrentIdentity().IsAuthenticated ? HttpValidationStatus.IgnoreThisRequest : status;
        }
    }
}