A better load balancer HTTPS redirect

Startup.Security.cs

using Owin;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace Whatevs
{
    public partial class Startup
    {
        private IAppBuilder UseSecurityChecks(IAppBuilder app)
        {
            app.Use((context, next) =>
            {
                string[] proto;
                if (context.Request.Headers.TryGetValue("X-Forwarded-Proto", out proto) && proto.FirstOrDefault() == "http")
                {
                    context.Response.StatusCode = 301;
                    context.Response.Headers["Location"] = Regex.Replace(context.Request.Uri.ToString(), "^https|^http", "https");
                    return Task.CompletedTask;
                }
                else
                {
                    return next();
                }
            });

            return app;
        }
    }
}

You may be wondering "why are we replacing http or https for the location?" The reason is that the load balancer itself might be connecting to the web server via https (not uncommon and is set up this way in our environment). In this case the web server might put https for the scheme even though the client connected insecurely to the load balancer.