Url Helper for ASP.NET MVC hosted on AppHarbor

UrlHelperExtensions.cs

public static string ToPublicUrl(this UrlHelper urlHelper, Uri relativeUri)
{
    var httpContext = urlHelper.RequestContext.HttpContext;

    var uriBuilder = new UriBuilder
    {
            Host = httpContext.Request.Url.Host,
            Path = "/",
            Port = 80,
            Scheme = "http",
    };

    if (httpContext.Request.IsLocal)
    {
        uriBuilder.Port = httpContext.Request.Url.Port;
    }

    return new Uri(uriBuilder.Uri, relativeUri).AbsoluteUri;
}