public class AccountController : Controller
{
    private Uri RedirectUri
    {
        get
        {
            var uriBuilder = new UriBuilder(Request.Url);
            uriBuilder.Query = null;
            uriBuilder.Fragment = null;
            uriBuilder.Path = Url.Action("FacebookCallback");
            return uriBuilder.Uri;
        }
    }

    public ActionResult Facebook()
    {
        var fb = new FacebookClient();
        var loginUrl = fb.GetLoginUrl(new {
            client_id = "your_app_id_here",
            redirect_uri = RedirectUri.AbsoluteUri,
            response_type = "code",
            scope = "email" // Add other permissions as needed
        });

        return Redirect(loginUrl.AbsoluteUri);
    }

}