public class Startup
{
    public Startup(IConfiguration configuration, IWebHostEnvironment env)
    {
        Configuration = configuration;
        Env = env;

        var builder = new ConfigurationBuilder()
            .SetBasePath(Environment.CurrentDirectory)
            .AddJsonFile("appsettings.json", optional: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);

        if (env.IsDevelopment())
            builder.AddUserSecrets<Startup>();

        Configuration = builder.Build();
    }

    public IConfiguration Configuration { get; }
    public IWebHostEnvironment Env { get; }
    public static RequestCulture DefaultRequestCulture = new RequestCulture("en-US", "en-US");

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddOptions();
        services.AddSingleton(Configuration);

        services.AddRazorPages(options =>
        {
            options.Conventions.Add(new CultureTemplateRouteModelConvention());
        }).SetCompatibilityVersion(CompatibilityVersion.Version_3_0);

        services.AddLocalization(options => options.ResourcesPath = "Resources");

        services.Configure<RequestLocalizationOptions>(options =>
        {
            options.DefaultRequestCulture = DefaultRequestCulture;
            options.SupportedCultures = AppConstants.SupportedCultures;
            options.SupportedUICultures = AppConstants.SupportedCultures;

            options.RequestCultureProviders.Insert(0, new RouteDataRequestCultureProvider { Options = options });
        });

        services.AddRouting(options =>
        {
            options.LowercaseUrls = true;
        });

        services.AddOptions();
        services.AddLogging();
        services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
        services.AddSingleton(Configuration);
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        Container = app.ApplicationServices.GetAutofacRoot();

        app.UseStaticFiles();
        app.UseRouting();
        app.UseRequestLocalization();
        app.UseAuthorization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapRazorPages();
    }
}

public class CultureTemplateRouteModelConvention : IPageRouteModelConvention
{
    public void Apply(PageRouteModel model)
    {
        var selectorCount = model.Selectors.Count;

        for (var i = 0; i < selectorCount; i++)
        {
            var selector = model.Selectors[i];

            model.Selectors.Add(new SelectorModel
            {
                AttributeRouteModel = new AttributeRouteModel
                {
                    Order = -1,
                    Template = AttributeRouteModel.CombineTemplates(
                          "{culture?}", selector.AttributeRouteModel.Template),
                }
            });
        }
    }
}