@inject NavigationManager Navigation
@inject AuthenticationStateProvider AuthStateProvider

@code {
    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (!firstRender)
        {
            return;
        }

        var authState = await AuthStateProvider.GetAuthenticationStateAsync();
        if (authState.User.Identity?.IsAuthenticated == true)
        {
            return;
        }

        var path = new Uri(Navigation.Uri).AbsolutePath;
        if (path.Equals("/login", StringComparison.OrdinalIgnoreCase))
        {
            return;
        }

        var returnUrl = Uri.EscapeDataString(path);
        Navigation.NavigateTo($"/login?ReturnUrl={returnUrl}", forceLoad: true);
    }
}