dependency-injection-based-on-request-headers.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers();
    services.AddHttpContextAccessor();

    services.AddTransient<DefaultMessageService>();

    services.AddTransient<ISecretKey, SecretKey>();
    services.AddTransient<HiddenMessageService>();

    services.AddScoped<IMessageService>(provider =>
    {
        var context = provider.GetRequiredService<IHttpContextAccessor>();
        var isHidden = context.HttpContext?.Request.Cookies.ContainsKey("hidden") == true;

        if (isHidden)
        {
            return provider.GetRequiredService<HiddenMessageService>();
        }

        return provider.GetRequiredService<DefaultMessageService>();
    });
}