CurrentUserService.cs

public class CurrentUserService : ICurrentUserService
{
    private readonly IHttpContextAccessor httpContextAccessor;

    public CurrentUserService(IHttpContextAccessor httpContextAccessor)
    {
        this.httpContextAccessor = httpContextAccessor ?? throw new ArgumentNullException(nameof(httpContextAccessor));
    }

    public string GetCurrentUsername()
    {
        return httpContextAccessor.HttpContext.User.Identity.Name;
    }
}