public async Task <IActionResult> Details(int id)
        {
            var presentation = await _presentationRepository.GetPresentationByIdAsync(id);

            var user    = HttpContext.User.Identity.Name;
            var speaker = await _speakerRepository.GetSpeakerBySpeakerEmailIncludingRelationshipsAsync(user);

            if (!(speaker.OwnedPresentations.Contains(presentation)))
            {
                return(Forbid());
            }

            var presentationViewModel = _presentationViewModelMapper.MapPresentationToPresentationViewModel(presentation);

            return(View(presentationViewModel));
        }