public async Task <ActionResult> GetLesson(long id)
{
var user = long.Parse(User.Claims.First().Value);
var lesson = await repository.GetLessonById(id);
var link = await storage.GetPreSignedLink(lesson.Link);
var metadata = await storage.GetObjectInfo(lesson.Link);
var result = mapper.Map <LessonDTO>(lesson);
result.Link = link ?? lesson.Link;
result.Size = metadata == null ? 0 : metadata.Size;
await repository.AddToHistory(user, id);
return(Ok(result));
}