public async Task <IActionResult> Post(BookDto book)
{
if (!await _subscriptionsService.DoesBookExists(book.BookId))
{
return(BadRequest("Book subscription doesn't exist"));
}
if (await _subscriptionsService.IsSubscriptionAlreadyPurchased(book.BookId))
{
return(BadRequest("Book subscription is already purchased"));
}
var result = await _subscriptionsService.PurchaseSubscription(book);
return(Ok(result));
}