public Loan LoanABook(long memberId, long bookId)
{
using (ILoanUnitOfWork uow = _uowFactory.GetLoanUnitOfWork())
{
Book bookToLoan = uow.FindBook(bookId);
if (bookToLoan == null)
{
throw new InvalidOperationException("The book does not exist.");
}
if (bookToLoan.Status == BookStatus.OnLoan)
{
throw new InvalidOperationException("The book is already on loan.");
}
if (HasMemberBorrowedMaxNumberOfBooks(uow, memberId))
{
throw new InvalidOperationException("You have borrowed the maximum number of books allowed.");
}
Loan newLoan = CreateNewLoanRecord(uow, memberId, bookToLoan.BookId);
bookToLoan.Status = BookStatus.OnLoan;
uow.Save();
return(newLoan);
}
}
public IEnumerable <Book> GetBooks(string title)
{
using (ILoanUnitOfWork uow = _uowFactory.GetLoanUnitOfWork())
{
return(uow.GetBooks(b => b.Title == title));
}
}
private Loan CreateNewLoanRecord(ILoanUnitOfWork uow, long memberId, long bookId)
{
var newLoan = new Loan
{
MemberId = memberId,
BookId = bookId,
Status = LoanStatus.Open,
LoanDate = DateTime.UtcNow.Date,
ExpectedReturnDate = DateTime.UtcNow.Date.AddDays(LoanDuration)
};
uow.InsertLoanRecord(newLoan);
return(newLoan);
}
private bool HasMemberBorrowedMaxNumberOfBooks(ILoanUnitOfWork uow, long memberId)
{
int numberOfBooksOnLoan = uow.GetLoans(loan => loan.MemberId == memberId && loan.Status == LoanStatus.Open).Count();
return(numberOfBooksOnLoan == MaxNumberOfBook);
}