59 lines
1.6 KiB
Go
59 lines
1.6 KiB
Go
package inventory
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// Storage defines behavior for interacting with the inventory store.
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type Storage interface {
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IsBookAvailable(title string) (available bool, err error)
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RenterAlreadyCheckedOut(renterId int, title string) (checkedOut bool, err error)
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CheckoutBook(renterId int, title string) error
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ReturnBook(renterId int, title string) error
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}
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type service struct {
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store Storage
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}
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// Service defines behavior for interacting with the inventory service.
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type Service interface {
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IsBookAvailable(title string) (available bool, err error)
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CheckoutBook(renterId int, title string) error
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ReturnBook(renterId int, title string) error
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}
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// NewService creates a new inventory service.
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func NewService(s Storage) *service {
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return &service{
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s,
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}
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}
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// IsBookAvailable checks if a book is available to rent at this library.
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func (s *service) IsBookAvailable(title string) (available bool, err error) {
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return s.store.IsBookAvailable(title)
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}
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// CheckoutBook checks a book out to a renter.
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func (s *service) CheckoutBook(renterId int, title string) error {
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available, err := s.IsBookAvailable(title)
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if err != nil {
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return err
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}
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if !available {
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return ErrUnavailableBook
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}
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checkedOut, err := s.store.RenterAlreadyCheckedOut(renterId, title)
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// If there was an error or the book is checked out by the renter already we'll
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// say the book is unavailable.
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if err != nil || checkedOut {
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return ErrUnavailableBook
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}
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return s.store.CheckoutBook(renterId, title)
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}
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// ReturnBook returns a book for a renter.
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func (s *service) ReturnBook(renterId int, title string) error {
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return s.store.ReturnBook(renterId, title)
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}
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