refactors data access layer to use pop ORM for eager loading, adds book titles rented to renters in response body

bookish-server/rental/rental.go

@@ -0,0 +1,65 @@
+package rental
+
+import (
+	"fmt"
+
+	"github.com/gofrs/uuid"
+)
+
+// Storage defines behavior for interacting with the inventory store.
+type Storage interface {
+	IsBookAvailable(title string) (available bool, err error)
+	RenterAlreadyCheckedOut(renterId uuid.UUID, title string) (checkedOut bool, err error)
+	CheckoutBook(renterId uuid.UUID, title string) error
+	ReturnBook(renterId uuid.UUID, title string) error
+}
+
+type service struct {
+	store Storage
+}
+
+// Service defines behavior for interacting with the inventory service.
+type Service interface {
+	IsBookAvailable(title string) (available bool, err error)
+	CheckoutBook(renterId uuid.UUID, title string) error
+	ReturnBook(renterId uuid.UUID, title string) error
+}
+
+// NewService creates a new inventory service.
+func NewService(s Storage) *service {
+	return &service{
+		s,
+	}
+}
+
+// IsBookAvailable checks if a book is available to rent at this library.
+func (s *service) IsBookAvailable(title string) (available bool, err error) {
+	return s.store.IsBookAvailable(title)
+}
+
+// CheckoutBook checks a book out to a renter.
+func (s *service) CheckoutBook(renterId uuid.UUID, title string) error {
+	available, err := s.IsBookAvailable(title)
+	if err != nil {
+		return err
+	}
+
+	if !available {
+		return ErrUnavailableBook
+	}
+
+	checkedOut, err := s.store.RenterAlreadyCheckedOut(renterId, title)
+	// If there was an error or the book is checked out by the renter already we'll
+	// say the book is unavailable.
+	if err != nil || checkedOut {
+		fmt.Println("unavailable book", err, checkedOut)
+		return ErrUnavailableBook
+	}
+
+	return s.store.CheckoutBook(renterId, title)
+}
+
+// ReturnBook returns a book for a renter.
+func (s *service) ReturnBook(renterId uuid.UUID, title string) error {
+	return s.store.ReturnBook(renterId, title)
+}