user: add a service stub with validated register method

1 files changed, 56 insertions, 0 deletions

diff --git a/internal/user/service.go b/internal/user/service.go
new file mode 100644
index 0000000..a8a72a6
--- /dev/null
+++ b/internal/user/service.go
@@ -0,0 +1,56 @@
+package user
+
+import (
+	"errors"
+	"fmt"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+type Repository interface {
+	Create(in *CreateInput) (*User, error)
+	GetByUsernameOrEmail(username string, email string) (*User, error)
+}
+
+type Service struct {
+	repository Repository
+	bcryptCost int
+}
+
+func New(r Repository) *Service {
+	return &Service{repository: r, bcryptCost: bcrypt.DefaultCost}
+}
+
+func (s *Service) Register(in *RegisterInput) (*User, error) {
+	if err := in.validate(); err != nil {
+		return nil, fmt.Errorf("register: %w", err)
+	}
+
+	_, err := s.repository.GetByUsernameOrEmail(in.Username, in.Email)
+	if err == nil {
+		return nil, fmt.Errorf("register: %w", ErrUserExists)
+	}
+
+	if !errors.Is(err, ErrUserNotFound) {
+		return nil, fmt.Errorf("register: %w", err)
+	}
+
+	pwHash, err := bcrypt.GenerateFromPassword([]byte(in.Password), s.bcryptCost)
+	if err != nil {
+		return nil, fmt.Errorf("register: %w", err)
+	}
+
+	ci := &CreateInput{
+		Username: in.Username,
+		Email:    in.Email,
+		Phone:    in.Phone,
+		PwHash:   string(pwHash),
+	}
+
+	user, err := s.repository.Create(ci)
+	if err != nil {
+		return nil, fmt.Errorf("register: %w", err)
+	}
+
+	return user, nil
+}