added transaction in registration

internal/service/users/user_service.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"errors"
 
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
 	"go.uber.org/zap"
 
 	"git.kanopo.dev/rhythm/rhythm-backend/internal/config"
@@ -26,16 +28,18 @@ type Service interface {
 }
 
 type service struct {
+	pool *pgxpool.Pool
 	repo usersdb.Querier
 	cfg  *config.Config
 	log  *zap.SugaredLogger
 }
 
-func NewService(repo usersdb.Querier, cfg *config.Config, log *zap.SugaredLogger) Service {
+func NewService(repo usersdb.Querier, cfg *config.Config, log *zap.SugaredLogger, pool *pgxpool.Pool) Service {
 	return &service{
 		repo: repo,
 		cfg:  cfg,
 		log:  log,
+		pool: pool,
 	}
 }
 
@@ -66,18 +70,29 @@ func (s *service) Login(ctx context.Context, email, passwordPlain string) (*Auth
 }
 
 func (s *service) Register(ctx context.Context, email, passwordPlain string) (*AuthResult, error) {
-	_, err := s.repo.GetUserByEmail(ctx, email)
+	tx, err := s.pool.BeginTx(ctx, pgx.TxOptions{})
+	if err != nil {
+		return nil, err
+	}
+	defer tx.Rollback(ctx)
+
+	txRepo := usersdb.New(tx)
+
+	_, err = txRepo.GetUserByEmail(ctx, email)
 	if err == nil {
 		s.log.Infof("registration failed: email already exists %v", email)
 		return nil, ErrInvalidCredentials
 	}
+	if !errors.Is(err, pgx.ErrNoRows) {
+		return nil, err
+	}
 
 	hash, err := password.HashPassword(passwordPlain)
 	if err != nil {
 		return nil, err
 	}
 
-	user, err := s.repo.CreateUser(ctx, usersdb.CreateUserParams{
+	user, err := txRepo.CreateUser(ctx, usersdb.CreateUserParams{
 		Email:    email,
 		Password: hash,
 	})
@@ -85,6 +100,10 @@ func (s *service) Register(ctx context.Context, email, passwordPlain string) (*A
 		return nil, err
 	}
 
+	if err := tx.Commit(ctx); err != nil {
+		return nil, err
+	}
+
 	tokenPair, err := jwt.GenerateTokenPair(user.ID.String(), s.cfg)
 	if err != nil {
 		s.log.Error("failed to generate token pair", "error", err)