add users logic

users/internal/storage/postgres/user_repo.go

@@ -0,0 +1,85 @@
+package postgres
+
+import (
+	"context"
+	"errors"
+
+	sq "github.com/Masterminds/squirrel"
+	"github.com/google/uuid"
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgconn"
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"github.com/emil28092005/SciMesh/users/internal/domain"
+	"github.com/emil28092005/SciMesh/users/internal/usecase"
+)
+
+// uniqueViolation is PostgreSQL's SQLSTATE for a unique-constraint breach.
+const uniqueViolation = "23505"
+
+var userColumns = []string{"id", "email", "password_hash", "role", "created_at", "updated_at"}
+
+// UserRepo implements usecase.UserRepository on PostgreSQL.
+type UserRepo struct {
+	pool *pgxpool.Pool
+}
+
+func NewUserRepo(pool *pgxpool.Pool) *UserRepo {
+	return &UserRepo{pool: pool}
+}
+
+func (r *UserRepo) Insert(ctx context.Context, u *domain.User) error {
+	sql, args, err := psql.Insert("users").
+		Columns(userColumns...).
+		Values(u.ID, u.Email, u.PasswordHash, string(u.Role), u.CreatedAt, u.UpdatedAt).
+		ToSql()
+	if err != nil {
+		return err
+	}
+	if _, err := conn(ctx, r.pool).Exec(ctx, sql, args...); err != nil {
+		// A concurrent insert of the same email surfaces as a unique violation
+		// on uq_users_email; translate it to the port's sentinel so the use
+		// case never sees a driver type.
+		if isUniqueViolation(err) {
+			return usecase.ErrEmailExists
+		}
+		return err
+	}
+	return nil
+}
+
+func (r *UserRepo) GetByEmail(ctx context.Context, email string) (*domain.User, error) {
+	return r.getBy(ctx, sq.Eq{"email": email})
+}
+
+func (r *UserRepo) GetByID(ctx context.Context, id uuid.UUID) (*domain.User, error) {
+	return r.getBy(ctx, sq.Eq{"id": id})
+}
+
+func (r *UserRepo) getBy(ctx context.Context, pred sq.Sqlizer) (*domain.User, error) {
+	sql, args, err := psql.Select(userColumns...).From("users").Where(pred).ToSql()
+	if err != nil {
+		return nil, err
+	}
+	return scanUser(conn(ctx, r.pool).QueryRow(ctx, sql, args...))
+}
+
+func scanUser(row pgx.Row) (*domain.User, error) {
+	var (
+		u    domain.User
+		role string
+	)
+	if err := row.Scan(&u.ID, &u.Email, &u.PasswordHash, &role, &u.CreatedAt, &u.UpdatedAt); err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, usecase.ErrUserNotFound
+		}
+		return nil, err
+	}
+	u.Role = domain.Role(role)
+	return &u, nil
+}
+
+func isUniqueViolation(err error) bool {
+	var pgErr *pgconn.PgError
+	return errors.As(err, &pgErr) && pgErr.Code == uniqueViolation
+}