add add user method

internal/repos/users_repo/repo.go

@@ -0,0 +1,50 @@
+package users_repo
+
+import (
+	"context"
+	"errors"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+type UsersRepo struct {
+	pool *pgxpool.Pool
+}
+
+func NewUserRepo(pool *pgxpool.Pool) *UsersRepo {
+	return &UsersRepo{
+		pool: pool,
+	}
+}
+
+func (s *UsersRepo) AddUser(
+	ctx context.Context,
+	username string,
+	email string,
+	passwoedHash string,
+	role string,
+) error {
+	tag, err := s.pool.Exec(
+		ctx,
+		`INSERT INTO users (username, email, password_hash, role)
+		SELECT $1, $2, $3, $4
+		WHERE NOT EXISTS (
+			SELECT 1 FROM users 
+			WHERE username = $5 OR email = $6
+		)`,
+		username,
+		email,
+		passwoedHash,
+		role,
+
+		username,
+		email,
+	)
+	if err != nil {
+		return err
+	}
+	if tag.RowsAffected() == 0 {
+		return errors.New("username или email уже используется")
+	}
+	return nil
+}