add create user method

internal/app/server.go

@@ -2,21 +2,28 @@ package app
 
 import (
 	"context"
+	"errors"
 
 	"git.3crabs.ru/save_my_money/smm_core/internal/services/category"
+	"git.3crabs.ru/save_my_money/smm_core/internal/services/user"
 	proto "git.3crabs.ru/save_my_money/smm_core/proto"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 )
 
 type Server struct {
 	proto.UnsafeSmmCoreServer
 	categoryService *category.CategoryService
+	userService     *user.UserService
 }
 
 func NewServer(
 	categoryService *category.CategoryService,
+	userService *user.UserService,
 ) proto.SmmCoreServer {
 	return &Server{
 		categoryService: categoryService,
+		userService:     userService,
 	}
 }
 
@@ -24,6 +31,25 @@ func (s *Server) Ping(_ context.Context, _ *proto.PingReq) (*proto.PingRsp, erro
 	return &proto.PingRsp{}, nil
 }
 
+func (s *Server) AddUser(ctx context.Context, req *proto.CreateUserReq) (*proto.User, error) {
+	res, err := s.userService.AddUser(
+		ctx,
+		&user.UserEntity{
+			Username: req.Username,
+		},
+	)
+	if err != nil {
+		if errors.Is(err, &user.UsernameAlreadyExistsErr{}) {
+			return nil, status.Error(codes.AlreadyExists, "Пользователь с таким username уже существует")
+		}
+		return nil, err
+	}
+	return &proto.User{
+		Id:       int32(res.Id),
+		Username: res.Username,
+	}, nil
+}
+
 func (s *Server) AddCategory(ctx context.Context, req *proto.CreateCategoryReq) (*proto.Category, error) {
 	res, err := s.categoryService.AddCategory(
 		ctx,

internal/services/user/requests.restbook

@@ -0,0 +1 @@
+[{"kind":1,"language":"markdown","value":"# Добавление пользователя","outputs":[]},{"kind":2,"language":"rest-book","value":"POST http://localhost:8090/users\n\n{\n    \"username\": \"foo\"\n}","outputs":[{"mime":"x-application/rest-book","value":{"status":409,"statusText":"Conflict","headers":{"Date":"Wed, 20 Nov 2024 08:30:32 GMT","Content-Type":"application/json","Content-Length":"111"},"config":{"timeout":10000,"xsrfCookieName":"XSRF-TOKEN","xsrfHeaderName":"X-XSRF-TOKEN","headers":{"Accept":"application/json, text/plain, */*","Content-Type":"application/json","User-Agent":"rest-book","Content-Length":18}},"request":{"method":"POST","httpVersion":"1.1","responseUrl":"http://localhost:8090/users","timeout":10000,"headers":{"User-Agent":"rest-book"},"data":{"username":"bar"}},"data":{"code":6,"message":"Пользователь с таким username уже существует","details":[]}}},{"mime":"text/x-json","value":{"status":409,"statusText":"Conflict","headers":{"Date":"Wed, 20 Nov 2024 08:30:32 GMT","Content-Type":"application/json","Content-Length":"111"},"config":{"timeout":10000,"xsrfCookieName":"XSRF-TOKEN","xsrfHeaderName":"X-XSRF-TOKEN","headers":{"Accept":"application/json, text/plain, */*","Content-Type":"application/json","User-Agent":"rest-book","Content-Length":18}},"request":{"method":"POST","httpVersion":"1.1","responseUrl":"http://localhost:8090/users","timeout":10000,"headers":{"User-Agent":"rest-book"},"data":{"username":"bar"}},"data":{"code":6,"message":"Пользователь с таким username уже существует","details":[]}}},{"mime":"text/html","value":"[object Object]"}]}]

internal/services/user/user_service.go

@@ -0,0 +1,51 @@
+package user
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgconn"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+type UserEntity struct {
+	Id       int
+	Username string
+}
+
+type UsernameAlreadyExistsErr struct{}
+
+func (e *UsernameAlreadyExistsErr) Error() string {
+	return "username already exists error"
+}
+
+type UserService struct {
+	db *pgxpool.Pool
+}
+
+func NewUserService(
+	db *pgxpool.Pool,
+) *UserService {
+	return &UserService{
+		db: db,
+	}
+}
+
+func (s *UserService) AddUser(ctx context.Context, user *UserEntity) (*UserEntity, error) {
+	query := `INSERT INTO users (username) VALUES (@username) RETURNING id`
+	args := pgx.NamedArgs{
+		"username": user.Username,
+	}
+	if err := s.db.QueryRow(ctx, query, args).Scan(&user.Id); err != nil {
+		var pgErr *pgconn.PgError
+		if errors.As(err, &pgErr) {
+			if pgErr.Code == "23505" && pgErr.ConstraintName == "users_username_key" { // unique_violation
+				return nil, &UsernameAlreadyExistsErr{}
+			}
+		}
+		return nil, fmt.Errorf("unable to insert row: %w", err)
+	}
+	return user, nil
+}