sessions/internal/bundb/user.go

package bundb

import (
	"context"
	"database/sql"
	"errors"
	"fmt"

	"gitea.dwysokinski.me/twhelp/sessions/internal/bundb/internal/model"
	"gitea.dwysokinski.me/twhelp/sessions/internal/domain"
	"github.com/jackc/pgerrcode"
	"github.com/uptrace/bun"
	"github.com/uptrace/bun/driver/pgdriver"
)

type User struct {
	db *bun.DB
}

func NewUser(db *bun.DB) *User {
	return &User{db: db}
}

func (u *User) Create(ctx context.Context, params domain.CreateUserParams) (domain.User, error) {
	user := model.NewUser(params)

	if _, err := u.db.NewInsert().
		Model(&user).
		Returning("*").
		Exec(ctx); err != nil {
		return domain.User{}, fmt.Errorf(
			"something went wrong while inserting user into the db: %w",
			mapCreateUserError(err, params),
		)
	}

	return user.ToDomain(), nil
}

func (u *User) Get(ctx context.Context, id int64) (domain.User, error) {
	var user model.User

	if err := u.db.NewSelect().
		Model(&user).
		Where("id = ?", id).
		Scan(ctx); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return domain.User{}, domain.UserNotFoundError{ID: id}
		}
		return domain.User{}, fmt.Errorf(
			"something went wrong while selecting user (id=%d) from the db: %w",
			id,
			err,
		)
	}

	return user.ToDomain(), nil
}

func mapCreateUserError(err error, params domain.CreateUserParams) error {
	var pgError pgdriver.Error
	if !errors.As(err, &pgError) {
		return err
	}

	code := pgError.Field('C')
	constraint := pgError.Field('n')
	switch {
	case code == pgerrcode.UniqueViolation && constraint == "users_name_lower_key":
		return domain.UsernameAlreadyTakenError{
			Name: params.Name(),
		}
	default:
		return err
	}
}