todo-api/internal/service/user_service.go

package service

import (
	"context"

	"code.nochebuena.dev/go/rbac"
	"code.nochebuena.dev/go/todo-api/internal/domain"
	"code.nochebuena.dev/go/todo-api/internal/repository"
)

// CreateUserRequest is the input for creating a new user.
// CanRead / CanWrite seed the permission bits for the todos resource immediately.
type CreateUserRequest struct {
	Name     string `json:"name"     validate:"required,min=1,max=100"`
	Email    string `json:"email"    validate:"required,email"`
	CanRead  bool   `json:"can_read"`
	CanWrite bool   `json:"can_write"`
}

// UserService handles user business logic.
type UserService interface {
	FindAll(ctx context.Context) ([]domain.User, error)
	Create(ctx context.Context, req CreateUserRequest) (domain.User, error)
}

type userService struct {
	repo  repository.UserRepository
	idGen func() string
}

// NewUserService returns a UserService. idGen is called to mint new user IDs (e.g. uuid.NewString).
func NewUserService(repo repository.UserRepository, idGen func() string) UserService {
	return &userService{repo: repo, idGen: idGen}
}

func (s *userService) FindAll(ctx context.Context) ([]domain.User, error) {
	return s.repo.FindAll(ctx)
}

func (s *userService) Create(ctx context.Context, req CreateUserRequest) (domain.User, error) {
	user, err := s.repo.Create(ctx, domain.User{
		ID:    s.idGen(),
		Name:  req.Name,
		Email: req.Email,
	})
	if err != nil {
		return domain.User{}, err
	}

	// Build and persist permission mask from the request flags.
	var mask rbac.PermissionMask
	if req.CanRead {
		mask = mask.Grant(domain.PermReadTodo)
	}
	if req.CanWrite {
		mask = mask.Grant(domain.PermWriteTodo)
	}
	if mask != 0 {
		if err := s.repo.SetPermissions(ctx, user.ID, domain.ResourceTodos, mask); err != nil {
			return domain.User{}, err
		}
	}

	return user, nil
}