from typing import Optional
from sqlalchemy.ext.asyncio import AsyncSession

from dto.categories import CategoryDTO
from repositories import CategoriesRepository


class CategoryService:
    def __init__(self, category_repo: CategoriesRepository):
        self.category_repo = category_repo

    async def get_children(
        self, session: AsyncSession, parent_id: Optional[int] = None
    ) -> list[CategoryDTO]:
        result = await self.category_repo.get_category_by_parent_id(session, parent_id)
        return [
            CategoryDTO(x.id, x.name) for x in result
        ]  # FIXME: Optimization may be required here - O(n)