from typing import Optional
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from sqlalchemy.orm import aliased

from db.models import Category


class CategoriesRepository:
    async def get_category_by_id(
        self, session: AsyncSession, category_id: int
    ) -> Optional[Category]:
        stmt = select(Category).where(Category.id == category_id)
        return await session.scalar(stmt)

    async def get_categories_by_parent_id(
        self, session: AsyncSession, parent_id: Optional[int] = None
    ) -> list[Category]:
        stmt = select(Category).where(Category.parent_id == parent_id)
        result = await session.scalars(stmt)

        return list(result)

    async def get_category_path(self, session: AsyncSession, category_id: int):
        base = select(Category.id, Category.parent_id, Category.name).where(
            Category.id == category_id
        )

        cte = base.cte(name="path", recursive=True)

        parent = aliased(Category)

        cte = cte.union_all(
            select(parent.id, parent.parent_id, parent.name).join(
                cte, cte.c.parent_id == parent.id
            )
        )

        stmt = select(cte)

        result = await session.execute(stmt)

        rows = result.all()

        return list(reversed(rows))

    async def add_category(
        self, session: AsyncSession, *, name: str, parent_id: Optional[int]
    ) -> Category:
        category = Category(name=name, parent_id=parent_id)

        session.add(category)
        await session.commit()

        return category