from typing import List, Optional

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from app.models.category import Category
from app.schemas.category import CategoryCreate, CategoryUpdate


async def get_categories(db: AsyncSession) -> List[Category]:
    """Get all categories."""
    result = await db.execute(select(Category))
    return result.scalars().all()


async def get_category(db: AsyncSession, category_id: int) -> Optional[Category]:
    """Get a category by ID."""
    return await db.get(Category, category_id)


async def get_category_with_products(
    db: AsyncSession, category_id: int
) -> Optional[Category]:
    """Get a category with related products."""
    query = (
        select(Category)
        .where(Category.id == category_id)
        .options(selectinload(Category.products))
    )
    result = await db.execute(query)
    return result.scalar_one_or_none()


async def create_category(db: AsyncSession, category: CategoryCreate) -> Category:
    """Create a new category."""
    db_category = Category(**category.model_dump())
    db.add(db_category)
    await db.commit()
    await db.refresh(db_category)
    return db_category


async def update_category(
    db: AsyncSession, db_category: Category, category_update: CategoryUpdate
) -> Category:
    """Update a category."""
    update_data = category_update.model_dump(exclude_unset=True)
    for field, value in update_data.items():
        setattr(db_category, field, value)

    await db.commit()
    await db.refresh(db_category)
    return db_category


async def delete_category(db: AsyncSession, db_category: Category) -> None:
    """Delete a category."""
    await db.delete(db_category)
    await db.commit()