# app/crud/item.py
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.future import select
from sqlalchemy import delete as sql_delete, update as sql_update # Use aliases
from typing import Optional, List as PyList
from datetime import datetime, timezone
from app.models import Item as ItemModel
from app.schemas.item import ItemCreate, ItemUpdate

async def create_item(db: AsyncSession, item_in: ItemCreate, list_id: int, user_id: int) -> ItemModel:
    """Creates a new item record for a specific list."""
    db_item = ItemModel(
        name=item_in.name,
        quantity=item_in.quantity,
        list_id=list_id,
        added_by_id=user_id,
        is_complete=False # Default on creation
    )
    db.add(db_item)
    await db.commit()
    await db.refresh(db_item)
    return db_item

async def get_items_by_list_id(db: AsyncSession, list_id: int) -> PyList[ItemModel]:
    """Gets all items belonging to a specific list, ordered by creation time."""
    result = await db.execute(
        select(ItemModel)
        .where(ItemModel.list_id == list_id)
        .order_by(ItemModel.created_at.asc()) # Or desc() if preferred
    )
    return result.scalars().all()

async def get_item_by_id(db: AsyncSession, item_id: int) -> Optional[ItemModel]:
    """Gets a single item by its ID."""
    result = await db.execute(select(ItemModel).where(ItemModel.id == item_id))
    return result.scalars().first()

async def update_item(db: AsyncSession, item_db: ItemModel, item_in: ItemUpdate, user_id: int) -> ItemModel:
    """Updates an existing item record."""
    update_data = item_in.model_dump(exclude_unset=True)
    now_utc = datetime.now(timezone.utc)

    if 'is_complete' in update_data:
        if update_data['is_complete'] is True and item_db.completed_by_id is None:
            update_data['completed_by_id'] = user_id
        elif update_data['is_complete'] is False:
            update_data['completed_by_id'] = None

    if 'price' in update_data:
        if update_data['price'] is not None:
            update_data['price_added_by_id'] = user_id
            update_data['price_added_at'] = now_utc
        else:
            update_data['price_added_by_id'] = None
            update_data['price_added_at'] = None

    for key, value in update_data.items():
        setattr(item_db, key, value)

    db.add(item_db)
    await db.commit()
    await db.refresh(item_db)
    return item_db

async def delete_item(db: AsyncSession, item_db: ItemModel) -> None:
    """Deletes an item record."""
    await db.delete(item_db)
    await db.commit()
    return None # Or return True/False