from typing import Optional, List
from datetime import date
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.batch import Batch


class BatchRepository:
    def __init__(self, db: AsyncSession):
        self.db = db

    async def get_by_id(self, batch_id: int) -> Optional[Batch]:
        result = await self.db.execute(select(Batch).where(Batch.id == batch_id))
        return result.scalar_one_or_none()

    async def get_by_medicine_id(self, medicine_id: int) -> List[Batch]:
        result = await self.db.execute(
            select(Batch)
            .where(Batch.medicine_id == medicine_id)
            .order_by(Batch.expiry_date)
        )
        return list(result.scalars().all())

    async def get_expiring_before(self, target_date: date) -> List[Batch]:
        result = await self.db.execute(
            select(Batch)
            .where(
                Batch.expiry_date <= target_date,
                Batch.is_expired == False,
                Batch.quantity > 0
            )
        )
        return list(result.scalars().all())

    async def create(self, data: dict) -> Batch:
        batch = Batch(**data)
        self.db.add(batch)
        await self.db.flush()
        return batch

    async def update(self, batch_id: int, data: dict) -> Optional[Batch]:
        batch = await self.get_by_id(batch_id)
        if not batch:
            return None
        for key, value in data.items():
            setattr(batch, key, value)
        await self.db.flush()
        return batch

    async def delete(self, batch_id: int) -> bool:
        batch = await self.get_by_id(batch_id)
        if not batch:
            return False
        await self.db.delete(batch)
        return True