from typing import List, Optional, Tuple
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.medicine import Medicine
from app.schemas.medicine import MedicineCreate, MedicineUpdate, MedicineWithStock
from app.repositories.medicine import MedicineRepository


class MedicineService:
    def __init__(self, db: AsyncSession):
        self.db = db
        self.repo = MedicineRepository(db)

    async def get_medicines(
        self,
        category_id: Optional[int] = None,
        search: Optional[str] = None,
        page: int = 1,
        page_size: int = 20
    ) -> Tuple[List[MedicineWithStock], int]:
        medicines, total = await self.repo.get_list(
            category_id=category_id,
            search=search,
            page=page,
            page_size=page_size
        )

        result = []
        for medicine in medicines:
            total_quantity = sum(b.quantity for b in medicine.batches if not b.is_expired)

            nearest_expiry = None
            for batch in medicine.batches:
                if not batch.is_expired:
                    if nearest_expiry is None or batch.expiry_date < nearest_expiry:
                        nearest_expiry = batch.expiry_date

            medicine_with_stock = MedicineWithStock(
                **medicine.__dict__,
                total_quantity=total_quantity,
                nearest_expiry_date=nearest_expiry,
                batch_count=len([b for b in medicine.batches if not b.is_expired])
            )
            result.append(medicine_with_stock)

        return result, total

    async def get_medicine(self, medicine_id: int) -> Optional[Medicine]:
        return await self.repo.get_by_id(medicine_id)

    async def create_medicine(self, data: MedicineCreate, user_id: int) -> Medicine:
        medicine_data = data.model_dump()
        medicine_data['created_by'] = user_id
        return await self.repo.create(medicine_data)

    async def update_medicine(self, medicine_id: int, data: MedicineUpdate) -> Optional[Medicine]:
        update_data = data.model_dump(exclude_unset=True)
        return await self.repo.update(medicine_id, update_data)

    async def delete_medicine(self, medicine_id: int) -> bool:
        return await self.repo.delete(medicine_id)

    async def search_medicines(self, query: str) -> List[Medicine]:
        return await self.repo.search(query)