from __future__ import annotations

from typing import Generic, TypeVar

from sqlalchemy import select
from sqlalchemy.orm import Session

from supply_infra.db.base import Base

T = TypeVar("T", bound=Base)


class BaseRepository(Generic[T]):
    """Generic CRUD repository — subclass per entity."""

    model: type[T]

    def __init__(self, session: Session) -> None:
        self.session = session

    def get_by_id(self, id: int) -> T | None:
        return self.session.get(self.model, id)

    def list_all(self, *, limit: int = 100, offset: int = 0) -> list[T]:
        stmt = select(self.model).limit(limit).offset(offset)
        return list(self.session.scalars(stmt).all())

    def add(self, entity: T) -> T:
        self.session.add(entity)
        self.session.flush()
        return entity

    def delete(self, entity: T) -> None:
        self.session.delete(entity)