"""SQLAlchemy engine + scoped session for the app."""
from __future__ import annotations

from sqlalchemy import create_engine
from sqlalchemy.orm import DeclarativeBase, scoped_session, sessionmaker


class Base(DeclarativeBase):
    pass


_engine = None
_Session: scoped_session | None = None


def init_engine(url: str):
    global _engine, _Session
    _engine = create_engine(url, pool_pre_ping=True, future=True)
    _Session = scoped_session(sessionmaker(bind=_engine, expire_on_commit=False, future=True))
    return _engine


def get_engine():
    if _engine is None:
        raise RuntimeError("Engine not initialized — call init_engine() in create_app")
    return _engine


def db_session():
    if _Session is None:
        raise RuntimeError("Session factory not initialized")
    return _Session