import os
from contextlib import contextmanager
from pathlib import Path
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, Session
from db.models import Base

_DB_PATH = Path(__file__).parent.parent.parent / "stockmind.db"
_ENGINE = None
_SessionLocal = None


def _get_engine():
    global _ENGINE
    if _ENGINE is None:
        _ENGINE = create_engine(f"sqlite:///{_DB_PATH}", connect_args={"check_same_thread": False})
    return _ENGINE


def init_db():
    engine = _get_engine()
    Base.metadata.create_all(engine)
    global _SessionLocal
    _SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False)


@contextmanager
def get_session() -> Session:
    global _SessionLocal
    if _SessionLocal is None:
        init_db()
    session = _SessionLocal()
    try:
        yield session
    except Exception:
        session.rollback()
        raise
    finally:
        session.close()