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

DATABASE_URL = os.environ["DATABASE_URL"]

engine = create_engine(DATABASE_URL, pool_pre_ping=True)

SessionLocal = sessionmaker(bind=engine, autocommit=False, autoflush=False)


class Base(DeclarativeBase):
    pass


def get_db():
    """FastAPI dependency — yields a DB session and closes it when done."""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()