"""Engine / session factory and the FastAPI DB dependency."""
from collections.abc import Generator

from sqlalchemy import create_engine
from sqlalchemy.orm import Session, sessionmaker

from app.core.config import settings

engine = create_engine(
    settings.sqlalchemy_url,
    pool_pre_ping=True,
    pool_size=settings.POSTGRES_POOL_SIZE,
    max_overflow=settings.POSTGRES_MAX_OVERFLOW,
    future=True,
)

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


def get_db() -> Generator[Session, None, None]:
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()