from pathlib import Path

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

from .config import settings


class Base(DeclarativeBase):
    pass


if settings.database_url.startswith("sqlite"):
    Path(settings.database_url.replace("sqlite:///", "")).parent.mkdir(parents=True, exist_ok=True)
    engine = create_engine(settings.database_url, connect_args={"check_same_thread": False})
else:
    engine = create_engine(settings.database_url, pool_pre_ping=True)

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


def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        # A request may exit through an exception or an early return before a
        # route explicitly commits.  Roll back first so any checked-out
        # connection is returned to QueuePool in a clean state, then close the
        # Session itself.  Session.close() also rolls back, but doing it here
        # makes the lifecycle guarantee explicit and observable in tests.
        try:
            db.rollback()
        finally:
            db.close()