from __future__ import annotations

from collections.abc import Iterator

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

from ypms.settings import get_settings


class Base(DeclarativeBase):
    pass


_engine: Engine | None = None
_SessionLocal: sessionmaker[Session] | None = None


def engine() -> Engine:
    global _engine
    if _engine is None:
        # hide_parameters: keep bound values (PII) out of exception text and logs.
        _engine = create_engine(
            get_settings().database_url, pool_pre_ping=True, future=True, hide_parameters=True
        )
    return _engine


def session_factory() -> sessionmaker[Session]:
    global _SessionLocal
    if _SessionLocal is None:
        _SessionLocal = sessionmaker(bind=engine(), autoflush=False, autocommit=False, future=True)
    return _SessionLocal


def get_db() -> Iterator[Session]:
    db = session_factory()()
    try:
        yield db
    finally:
        db.close()