"""Thread-local DB session bridge for ported WESP services."""

from __future__ import annotations

from contextlib import contextmanager
from contextvars import ContextVar
from typing import Iterator

from sqlalchemy.orm import Session

_current_session: ContextVar[Session | None] = ContextVar("wesp_current_session", default=None)


class _WespDB:
    @property
    def session(self) -> Session:
        db = _current_session.get()
        if db is None:
            raise RuntimeError("wesp_bridge_db: no active session — use wesp_db_session()")
        return db


db = _WespDB()


@contextmanager
def wesp_db_session(existing: Session | None = None) -> Iterator[Session]:
    if existing is not None:
        token = _current_session.set(existing)
        try:
            yield existing
        finally:
            _current_session.reset(token)
        return
    from app.core.database import session_scope

    with session_scope() as session:
        token = _current_session.set(session)
        try:
            yield session
        finally:
            _current_session.reset(token)