from __future__ import annotations

from sqlalchemy import create_engine, text
from sqlalchemy.engine import Engine

from app.config import settings


_engine: Engine | None = None


def get_engine() -> Engine:
    global _engine
    if _engine is None:
        _engine = create_engine(settings.database_url, pool_pre_ping=True, future=True)
    return _engine


def ping() -> dict[str, object]:
    """Smoke-test: DB 연결 + 확장 확인."""
    eng = get_engine()
    with eng.connect() as conn:
        version = conn.execute(text("SELECT version()")).scalar()
        exts = conn.execute(
            text(
                "SELECT extname FROM pg_extension "
                "WHERE extname IN ('timescaledb','vector','pg_trgm') ORDER BY extname"
            )
        ).scalars().all()
    return {"server": version, "extensions": list(exts)}