"""Async database engine.

A single lazily-created async engine for the process. The repository layer
(coming with the data model) will build sessions on top of this; for now it
backs the readiness probe.
"""

from sqlalchemy.ext.asyncio import AsyncEngine, create_async_engine

from app.core.config import get_settings

_engine: AsyncEngine | None = None


def get_engine() -> AsyncEngine:
    global _engine
    if _engine is None:
        _engine = create_async_engine(
            get_settings().database_url,
            pool_pre_ping=True,
        )
    return _engine