from typing import cast

from psycopg_pool import AsyncConnectionPool

from app.config import get_settings

_pool: AsyncConnectionPool | None = None


async def get_pool() -> AsyncConnectionPool:
    global _pool  # noqa: PLW0603 — lazy singleton, by design
    if _pool is None:
        settings = get_settings()
        _pool = AsyncConnectionPool(
            conninfo=settings.database_url,
            min_size=1,
            max_size=10,
            open=False,
        )
        await _pool.open()
    return _pool


async def close_pool() -> None:
    global _pool  # noqa: PLW0603 — lazy singleton, by design
    if _pool is not None:
        await _pool.close()
        _pool = None


async def check_db() -> bool:
    pool = await get_pool()
    async with pool.connection() as conn, conn.cursor() as cur:
        await cur.execute("SELECT 1")
        row = await cur.fetchone()
        return cast(tuple[int], row)[0] == 1