"""asyncpg connection pool and DB access helpers."""

from collections.abc import AsyncIterator
from contextlib import asynccontextmanager

import asyncpg

from app.config import get_settings

_pool: asyncpg.Pool | None = None


async def init_db_pool() -> None:
    """Create global pool (call from FastAPI lifespan)."""
    global _pool
    if _pool is not None:
        return
    s = get_settings()
    _pool = await asyncpg.create_pool(
        host=s.db_host,
        port=s.db_port,
        user=s.db_user,
        password=s.db_password,
        database=s.db_name,
        min_size=1,
        max_size=10,
    )


async def close_db_pool() -> None:
    global _pool
    if _pool is not None:
        await _pool.close()
        _pool = None


def get_pool() -> asyncpg.Pool:
    if _pool is None:
        raise RuntimeError("DB pool not initialized; call init_db_pool() first")
    return _pool


@asynccontextmanager
async def get_db() -> AsyncIterator[asyncpg.Connection]:
    """Async context manager yielding a connection from the pool."""
    pool = get_pool()
    async with pool.acquire() as conn:
        yield conn