from collections.abc import AsyncIterator

from sqlalchemy.ext.asyncio import (
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)

from ..config import settings


def _normalize_url(url: str) -> str:
    """Convert any postgres URL flavor to the asyncpg driver form."""
    if url.startswith("postgres://"):
        url = "postgresql://" + url[len("postgres://") :]
    if url.startswith("postgresql://") and "+asyncpg" not in url:
        url = "postgresql+asyncpg://" + url[len("postgresql://") :]
    return url


engine = create_async_engine(
    _normalize_url(settings.DATABASE_URL),
    pool_size=10,
    max_overflow=20,
    pool_pre_ping=True,
)

SessionLocal = async_sessionmaker(engine, expire_on_commit=False, class_=AsyncSession)


async def get_db() -> AsyncIterator[AsyncSession]:
    async with SessionLocal() as session:
        yield session