"""Database engine + session factory."""
from __future__ import annotations

from contextlib import asynccontextmanager
from typing import AsyncIterator

from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
from sqlalchemy.orm import DeclarativeBase

from app.config import settings


class Base(DeclarativeBase):
    pass


_engine_kwargs: dict = dict(
    echo=False,
    pool_pre_ping=True,
)
# Pool size params only for Postgres/MySQL (not SQLite)
if "sqlite" not in settings.database_url:
    _engine_kwargs.update(pool_size=10, max_overflow=20)

engine = create_async_engine(settings.database_url, **_engine_kwargs)

AsyncSessionLocal = async_sessionmaker(
    engine, class_=AsyncSession, expire_on_commit=False, autoflush=False
)


@asynccontextmanager
async def get_db() -> AsyncIterator[AsyncSession]:
    async with AsyncSessionLocal() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise


async def get_db_dep() -> AsyncIterator[AsyncSession]:
    """FastAPI dependency."""
    async with AsyncSessionLocal() as session:
        try:
            yield session
        finally:
            await session.close()