from contextlib import asynccontextmanager
from typing import AsyncGenerator

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

from app.config import settings


class Base(DeclarativeBase):
    pass


# ─── Async engine (FastAPI) ───────────────────────────────────────────────────

async_engine = create_async_engine(
    settings.DATABASE_URL,
    echo=False,
    pool_size=10,
    max_overflow=20,
)

AsyncSessionLocal = async_sessionmaker(
    async_engine,
    expire_on_commit=False,
    class_=AsyncSession,
)


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    async with AsyncSessionLocal() as session:
        yield session


# ─── Sync engine (Celery workers) ────────────────────────────────────────────

sync_engine = create_engine(
    settings.SYNC_DATABASE_URL,
    pool_size=5,
    max_overflow=10,
    pool_pre_ping=True,
)

SyncSessionLocal = sessionmaker(
    bind=sync_engine,
    autoflush=False,
    autocommit=False,
)


def get_sync_db() -> Session:
    return SyncSessionLocal()