"""异步 SQLAlchemy 数据库连接。"""
from __future__ import annotations

from collections.abc import AsyncGenerator

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

from app.config import settings


class Base(DeclarativeBase):
    """所有 ORM 模型的基类。"""


engine = create_async_engine(
    settings.database_url,
    echo=False,
    pool_size=5,
    max_overflow=10,
    pool_pre_ping=True,
    pool_recycle=1800,
)

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


async def get_session() -> AsyncGenerator[AsyncSession, None]:
    """FastAPI 依赖:请求级 session。"""
    async with AsyncSessionLocal() as session:
        try:
            yield session
        finally:
            await session.close()


async def init_db() -> None:
    """开发期用,生产请用 alembic。"""
    # import models to register them
    from app.models import article, source, user  # noqa: F401

    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)