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

from app.config import settings

engine = create_async_engine(settings.database_url, echo=False, connect_args={"check_same_thread": False})
async_session = async_sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)


class Base(DeclarativeBase):
    pass


async def init_db():
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)
        # 启用 WAL 模式，提升并发读写性能
        await conn.execute(text("PRAGMA journal_mode=WAL"))
        await conn.execute(text("PRAGMA busy_timeout=5000"))


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