"""数据库连接与初始化。"""
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, declarative_base

from .config import settings

# SQLite 需要 check_same_thread=False 才能在多线程/异步下用
connect_args = (
    {"check_same_thread": False}
    if settings.database_url.startswith("sqlite")
    else {}
)

engine = create_engine(settings.database_url, connect_args=connect_args)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()


def get_db():
    """FastAPI 依赖：每请求一个 session，用完关闭。"""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def init_db():
    """建表。"""
    from . import models  # noqa: F401  确保模型被导入
    Base.metadata.create_all(bind=engine)