"""
数据库连接模块
SQLite 异步连接配置和会话管理
"""
from sqlalchemy import text
from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession, async_sessionmaker
from sqlalchemy.orm import declarative_base
from app.config import settings

# 创建异步引擎
engine = create_async_engine(
    settings.database_url,
    echo=settings.database_echo,  # 控制是否打印 SQL
    future=True,
    connect_args={"timeout": 60},  # 增大连接超时
    pool_size=50,                  # 基准连接池大小
    max_overflow=100,              # 最大允许溢出的连接数
    pool_recycle=3600,             # 每小时回收连接防止失效
    pool_pre_ping=True             # 每次使用连接前进行活跃性检测
)

# 创建异步会话工厂
AsyncSessionLocal = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False,
    autocommit=False,
    autoflush=False
)

# 创建 Base 类
Base = declarative_base()


async def get_db() -> AsyncSession:
    """
    获取数据库会话
    用于 FastAPI 依赖注入
    """
    async with AsyncSessionLocal() as session:
        try:
            yield session
        finally:
            await session.close()


async def init_db():
    """
    初始化数据库
    创建所有表
    """
    async with engine.begin() as conn:
        await conn.execute(text("PRAGMA journal_mode=WAL"))
        await conn.run_sync(Base.metadata.create_all)


async def close_db():
    """
    关闭数据库连接
    """
    await engine.dispose()