from typing import Optional
from pydantic_settings import BaseSettings, SettingsConfigDict
from pydantic import Field

from servers.base import BaseService
from sqlmodel import create_engine
from sqlmodel.ext.asyncio.session import AsyncSession
from sqlalchemy import Engine

class DatabaseSettings(BaseSettings):
  """
  数据库服务配置类
  """
  model_config = SettingsConfigDict(
    env_prefix="database_",
    case_sensitive=False,
    extra="ignore",
  )
  url: Optional[str] = Field(None, description="数据库连接URL")

class DatabaseService(BaseService[Engine]):
  """
  数据库服务类,定义了数据库服务的基本状态和操作
  """
  service_name: str = "database"

  async def _initialize(self) -> Engine:
    """
    初始化数据库服务
    """
    setting = DatabaseSettings()
    if not setting.url:
      raise ValueError("数据库连接URL不能为空")
    engine = create_engine(setting.url)
    return engine
  
  async def _shutdown(self) -> None:
    """
    关闭数据库服务
    """
    if not self._instance:
      return
    self._instance.dispose()
  
  async def _check_health(self) -> bool:
    """
    检查数据库服务健康状态
    """
    if not self._instance:
      return False
    async with AsyncSession(self._instance) as session:
      await session.exec("SELECT 1")
      return True

database_service = DatabaseService()

__all__ = [
  "database_service",
]