from abc import abstractmethod, ABC
from typing import Generic, Optional, TypeVar

from pydantic import BaseModel
from pydantic_settings.main import asyncio

class HealthStatus(BaseModel):
  """
  服务健康状态类
  """
  service_name: str
  is_initialized: bool = False
  is_healthy: bool = False
  detail: Optional[str] = None

T = TypeVar("T", bound="BaseService")
class BaseService(ABC, Generic[T]):
  """
  基础服务类，定义了服务的基本状态和操作
  """
  _lock: asyncio.Lock = asyncio.Lock()
  _instance: Optional[T] = None

  @property
  @abstractmethod
  def service_name(self) -> str:
    """
    返回服务名称
    """
  
  @abstractmethod
  async def _initialize(self) -> T:
    """
    初始化服务
    """
  
  @abstractmethod
  async def _shutdown(self) -> None:
    """
    关闭服务
    """
  
  @abstractmethod
  async def _health_check(self) -> bool:
    """
    健康检查服务
    """
  
  async def check_health(self) -> HealthStatus:
    """
    检查服务健康状态
    """
    async with self._lock:
      if self._instance is None:
        return HealthStatus(
          service_name=self.service_name,
          is_initialized=False,
          is_healthy=False,
        )
      try:
        is_healthy = await self._health_check()
        return HealthStatus(
          service_name=self.service_name, 
          is_initialized=True,
          is_healthy=is_healthy,
          detail="success",
        )
      except Exception as e:
        return HealthStatus(
          service_name=self.service_name, 
          is_initialized=True,
          is_healthy=False,
          detail=str(e),
        )
  
  async def initialize(self) -> None:
    """
    初始化服务
    """
    async with self._lock:
      if self._instance is not None:
        await self._shutdown()
      try:
        self._instance = await self._initialize()
      except Exception as e:
        self._instance = None
        raise e

  async def shutdown(self) -> None:
    """
    关闭服务
    """
    async with self._lock:
      if self._instance is None:
        return
      await self._shutdown()
      self._instance = None

  async def get_instance(self, force_initialize: bool = False) -> T:
    """
    获取服务实例
    """
    if self._instance is None and force_initialize:
      await self.initialize()
    if self._instance is None:
      raise ValueError(f"Service {self.service_name} is not initialized.")
    return self._instance

__all__ = [
  "BaseService",
  "HealthStatus",
]