import httpx
from typing import Optional, Dict, Any, Tuple
from app.core.config import settings
from app.core.exceptions import BusinessError

class WechatLoginError(Exception):
    """微信登录错误"""
    pass

async def code2session(code: str) -> Tuple[str, Optional[str]]:
    """
    使用微信登录code获取openid和unionid
    
    Args:
        code: 微信临时登录凭证
        
    Returns:
        Tuple[str, Optional[str]]: (openid, unionid)
        
    Raises:
        BusinessError: 当微信API调用失败时
    """
    url = "https://api.weixin.qq.com/sns/jscode2session"
    params = {
        "appid": settings.WECHAT_APP_ID,
        "secret": settings.WECHAT_APP_SECRET,
        "js_code": code,
        "grant_type": "authorization_code"
    }
    
    try:
        async with httpx.AsyncClient() as client:
            response = await client.get(url, params=params)
            result = response.json()
            
            if "errcode" in result and result["errcode"] != 0:
                raise BusinessError(f"微信登录失败: {result.get('errmsg', '未知错误')}", code=500)
                
            openid = result.get("openid")
            unionid = result.get("unionid")  # 可能为None
            
            if not openid:
                raise BusinessError("无法获取openid", code=500)
                
            return openid, unionid
            
    except httpx.RequestError as e:
        raise BusinessError(f"网络请求失败: {str(e)}", code=500)
    except Exception as e:
        if isinstance(e, BusinessError):
            raise
        raise BusinessError(f"未知错误: {str(e)}", code=500)