# unipay/core.py
from abc import ABC, abstractmethod
from typing import Any, Dict

class GatewayError(Exception):
    pass

class Gateway(ABC):
    """
    抽象统一支付网关接口。
    实现应异步（aiohttp）。
    """

    @abstractmethod
    async def create_payment(self, payload: Dict[str, Any]) -> Dict[str, Any]:
        """
        创建支付订单。
        payload 包含：amount, currency, subject/description, return_url, notify_url, customer/context 等
        返回标准字典，包含至少：{"provider":"wechat|alipay|paypal|stripe", "data": {...}}
        """
        raise NotImplementedError

    @abstractmethod
    async def refund(self, payload: Dict[str, Any]) -> Dict[str, Any]:
        """
        发起退款。
        payload 内常见字段：out_trade_no, out_refund_no, amount, total_amount, reason
        """
        raise NotImplementedError

    @abstractmethod
    async def query(self, payload: Dict[str, Any]) -> Dict[str, Any]:
        """
        查询订单或退款状态。
        """
        raise NotImplementedError

    @abstractmethod
    async def handle_notify(self, headers: Dict[str,str], body: str) -> Dict[str, Any]:
        """
        验签并解密回调，返回解密后的标准 dict（包括 out_trade_no, status, attach 等）
        """
        raise NotImplementedError