from collections.abc import Mapping
from typing import Any

from ..api_config import APIEndpointRegistry
from ..request import APIClient, APIClientError, APIResponseFormatError


class APIAdapterError(APIClientError):
    """Adapter 层的结构化异常。"""


class APIBusinessError(APIAdapterError):
    """HTTP 请求成功，但上游接口返回业务错误。"""

    def __init__(
        self,
        message: str,
        *,
        endpoint: str,
        code: Any = None,
    ):
        super().__init__(message)
        self.endpoint = endpoint
        self.code = code


class EndpointAdapter:
    """把端点配置转换为 HTTP 请求；子类只处理各上游的协议差异。"""

    def __init__(self, client: APIClient, registry: APIEndpointRegistry):
        self._client = client
        self._registry = registry

    async def request(
        self,
        endpoint_name: str,
        *,
        params: Mapping[str, Any] | None = None,
        out_key: str | None = "data",
        path_params: Mapping[str, Any] | None = None,
    ) -> Any:
        endpoint = self._registry.get(endpoint_name)
        request_params = self.prepare_params(endpoint, params)
        url = self._registry.resolve(endpoint_name, path_params)
        configured_method = str(endpoint.get("method", "GET")).upper()

        if configured_method == "POST":
            payload = await self._client.post(
                url,
                data=request_params,
                retry=bool(endpoint.get("retry", False)),
            )
        else:
            payload = await self._client.get(
                url,
                params=request_params,
                retry=bool(endpoint.get("retry", True)),
            )

        payload = self.validate_payload(endpoint_name, payload)
        return self.extract_payload(payload, out_key)

    def prepare_params(
        self,
        endpoint: Mapping[str, Any],
        params: Mapping[str, Any] | None,
    ) -> dict[str, Any]:
        request_params = dict(endpoint.get("params", {}))
        if params:
            request_params.update(params)
        return request_params

    def validate_payload(self, endpoint_name: str, payload: Any) -> Any:
        return payload

    def extract_payload(self, payload: Any, out_key: str | None) -> Any:
        if out_key in (None, ""):
            return payload
        if isinstance(payload, bytes):
            raise APIResponseFormatError("二进制响应无法提取 JSON 字段")
        if not isinstance(payload, Mapping):
            raise APIResponseFormatError(f"响应不是对象，无法提取字段: {out_key}")
        if out_key not in payload:
            raise APIResponseFormatError(f"响应缺少字段: {out_key}")
        return payload[out_key]