from __future__ import annotations

import time

import httpx

from .config import Settings, get_settings


class WechatConfigError(RuntimeError):
    pass


class WechatApiError(RuntimeError):
    pass


_access_token_cache: dict[str, object] = {"appid": None, "token": None, "expires_at": 0.0}


def _require_miniapp_settings(settings: Settings) -> tuple[str, str]:
    if not settings.wechat_miniapp_appid or not settings.wechat_miniapp_secret:
        raise WechatConfigError("微信小程序登录未配置")
    return settings.wechat_miniapp_appid, settings.wechat_miniapp_secret


def _wechat_json(response: httpx.Response) -> dict:
    try:
        return response.json()
    except ValueError as exc:
        raise WechatApiError("微信登录服务返回异常") from exc


def get_access_token(settings: Settings | None = None) -> str:
    settings = settings or get_settings()
    appid, secret = _require_miniapp_settings(settings)
    now = time.time()
    cached_token = _access_token_cache.get("token")
    if _access_token_cache.get("appid") == appid and isinstance(cached_token, str) and now < float(_access_token_cache.get("expires_at", 0)):
        return cached_token

    try:
        response = httpx.get(
            "https://api.weixin.qq.com/cgi-bin/token",
            params={"grant_type": "client_credential", "appid": appid, "secret": secret},
            timeout=8,
        )
    except httpx.HTTPError as exc:
        raise WechatApiError("微信登录服务暂时不可用") from exc

    data = _wechat_json(response)
    token = data.get("access_token")
    if not isinstance(token, str) or not token:
        raise WechatApiError("微信登录服务暂时不可用")
    expires_in = data.get("expires_in")
    ttl = int(expires_in) if isinstance(expires_in, int | str) and str(expires_in).isdigit() else 7200
    _access_token_cache.update({"appid": appid, "token": token, "expires_at": now + max(ttl - 300, 60)})
    return token


def exchange_phone_code(code: str, settings: Settings | None = None) -> str:
    access_token = get_access_token(settings)
    try:
        response = httpx.post(
            "https://api.weixin.qq.com/wxa/business/getuserphonenumber",
            params={"access_token": access_token},
            json={"code": code},
            timeout=8,
        )
    except httpx.HTTPError as exc:
        raise WechatApiError("手机号授权服务暂时不可用") from exc

    data = _wechat_json(response)
    if data.get("errcode", 0) != 0:
        raise WechatApiError("手机号授权失败，请重试")
    phone_info = data.get("phone_info")
    if not isinstance(phone_info, dict):
        raise WechatApiError("手机号授权服务返回异常")
    phone_number = phone_info.get("phoneNumber") or phone_info.get("purePhoneNumber")
    if not isinstance(phone_number, str) or not phone_number.strip():
        raise WechatApiError("手机号授权服务返回异常")
    return phone_number.strip()