def get_wx_authorize_url(appid : str, state: str = None):
  if state is None:
    state = "".join([random.choice(string.ascii_letters + string.digits) for _ in range(20)])
  redirect_url = 'your callback url' # 回调链接，在这里面进行用户信息入库的操作
  response_type = 'code'
  scope = 'snsapi_userinfo'
  wx_url = f"https://open.weixin.qq.com/connect/oauth2/authorize"
  return wx_url

def request_access_token(appid : str, secret : str, code: str):
  secret = settings.WX_SECRET
  api = f"https://api.weixin.qq.com/sns/oauth2/access_token"
  r = requests.get(api)
  return r.json()

def request_userinfo(access_token: str, openid: str):
  api = f"https://api.weixin.qq.com/sns/userinfo"
  r = requests.get(api)
  return r.json()

def convert_string_encoding(s: str, from_encoding: str, to_encoding: str) -> str:
  """先根据 from_encoding 转换成bytes，然后在 decode 为 to_encoding 的字符串
  """
  return bytes(s, encoding=from_encoding).decode(to_encoding)

nickname = convert_string_encoding(resp['nickname'], 'ISO-8859-1', 'utf-8')

from app.models import WXUser, RedirectUrl
from utils import get_wx_authorize_url, get_random_string
from django.shortcuts import redirect

def login_required(func):
  def wrapper(request, *args, **kwargs):
    openid = request.openid
    try:
      user = WXUser.objects.get(openid=openid)
      request.wxuser = user
    except WXUser.DoesNotExist:
      state = get_random_string()
      redirect_url = get_wx_authorize_url(state=state)

      # 存储跳转链接
      try:
        r = RedirectUrl.objects.get(state=state)
      except RedirectUrl.DoesNotExist:
        r = RedirectUrl()
        r.state = state
      origin_url = request.get_raw_uri()
      r.url = origin_url
      r.save()

      return redirect(redirect_url)
    return func(request, *args, **kwargs)

  return wrapper

class RedirectUrl(BaseModel):
  state = models.TextField(unique=True)
  url = models.TextField()

def jwt_decode(token: Union[str, bytes]) -> tuple:
  """
  :param token : 可以是 bytes 也可以是 str，如果是 str，会先 encode 转成 bytes
  :return: 第一个参数为 payload，第二个参数为异常类型
  """
  if isinstance(token, str):
    token = token.encode()
  secret = settings.JWT_SECRET
  try:
    return jwt.decode(token, secret, algorithms=["HS256"]), None
  except Exception as e:
    # 统一捕捉异常：
    # jwt.exceptions.DecodeError
    # jwt.exceptions.InvalidSignatureError
    # jwt.exceptions.ExpiredSignatureError
    return None, e


class JWTAuthMiddleware(object):
  """
  小程序认证中间件
  """

  def __init__(self, get_response=None):
    self.get_response = get_response

  def __call__(self, request, *args, **kws):
    token = self.get_authorization_header(request)

    payload, error = jwt_decode(token)
    if not error:
      openid = payload['openid']
      request.openid = openid
    else:
      request.openid = None

    response = self.get_response(request, *args, **kws)
    return response

  def get_authorization_header(self, request):
    """
    从 AUTHORIZATION 请求头或者cookie 中获取 jwt code
    cookie 的 jwt code 的 key 为 jwtcode
    :param request:
    :return: rawtoken
    """

    auth_header = request.META.get('HTTP_AUTHORIZATION', '')
    cookie = request.COOKIES

    rawtoken = None
    if auth_header != "":
      try:
        rawtoken = auth_header.split(" ")[1]
      except IndexError as e:
        pass
    if 'jwttoken' in cookie:
      rawtoken = cookie['jwttoken']
    return rawtoken