auth: Extract handle_desktop_flow wrapper.

zerver/views/auth.py

@@ -18,6 +18,7 @@ from django.views.decorators.http import require_safe
 from django.views.generic import TemplateView
 from django.utils.translation import ugettext as _
 from django.utils.http import is_safe_url
+from functools import wraps
 import urllib
 from typing import Any, Dict, List, Optional, Mapping, cast
 
@@ -34,6 +35,7 @@ from zerver.lib.request import REQ, has_request_variables, JsonableError
 from zerver.lib.response import json_success, json_error
 from zerver.lib.sessions import set_expirable_session_var
 from zerver.lib.subdomains import get_subdomain, is_subdomain_root_or_alias
+from zerver.lib.types import ViewFuncT
 from zerver.lib.url_encoding import add_query_to_redirect_url
 from zerver.lib.user_agent import parse_user_agent
 from zerver.lib.users import get_api_key
@@ -451,12 +453,19 @@ def oauth_redirect_to_root(request: HttpRequest, url: str,
 
     return redirect(add_query_to_redirect_url(main_site_uri, urllib.parse.urlencode(params)))
 
+def handle_desktop_flow(func: ViewFuncT) -> ViewFuncT:
+    @wraps(func)
+    def wrapper(request: HttpRequest, *args: Any, **kwargs: Any) -> HttpResponse:
+        user_agent = parse_user_agent(request.META.get("HTTP_USER_AGENT", "Missing User-Agent"))
+        if user_agent["name"] == "ZulipElectron":
+            return render(request, "zerver/desktop_login.html")
+
+        return func(request, *args, **kwargs)
+    return wrapper  # type: ignore[return-value] # https://github.com/python/mypy/issues/1927
+
+@handle_desktop_flow
 def start_social_login(request: HttpRequest, backend: str, extra_arg: Optional[str]=None
                        ) -> HttpResponse:
-    user_agent = parse_user_agent(request.META.get("HTTP_USER_AGENT", "Missing User-Agent"))
-    if user_agent["name"] == "ZulipElectron":
-        return render(request, "zerver/desktop_login.html")
-
     backend_url = reverse('social:begin', args=[backend])
     extra_url_params: Dict[str, str] = {}
     if backend == "saml":