zilencer: Tighten type annotations of views.

`remote_server_path` allows us to get rid of all the `validate_entity`
calls in `zilencer.views` and remove all the `Union` type annotations
in the signatures of the authenticated view functions.

Signed-off-by: Zixuan James Li <p359101898@gmail.com>

zilencer/views.py

@@ -1,6 +1,6 @@
 import datetime
 import logging
-from typing import Any, Dict, List, Optional, Type, TypeVar, Union
+from typing import Any, Dict, List, Optional, Type, TypeVar
 from uuid import UUID
 
 from django.core.exceptions import ValidationError
@@ -36,7 +36,6 @@ from zerver.lib.validator import (
     check_string,
     check_string_fixed_length,
 )
-from zerver.models import UserProfile
 from zerver.views.push_notifications import validate_token
 from zilencer.auth import InvalidZulipServerKeyError
 from zilencer.models import (
@@ -51,12 +50,6 @@ from zilencer.models import (
 logger = logging.getLogger(__name__)
 
 
-def validate_entity(entity: Union[UserProfile, RemoteZulipServer]) -> RemoteZulipServer:
-    if not isinstance(entity, RemoteZulipServer):
-        raise JsonableError(err_("Must validate with valid Zulip server API key"))
-    return entity
-
-
 def validate_uuid(uuid: str) -> None:
     try:
         uuid_object = UUID(uuid, version=4)
@@ -70,14 +63,10 @@ def validate_uuid(uuid: str) -> None:
         raise ValidationError(err_("Invalid UUID"))
 
 
-def validate_bouncer_token_request(
-    entity: Union[UserProfile, RemoteZulipServer], token: str, kind: int
-) -> RemoteZulipServer:
+def validate_bouncer_token_request(token: str, kind: int) -> None:
     if kind not in [RemotePushDeviceToken.APNS, RemotePushDeviceToken.GCM]:
         raise JsonableError(err_("Invalid token type"))
-    server = validate_entity(entity)
     validate_token(token, kind)
-    return server
 
 
 @csrf_exempt
@@ -156,14 +145,14 @@ def register_remote_server(
 @has_request_variables
 def register_remote_push_device(
     request: HttpRequest,
-    entity: Union[UserProfile, RemoteZulipServer],
+    server: RemoteZulipServer,
     user_id: Optional[int] = REQ(json_validator=check_int, default=None),
     user_uuid: Optional[str] = REQ(default=None),
     token: str = REQ(),
     token_kind: int = REQ(json_validator=check_int),
     ios_app_id: Optional[str] = None,
 ) -> HttpResponse:
-    server = validate_bouncer_token_request(entity, token, token_kind)
+    validate_bouncer_token_request(token, token_kind)
 
     if user_id is None and user_uuid is None:
         raise JsonableError(_("Missing user_id or user_uuid"))
@@ -195,14 +184,14 @@ def register_remote_push_device(
 @has_request_variables
 def unregister_remote_push_device(
     request: HttpRequest,
-    entity: Union[UserProfile, RemoteZulipServer],
+    server: RemoteZulipServer,
     token: str = REQ(),
     token_kind: int = REQ(json_validator=check_int),
     user_id: Optional[int] = REQ(json_validator=check_int, default=None),
     user_uuid: Optional[str] = REQ(default=None),
     ios_app_id: Optional[str] = None,
 ) -> HttpResponse:
-    server = validate_bouncer_token_request(entity, token, token_kind)
+    validate_bouncer_token_request(token, token_kind)
     user_identity = UserPushIndentityCompat(user_id=user_id, user_uuid=user_uuid)
 
     deleted = RemotePushDeviceToken.objects.filter(
@@ -217,11 +206,10 @@ def unregister_remote_push_device(
 @has_request_variables
 def unregister_all_remote_push_devices(
     request: HttpRequest,
-    entity: Union[UserProfile, RemoteZulipServer],
+    server: RemoteZulipServer,
     user_id: Optional[int] = REQ(json_validator=check_int, default=None),
     user_uuid: Optional[str] = REQ(default=None),
 ) -> HttpResponse:
-    server = validate_entity(entity)
     user_identity = UserPushIndentityCompat(user_id=user_id, user_uuid=user_uuid)
 
     RemotePushDeviceToken.objects.filter(user_identity.filter_q(), server=server).delete()
@@ -231,11 +219,9 @@ def unregister_all_remote_push_devices(
 @has_request_variables
 def remote_server_notify_push(
     request: HttpRequest,
-    entity: Union[UserProfile, RemoteZulipServer],
+    server: RemoteZulipServer,
     payload: Dict[str, Any] = REQ(argument_type="body"),
 ) -> HttpResponse:
-    server = validate_entity(entity)
-
     user_identity = UserPushIndentityCompat(payload.get("user_id"), payload.get("user_uuid"))
 
     gcm_payload = payload["gcm_payload"]
@@ -343,7 +329,7 @@ def batch_create_table_data(
 @has_request_variables
 def remote_server_post_analytics(
     request: HttpRequest,
-    entity: Union[UserProfile, RemoteZulipServer],
+    server: RemoteZulipServer,
     realm_counts: List[Dict[str, Any]] = REQ(
         json_validator=check_list(
             check_dict_only(
@@ -387,8 +373,6 @@ def remote_server_post_analytics(
         default=None,
     ),
 ) -> HttpResponse:
-    server = validate_entity(entity)
-
     validate_incoming_table_data(server, RemoteRealmCount, realm_counts, True)
     validate_incoming_table_data(server, RemoteInstallationCount, installation_counts, True)
     if realmauditlog_rows is not None:
@@ -449,11 +433,7 @@ def get_last_id_from_server(server: RemoteZulipServer, model: Any) -> int:
 
 
 @has_request_variables
-def remote_server_check_analytics(
-    request: HttpRequest, entity: Union[UserProfile, RemoteZulipServer]
-) -> HttpResponse:
-    server = validate_entity(entity)
-
+def remote_server_check_analytics(request: HttpRequest, server: RemoteZulipServer) -> HttpResponse:
     result = {
         "last_realm_count_id": get_last_id_from_server(server, RemoteRealmCount),
         "last_installation_count_id": get_last_id_from_server(server, RemoteInstallationCount),