models: Extract zerver.models.clients.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zerver/models/clients.py

@@ -0,0 +1,77 @@
+import hashlib
+from typing import Dict
+
+from django.conf import settings
+from django.db import models
+from typing_extensions import override
+
+from zerver.lib import cache
+from zerver.lib.cache import cache_with_key
+
+
+class Client(models.Model):
+    MAX_NAME_LENGTH = 30
+    name = models.CharField(max_length=MAX_NAME_LENGTH, db_index=True, unique=True)
+
+    @override
+    def __str__(self) -> str:
+        return self.name
+
+    def default_read_by_sender(self) -> bool:
+        """Used to determine whether a message was sent by a full Zulip UI
+        style client (and thus whether the message should be treated
+        as sent by a human and automatically marked as read for the
+        sender).  The purpose of this distinction is to ensure that
+        message sent to the user by e.g. a Google Calendar integration
+        using the user's own API key don't get marked as read
+        automatically.
+        """
+        sending_client = self.name.lower()
+
+        return (
+            sending_client
+            in (
+                "zulipandroid",
+                "zulipios",
+                "zulipdesktop",
+                "zulipmobile",
+                "zulipelectron",
+                "zulipterminal",
+                "snipe",
+                "website",
+                "ios",
+                "android",
+            )
+            or "desktop app" in sending_client
+            # Since the vast majority of messages are sent by humans
+            # in Zulip, treat test suite messages as such.
+            or (sending_client == "test suite" and settings.TEST_SUITE)
+        )
+
+
+get_client_cache: Dict[str, Client] = {}
+
+
+def clear_client_cache() -> None:  # nocoverage
+    global get_client_cache
+    get_client_cache = {}
+
+
+def get_client(name: str) -> Client:
+    # Accessing KEY_PREFIX through the module is necessary
+    # because we need the updated value of the variable.
+    cache_name = cache.KEY_PREFIX + name[0 : Client.MAX_NAME_LENGTH]
+    if cache_name not in get_client_cache:
+        result = get_client_remote_cache(name)
+        get_client_cache[cache_name] = result
+    return get_client_cache[cache_name]
+
+
+def get_client_cache_key(name: str) -> str:
+    return f"get_client:{hashlib.sha1(name.encode()).hexdigest()}"
+
+
+@cache_with_key(get_client_cache_key, timeout=3600 * 24 * 7)
+def get_client_remote_cache(name: str) -> Client:
+    (client, _) = Client.objects.get_or_create(name=name[0 : Client.MAX_NAME_LENGTH])
+    return client