notifications: Extract zerver/lib/url_encoding.py.

Extracting this helper library will help us avoid an import loop
between notifications.py and message.py (with bugdown in between).

But in addition to that, it's a more natural model, since some of the
uses for these functions weren't part of the notifications code
anyway.

zerver/lib/bugdown/__init__.py

@@ -35,7 +35,7 @@ from zerver.lib.camo import get_camo_url
 from zerver.lib.emoji import translate_emoticons, emoticon_regex
 from zerver.lib.mention import possible_mentions, \
     possible_user_group_mentions, extract_user_group
-from zerver.lib.notifications import encode_stream
+from zerver.lib.url_encoding import encode_stream
 from zerver.lib.thumbnail import is_thumbor_enabled
 from zerver.lib.timeout import timeout, TimeoutExpired
 from zerver.lib.cache import cache_with_key, NotFoundInCache

zerver/lib/digest.py

@@ -10,9 +10,9 @@ from django.template import loader
 from django.conf import settings
 from django.utils.timezone import now as timezone_now
 
-from zerver.lib.notifications import build_message_list, encode_stream, \
-    one_click_unsubscribe_link
+from zerver.lib.notifications import build_message_list, one_click_unsubscribe_link
 from zerver.lib.send_email import send_future_email, FromAddress
+from zerver.lib.url_encoding import encode_stream
 from zerver.models import UserProfile, UserMessage, Recipient, Stream, \
     Subscription, UserActivity, get_active_streams, get_user_profile_by_id, \
     Realm

zerver/lib/notifications.py

@@ -9,6 +9,7 @@ from django.utils.translation import ugettext as _
 from zerver.decorator import statsd_increment
 from zerver.lib.send_email import send_future_email, FromAddress
 from zerver.lib.queue import queue_json_publish
+from zerver.lib.url_encoding import pm_narrow_url, stream_narrow_url, topic_narrow_url
 from zerver.models import (
     Recipient,
     ScheduledEmail,
@@ -31,7 +32,6 @@ import lxml.html
 import re
 import subprocess
 import ujson
-import urllib
 from collections import defaultdict
 import pytz
 
@@ -44,33 +44,6 @@ def one_click_unsubscribe_link(user_profile: UserProfile, email_type: str) -> st
                                     Confirmation.UNSUBSCRIBE,
                                     url_args = {'email_type': email_type})
 
-def hash_util_encode(string: str) -> str:
-    # Do the same encoding operation as hash_util.encodeHashComponent on the
-    # frontend.
-    # `safe` has a default value of "/", but we want those encoded, too.
-    return urllib.parse.quote(
-        string.encode("utf-8"), safe=b"").replace(".", "%2E").replace("%", ".")
-
-def encode_stream(stream_id: int, stream_name: str) -> str:
-    # We encode streams for urls as something like 99-Verona.
-    stream_name = stream_name.replace(' ', '-')
-    return str(stream_id) + '-' + hash_util_encode(stream_name)
-
-def pm_narrow_url(realm: Realm, participants: List[str]) -> str:
-    participants.sort()
-    base_url = "%s/#narrow/pm-with/" % (realm.uri,)
-    return base_url + hash_util_encode(",".join(participants))
-
-def stream_narrow_url(realm: Realm, stream: Stream) -> str:
-    base_url = "%s/#narrow/stream/" % (realm.uri,)
-    return base_url + encode_stream(stream.id, stream.name)
-
-def topic_narrow_url(realm: Realm, stream: Stream, topic: str) -> str:
-    base_url = "%s/#narrow/stream/" % (realm.uri,)
-    return "%s%s/topic/%s" % (base_url,
-                              encode_stream(stream.id, stream.name),
-                              hash_util_encode(topic))
-
 def relative_to_full_url(base_url: str, content: str) -> str:
     # Convert relative URLs to absolute URLs.
     fragment = lxml.html.fromstring(content)

zerver/lib/outgoing_webhook.py

@@ -15,8 +15,8 @@ from django.utils.translation import ugettext as _
 from zerver.models import Realm, UserProfile, get_user_profile_by_id, get_client, \
     GENERIC_INTERFACE, Service, SLACK_INTERFACE, email_to_domain, get_service_profile
 from zerver.lib.actions import check_send_message
-from zerver.lib.notifications import encode_stream
 from zerver.lib.queue import retry_event
+from zerver.lib.url_encoding import encode_stream
 from zerver.lib.validator import check_dict, check_string
 from zerver.decorator import JsonableError
 

zerver/lib/url_encoding.py

@@ -0,0 +1,31 @@
+import urllib
+from typing import List
+
+from zerver.models import Realm, Stream
+
+def hash_util_encode(string: str) -> str:
+    # Do the same encoding operation as hash_util.encodeHashComponent on the
+    # frontend.
+    # `safe` has a default value of "/", but we want those encoded, too.
+    return urllib.parse.quote(
+        string.encode("utf-8"), safe=b"").replace(".", "%2E").replace("%", ".")
+
+def encode_stream(stream_id: int, stream_name: str) -> str:
+    # We encode streams for urls as something like 99-Verona.
+    stream_name = stream_name.replace(' ', '-')
+    return str(stream_id) + '-' + hash_util_encode(stream_name)
+
+def pm_narrow_url(realm: Realm, participants: List[str]) -> str:
+    participants.sort()
+    base_url = "%s/#narrow/pm-with/" % (realm.uri,)
+    return base_url + hash_util_encode(",".join(participants))
+
+def stream_narrow_url(realm: Realm, stream: Stream) -> str:
+    base_url = "%s/#narrow/stream/" % (realm.uri,)
+    return base_url + encode_stream(stream.id, stream.name)
+
+def topic_narrow_url(realm: Realm, stream: Stream, topic: str) -> str:
+    base_url = "%s/#narrow/stream/" % (realm.uri,)
+    return "%s%s/topic/%s" % (base_url,
+                              encode_stream(stream.id, stream.name),
+                              hash_util_encode(topic))