page_params: Add community_topic_editing_limit_seconds.

This was previously hardcoded with agreement between the Zulip backend
and frontend as 86400 seconds (1 day).  Now, it's still hardcoded in
the backend, but arranged in a way where we could add a setting
without any changes to the mobile and terminal apps to update logic.

Fixes #15278.

frontend_tests/node_tests/message_edit.js

@@ -1,5 +1,7 @@
 set_global('document', null);
-set_global('page_params', {});
+set_global('page_params', {
+    realm_community_topic_editing_limit_seconds: 86400,
+});
 
 global.stub_out_jquery();
 
@@ -75,6 +77,7 @@ run_test('get_editability', () => {
         realm_allow_community_topic_editing: true,
         realm_allow_message_editing: true,
         realm_message_content_edit_limit_seconds: 0,
+        realm_community_topic_editing_limit_seconds: 86400,
         is_admin: false,
     };
     message.timestamp = current_timestamp - 60;

static/js/message_edit.js

@@ -47,9 +47,9 @@ function is_topic_editable(message, edit_limit_seconds_buffer) {
     }
 
     // If you're using community topic editing, there's a deadline.
-    // TODO: Change hardcoded value (24 hrs) to be realm setting.  Currently, it is
-    // DEFAULT_COMMUNITY_TOPIC_EDITING_LIMIT_SECONDS
-    return 86400 + edit_limit_seconds_buffer + now.diffSeconds(message.timestamp * 1000) > 0;
+    return page_params.realm_community_topic_editing_limit_seconds
+        + edit_limit_seconds_buffer
+        + now.diffSeconds(message.timestamp * 1000) > 0;
 }
 
 function get_editability(message, edit_limit_seconds_buffer) {

templates/zerver/api/changelog.md

@@ -10,6 +10,13 @@ below features are supported.
 
 ## Changes in Zulip 2.2
 
+**Feature level 11**
+
+* [`POST /register`](/api/register-queue): Added
+  `realm_community_topic_editing_limit_seconds` to the response, the
+  time limit before community topic editing is forbidden.  A `null`
+  value means no limit.
+
 **Feature level 10**
 
 * [`GET users/me`](/api/get-profile): Added `avatar_version`, `is_guest`,

zerver/lib/events.py

@@ -147,6 +147,8 @@ def fetch_initial_state_data(user_profile: UserProfile,
         state['realm_allow_message_deleting'] = realm.allow_message_deleting
         state['realm_message_content_edit_limit_seconds'] = realm.message_content_edit_limit_seconds
         state['realm_message_content_delete_limit_seconds'] = realm.message_content_delete_limit_seconds
+        state['realm_community_topic_editing_limit_seconds'] = \
+            Realm.DEFAULT_COMMUNITY_TOPIC_EDITING_LIMIT_SECONDS
         state['realm_icon_url'] = realm_icon_url(realm)
         state['realm_icon_source'] = realm.icon_source
         state['max_icon_file_size'] = settings.MAX_ICON_FILE_SIZE

zerver/tests/test_home.py

@@ -134,6 +134,7 @@ class HomeTest(ZulipTestCase):
             "realm_bot_creation_policy",
             "realm_bot_domain",
             "realm_bots",
+            "realm_community_topic_editing_limit_seconds",
             "realm_create_stream_policy",
             "realm_default_code_block_language",
             "realm_default_external_accounts",