settings_data: Add 'user_can_create_streams' helper.

This commit adds 'user_can_create_streams' helper which is
used to check whether user can create streams or not and
replaces all the instances of 'page_params.can_create_streams'.

This change helps us to remove the complex logic of updating
'page_params.can_create_streams' for 'realm_update' event in
'server_events_dispatch.js', as we will always get the updated
values from the added helper for checking whether the users can
create streams or not.

frontend_tests/node_tests/hotkey.js

@@ -13,7 +13,6 @@ const {
 const {make_stub} = require("../zjsunit/stub");
 const {run_test} = require("../zjsunit/test");
 const $ = require("../zjsunit/zjquery");
-const {page_params} = require("../zjsunit/zpage_params");
 
 // Important note on these tests:
 
@@ -74,6 +73,7 @@ const popovers = mock_esm("../../static/js/popovers", {
 });
 const reactions = mock_esm("../../static/js/reactions");
 const search = mock_esm("../../static/js/search");
+const settings_data = mock_esm("../../static/js/settings_data");
 const stream_list = mock_esm("../../static/js/stream_list");
 const subs = mock_esm("../../static/js/subs");
 
@@ -281,13 +281,13 @@ run_test("allow normal typing when processing text", (override) => {
 });
 
 run_test("streams", (override) => {
-    page_params.can_create_streams = true;
+    settings_data.user_can_create_streams = () => true;
     override(overlays, "streams_open", () => true);
     override(overlays, "is_active", () => true);
     assert_mapping("S", subs, "keyboard_sub");
     assert_mapping("V", subs, "view_stream");
     assert_mapping("n", subs, "open_create_stream");
-    page_params.can_create_streams = false;
+    settings_data.user_can_create_streams = () => false;
     assert_unmapped("n");
 });
 

frontend_tests/node_tests/settings_data.js

@@ -167,3 +167,33 @@ run_test("user_can_subscribe_other_users", () => {
     isaac.date_joined = new Date(Date.now() - 20 * 86400000);
     assert.equal(can_subscribe_other_users(), true);
 });
+
+run_test("user_can_create_streams", () => {
+    const can_create_streams = settings_data.user_can_create_streams;
+
+    page_params.is_admin = true;
+    page_params.realm_create_stream_policy =
+        settings_config.common_policy_values.by_admins_only.code;
+    assert.equal(can_create_streams(), true);
+
+    page_params.is_admin = false;
+    assert.equal(can_create_streams(), false);
+
+    page_params.is_guest = true;
+    page_params.realm_create_stream_policy = settings_config.common_policy_values.by_members.code;
+    assert.equal(can_create_streams(), false);
+
+    page_params.is_guest = false;
+    assert.equal(can_create_streams(), true);
+
+    page_params.realm_create_stream_policy =
+        settings_config.common_policy_values.by_full_members.code;
+    page_params.user_id = 30;
+    people.add_active_user(isaac);
+    isaac.date_joined = new Date(Date.now());
+    page_params.realm_waiting_period_threshold = 10;
+    assert.equal(can_create_streams(), false);
+
+    isaac.date_joined = new Date(Date.now() - 20 * 86400000);
+    assert.equal(can_create_streams(), true);
+});

static/js/hotkey.js

@@ -32,6 +32,7 @@ import * as popovers from "./popovers";
 import * as reactions from "./reactions";
 import * as recent_topics from "./recent_topics";
 import * as search from "./search";
+import * as settings_data from "./settings_data";
 import * as stream_list from "./stream_list";
 import * as stream_popover from "./stream_popover";
 import * as subs from "./subs";
@@ -724,7 +725,11 @@ export function process_hotkey(e, hotkey) {
             subs.view_stream();
             return true;
         }
-        if (event_name === "n_key" && overlays.streams_open() && page_params.can_create_streams) {
+        if (
+            event_name === "n_key" &&
+            overlays.streams_open() &&
+            settings_data.user_can_create_streams()
+        ) {
             subs.open_create_stream();
             return true;
         }

static/js/server_events_dispatch.js

@@ -221,12 +221,6 @@ export function dispatch_normal_event(event) {
                         page_params["realm_" + event.property] = event.value;
                         realm_settings[event.property]();
                         settings_org.sync_realm_settings(event.property);
-                        if (event.property === "create_stream_policy") {
-                            // TODO: Add waiting_period_threshold logic here.
-                            page_params.can_create_streams =
-                                page_params.is_admin ||
-                                page_params.realm_create_stream_policy === 1;
-                        }
 
                         if (event.property === "name" && window.electron_bridge !== undefined) {
                             window.electron_bridge.send_event("realm_name", event.value);

static/js/settings_data.js

@@ -114,3 +114,7 @@ export function user_can_invite_others_to_realm() {
 export function user_can_subscribe_other_users() {
     return user_has_permission(page_params.realm_invite_to_stream_policy);
 }
+
+export function user_can_create_streams() {
+    return user_has_permission(page_params.realm_create_stream_policy);
+}

static/js/subs.js

@@ -24,6 +24,7 @@ import {page_params} from "./page_params";
 import * as people from "./people";
 import * as scroll_util from "./scroll_util";
 import * as search_util from "./search_util";
+import * as settings_data from "./settings_data";
 import * as stream_create from "./stream_create";
 import * as stream_data from "./stream_data";
 import * as stream_edit from "./stream_edit";
@@ -626,7 +627,7 @@ export function setup_page(callback) {
         $("#subscriptions_table").empty();
 
         const template_data = {
-            can_create_streams: page_params.can_create_streams,
+            can_create_streams: settings_data.user_can_create_streams(),
             hide_all_streams: !should_list_all_streams(),
             max_name_length: page_params.max_stream_name_length,
             max_description_length: page_params.max_stream_description_length,