settings: Add function to check permission for anonymous setting group.

web/src/state_data.ts

@@ -126,6 +126,15 @@ export const server_emoji_schema = z.object({
 
 export const realm_emoji_map_schema = z.record(server_emoji_schema);
 
+export const anonymous_group_type = z.object({
+    direct_subgroups: z.array(z.number()),
+    direct_members: z.array(z.number()),
+});
+
+export const group_setting_type_schema = z.union([z.number(), anonymous_group_type]);
+
+export type GroupSettingType = z.infer<typeof group_setting_type_schema>;
+
 export const user_group_schema = z.object({
     description: z.string(),
     id: z.number(),

web/src/user_groups.ts

@@ -7,7 +7,7 @@ import * as group_permission_settings from "./group_permission_settings";
 import {$t} from "./i18n";
 import {page_params} from "./page_params";
 import * as settings_config from "./settings_config";
-import type {StateData, user_group_schema} from "./state_data";
+import type {GroupSettingType, StateData, user_group_schema} from "./state_data";
 import {current_user} from "./state_data";
 import type {UserOrMention} from "./typeahead_helper";
 import type {UserGroupUpdateEvent} from "./types";
@@ -286,6 +286,28 @@ export function is_user_in_group(user_group_id: number, user_id: number): boolea
     return false;
 }
 
+export function is_user_in_setting_group(
+    setting_group: GroupSettingType,
+    user_id: number,
+): boolean {
+    if (typeof setting_group === "number") {
+        return is_user_in_group(setting_group, user_id);
+    }
+
+    const direct_members = setting_group.direct_members;
+    if (direct_members.includes(user_id)) {
+        return true;
+    }
+
+    const direct_subgroups = setting_group.direct_subgroups;
+    for (const direct_subgroup_id of direct_subgroups) {
+        if (is_user_in_group(direct_subgroup_id, user_id)) {
+            return true;
+        }
+    }
+    return false;
+}
+
 function get_display_name_for_system_group_option(setting_name: string, name: string): string {
     // We use a special label for the "Nobody" system group for clarity.
     if (setting_name === "direct_message_permission_group" && name === "Nobody") {

web/tests/user_groups.test.js

@@ -307,6 +307,25 @@ run_test("is_user_in_group", () => {
     assert.equal(user_groups.is_user_in_group(foo.id, 6), true);
     assert.equal(user_groups.is_user_in_group(foo.id, 3), false);
 
+    assert.equal(user_groups.is_user_in_setting_group(test.id, 4), true);
+    assert.equal(user_groups.is_user_in_setting_group(test.id, 1), true);
+    assert.equal(user_groups.is_user_in_setting_group(test.id, 6), true);
+    assert.equal(user_groups.is_user_in_setting_group(test.id, 3), false);
+
+    const anonymous_setting_group = {
+        direct_members: [8, 9],
+        direct_subgroups: [admins.id, test.id],
+    };
+    assert.equal(user_groups.is_user_in_setting_group(anonymous_setting_group, 8), true);
+    assert.equal(user_groups.is_user_in_setting_group(anonymous_setting_group, 9), true);
+    assert.equal(user_groups.is_user_in_setting_group(anonymous_setting_group, 10), false);
+
+    assert.equal(user_groups.is_user_in_setting_group(anonymous_setting_group, 1), true);
+    assert.equal(user_groups.is_user_in_setting_group(anonymous_setting_group, 4), true);
+    assert.equal(user_groups.is_user_in_setting_group(anonymous_setting_group, 6), true);
+    assert.equal(user_groups.is_user_in_setting_group(anonymous_setting_group, 2), false);
+    assert.equal(user_groups.is_user_in_setting_group(anonymous_setting_group, 3), false);
+
     blueslip.expect("error", "Could not find user group");
     assert.equal(user_groups.is_user_in_group(1111, 3), false);