FEATURE: warn if attempting to mention a group with too many members

app/assets/javascripts/discourse/components/composer-editor.js.es6

@@ -363,7 +363,7 @@ export default Ember.Component.extend({
         const $e = $(e);
         var name = $e.data('name');
         if (found.indexOf(name) === -1){
-          this.sendAction('groupsMentioned', [{name: name, user_count: $e.data('mentionable-user-count')}]);
+          this.sendAction('groupsMentioned', [{name: name, user_count: $e.data('mentionable-user-count'), max_mentions: $e.data('max-mentions')}]);
           found.push(name);
         }
       });

app/assets/javascripts/discourse/controllers/composer.js.es6

@@ -378,11 +378,21 @@ export default Ember.Controller.extend({
     groupsMentioned(groups) {
       if (!this.get('model.creatingPrivateMessage') && !this.get('model.topic.isPrivateMessage')) {
         groups.forEach(group => {
-          const body = I18n.t('composer.group_mentioned', {
-            group: "@" + group.name,
-            count: group.user_count,
-            group_link: Discourse.getURL(`/groups/${group.name}/members`)
-          });
+          let body;
+
+          if (group.max_mentions < group.user_count) {
+            body = I18n.t('composer.group_mentioned_limit', {
+              group: "@" + group.name,
+              max: group.max_mentions,
+              group_link: Discourse.getURL(`/groups/${group.name}/members`)
+            });
+          } else {
+            body = I18n.t('composer.group_mentioned', {
+              group: "@" + group.name,
+              count: group.user_count,
+              group_link: Discourse.getURL(`/groups/${group.name}/members`)
+            });
+          }
 
           this.appEvents.trigger('composer-messages:create', {
             extraClass: 'custom-body',

app/assets/javascripts/discourse/lib/link-mentions.js.es6

@@ -2,13 +2,15 @@ import { ajax } from 'discourse/lib/ajax';
 import { userPath } from 'discourse/lib/url';
 import { formatUsername } from 'discourse/lib/utilities';
 
+let maxGroupMention;
+
 function replaceSpan($e, username, opts) {
   let extra = "";
   let extraClass = "";
 
   if (opts && opts.group) {
     if (opts.mentionable) {
-      extra = `data-name='${username}' data-mentionable-user-count='${opts.mentionable.user_count}'`;
+      extra = `data-name='${username}' data-mentionable-user-count='${opts.mentionable.user_count}' data-max-mentions='${maxGroupMention}'`;
       extraClass = "notify";
     }
     $e.replaceWith(`<a href='${Discourse.getURL("/groups/") + username}' class='mention-group ${extraClass}' ${extra}>@${username}</a>`);
@@ -61,6 +63,7 @@ export function fetchUnseenMentions(usernames, topic_id) {
     r.valid_groups.forEach(vg => foundGroups[vg] = true);
     r.mentionable_groups.forEach(mg => mentionableGroups[mg.name] = mg);
     r.cannot_see.forEach(cs => cannotSee[cs] = true);
+    maxGroupMention = r.max_users_notified_per_group_mention;
     usernames.forEach(u => checked[u] = true);
     return r;
   });

app/controllers/users_controller.rb

@@ -248,7 +248,12 @@ class UsersController < ApplicationController
         Group.mentionable(current_user)
           .where(name: usernames)
           .pluck(:name, :user_count)
-          .map { |name, user_count| { name: name, user_count: user_count } }
+          .map do |name, user_count|
+          {
+            name: name,
+            user_count: user_count
+          }
+        end
       end
 
     usernames -= groups
@@ -267,7 +272,13 @@ class UsersController < ApplicationController
       .where(username_lower: usernames)
       .pluck(:username_lower)
 
-    render json: { valid: result, valid_groups: groups, mentionable_groups: mentionable_groups, cannot_see: cannot_see }
+    render json: {
+      valid: result,
+      valid_groups: groups,
+      mentionable_groups: mentionable_groups,
+      cannot_see: cannot_see,
+      max_users_notified_per_group_mention: SiteSetting.max_users_notified_per_group_mention
+    }
   end
 
   def render_available_true

config/locales/client.en.yml

@@ -1211,6 +1211,7 @@ en:
       similar_topics: "Your topic is similar to..."
       drafts_offline: "drafts offline"
 
+      group_mentioned_limit: "<b>Warning!</b> you mentioned <a href='{{group_link}}'>{{group}}</a>, however it has more members than the administrator configured limit of {{max}} users. Nobody will be notified. "
       group_mentioned:
         one: "By mentioning {{group}}, you are about to notify <a href='{{group_link}}'>1 person</a> – are you sure?"
         other: "By mentioning {{group}}, you are about to notify <a href='{{group_link}}'>{{count}} people</a> – are you sure?"