Allow Mastodon address domain to be different from primary domain

app/models/setting.rb

@@ -106,6 +106,9 @@ class Setting < RailsSettings::Base
   field :mastodon_enabled, type: :boolean,
     default: (ENV["MASTODON_PUBLIC_URL"].present?.to_s || false)
 
+  field :mastodon_address_domain, type: :string,
+    default: ENV["MASTODON_ADDRESS_DOMAIN"].presence || self.primary_domain
+
   #
   # MediaWiki
   #

app/models/user.rb

@@ -110,6 +110,11 @@ class User < ApplicationRecord
     "#{self.cn}@#{self.ou}"
   end
 
+  def mastodon_address
+    return nil unless Setting.mastodon_enabled?
+    "#{self.cn}@#{Setting.mastodon_address_domain}"
+  end
+
   def valid_attribute?(attribute_name)
     self.valid?
     self.errors[attribute_name].blank?

app/views/admin/settings/services/_mastodon.html.erb

@@ -12,5 +12,9 @@
           key: :mastodon_public_url,
           title: "Public URL"
         ) %>
+    <%= render FormElements::FieldsetResettableSettingComponent.new(
+          key: :mastodon_address_domain,
+          title: "User address domain"
+        ) %>
   <% end %>
 </ul>

app/views/services/mastodon/show.html.erb

@@ -13,7 +13,7 @@
     </p>
     <p data-controller="clipboard" class="flex gap-1 sm:w-2/5">
       <input type="text" id="user_address" class="grow"
-             value=<%= current_user.address %> disabled="disabled"
+             value=<%= current_user.mastodon_address %> disabled="disabled"
              data-clipboard-target="source" />
       <button id="copy-user-address" class="btn-md btn-icon btn-outline shrink-0"
               data-clipboard-target="trigger" data-action="clipboard#copy"

spec/models/user_spec.rb

@@ -12,6 +12,38 @@ RSpec.describe User, type: :model do
     end
   end
 
+  describe "#mastodon_address" do
+    let(:user) { build :user, cn: "jimmy", ou: "kosmos.org" }
+
+    context "Mastodon service not configured" do
+      it "returns nil" do
+        expect(user.mastodon_address).to be_nil
+      end
+    end
+
+    context "Mastodon service configured" do
+      before do
+        Setting.mastodon_enabled = true
+      end
+
+      describe "domain is the same as primary domain" do
+        it "returns the user address" do
+          expect(user.mastodon_address).to eq("jimmy@kosmos.org")
+        end
+      end
+
+      describe "domain is different from primary domain" do
+        before do
+          Setting.mastodon_address_domain = "kosmos.social"
+        end
+
+        it "returns the user address" do
+          expect(user.mastodon_address).to eq("jimmy@kosmos.social")
+        end
+      end
+    end
+  end
+
   describe "#is_admin?" do
     it "returns true when admin flag is set in LDAP" do
       expect(Devise::LDAP::Adapter).to receive(:get_ldap_param)