AO3-5610 notify users when a bookmark or series they have created is hidden

app/mailers/user_mailer.rb

@@ -377,6 +377,18 @@ def admin_deleted_work_notification(user, work)
     end
   end
 
+  def admin_hidden_series_notification(creation_id, user_id)
+    @user = User.find_by(id: user_id)
+    @series = Series.find_by(id: creation_id)
+
+    I18n.with_locale(@user.preference.locale.iso) do
+      mail(
+        to: @user.email,
+        subject: default_i18n_subject(app_name: ArchiveConfig.APP_SHORT_NAME)
+      )
+    end
+  end
+
   # Sends email to creators when a creation is hidden by an admin
   def admin_hidden_work_notification(creation_id, user_id)
     @user = User.find_by(id: user_id)

app/models/series.rb

@@ -22,6 +22,8 @@
     maximum: ArchiveConfig.TITLE_MAX,
     too_long: ts("must be less than %{max} letters long.", max: ArchiveConfig.TITLE_MAX)
 
+  after_update :admin_hidden_series_notification, if: :hidden_by_admin_changed?
+
   # return title.html_safe to overcome escaping done by sanitiser
   def title
     read_attribute(:title).try(:html_safe)
@@ -304,4 +306,13 @@
   def work_types
     works.map(&:work_types).flatten.uniq
   end
+
+  private
+
+  def admin_hidden_series_notification
+    return unless hidden_by_admin?
+    users.each do |user|
+      UserMailer.send_series_hidden_notification(id, user.id).deliver_later
+    end
+  end
 end

app/views/user_mailer/admin_hidden_series_notification.html.erb

@@ -0,0 +1,14 @@
+<% content_for :message do %>
+  <p><%= t("mailer.general.greeting.formal", name: style_bold(@user.login)).html_safe %></p>
+
+  <p><%= t(".html.hidden", title: style_creation_link(@series.title, @series)).html_safe %></p>
+
+  <p><%= t(".access") %></p>
+
+  <p><%= t(".check_email") %></p>
+
+  <p><%= t(".html.tos_violation", tos_link: tos_link(t ".tos")).html_safe %></p>
+
+  <p><%= t(".html.help", contact_abuse_link: abuse_link(t ".contact_abuse")).html_safe %></p>
+<% end %>
+

app/views/user_mailer/admin_hidden_series_notification.text.erb

@@ -0,0 +1,14 @@
+<% content_for :message do %>
+<%= t("mailer.general.greeting.formal", name: @user.login) %>
+
+<%= t(".text.hidden", title: @series.title, series_url: series_url(@series)) %>
+
+<%= t(".access") %>
+
+<%= t(".check_email") %>
+
+<%= t(".text.tos_violation", tos_url: tos_url) %>
+
+<%= t(".text.help", contact_abuse_url: new_abuse_report_url) %>
+<% end %>
+