Show header and footer system messages in email

* Add email_header_and_footer_enabled flag to appearances table
* Set email_header_and_footer_enabled default value to false
* Add checkbox to appearance to toggle show header and footer in emails
* Add email_header_and_footer_enabled to allowed params in controller
* Add header and footer messages to the html and text email layouts
* Remove the color styling for emails header and footer
* Add empty_mailer layout for emails without layout,
to have the header and footer applied

2 files changed, 43 insertions, 3 deletions

diff --git a/app/helpers/appearances_helper.rb b/app/helpers/appearances_helper.rb
index 023e44258b7..c0db9910143 100644
--- a/app/helpers/appearances_helper.rb
+++ b/app/helpers/appearances_helper.rb
@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 module AppearancesHelper
+  include MarkupHelper
+
   def brand_title
     current_appearance&.title.presence || default_brand_title
   end
@@ -47,7 +49,7 @@ module AppearancesHelper
     class_names = []
     class_names << 'with-performance-bar' if performance_bar_enabled?
 
-    render_message(:header_message, class_names)
+    render_message(:header_message, class_names: class_names)
   end
 
   def footer_message
@@ -58,10 +60,10 @@ module AppearancesHelper
 
   private
 
-  def render_message(field_sym, class_names = [])
+  def render_message(field_sym, class_names: [], style: message_style)
     class_names << field_sym.to_s.dasherize
 
-    content_tag :div, class: class_names, style: message_style do
+    content_tag :div, class: class_names, style: style do
       markdown_field(current_appearance, field_sym)
     end
   end
diff --git a/app/helpers/emails_helper.rb b/app/helpers/emails_helper.rb
index dedc58f482b..96471d15aac 100644
--- a/app/helpers/emails_helper.rb
+++ b/app/helpers/emails_helper.rb
@@ -131,4 +131,42 @@ module EmailsHelper
 
     project.id.to_s + "." + project_path_as_domain + "." + Gitlab.config.gitlab.host
   end
+
+  def html_header_message
+    return unless show_header?
+
+    render_message(:header_message, style: '')
+  end
+
+  def html_footer_message
+    return unless show_footer?
+
+    render_message(:footer_message, style: '')
+  end
+
+  def text_header_message
+    return unless show_header?
+
+    strip_tags(render_message(:header_message, style: ''))
+  end
+
+  def text_footer_message
+    return unless show_footer?
+
+    strip_tags(render_message(:footer_message, style: ''))
+  end
+
+  private
+
+  def show_footer?
+    email_header_and_footer_enabled? && current_appearance&.show_footer?
+  end
+
+  def show_header?
+    email_header_and_footer_enabled? && current_appearance&.show_header?
+  end
+
+  def email_header_and_footer_enabled?
+    current_appearance&.email_header_and_footer_enabled?
+  end
 end