Initial work to add notification reason to emails

Adds `#build_notification_recipients` to `NotificationRecipientService`
that returns the `NotificationRecipient` objects in order to be able to
access the new attribute `reason`.

This new attribute is used in the different notifier methods in order to
add the reason as a header: `X-GitLab-NotificationReason`.

Only the reason with the most priority gets sent.

1 files changed, 16 insertions, 0 deletions

diff --git a/app/helpers/emails_helper.rb b/app/helpers/emails_helper.rb
index 878bc9b5c9c..4ddc1dbed49 100644
--- a/app/helpers/emails_helper.rb
+++ b/app/helpers/emails_helper.rb
@@ -80,4 +80,20 @@ module EmailsHelper
       'text-align:center'
     ].join(';')
   end
+
+  # "You are receiving this email because #{reason}"
+  def notification_reason_text(reason)
+    string = case reason
+             when NotificationReason::OWN_ACTIVITY
+               'of your activity'
+             when NotificationReason::ASSIGNED
+               'you have been assigned an item'
+             when NotificationReason::MENTIONED
+               'you have been mentioned'
+             else
+               'of your account'
+             end
+
+    "#{string} on #{Gitlab.config.gitlab.host}"
+  end
 end