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.

3 files changed, 38 insertions, 34 deletions

diff --git a/app/mailers/emails/issues.rb b/app/mailers/emails/issues.rb
index 64ca2d2eacf..b33131becd3 100644
--- a/app/mailers/emails/issues.rb
+++ b/app/mailers/emails/issues.rb
@@ -1,54 +1,54 @@
 module Emails
   module Issues
-    def new_issue_email(recipient_id, issue_id)
+    def new_issue_email(recipient_id, issue_id, reason = nil)
       setup_issue_mail(issue_id, recipient_id)
 
-      mail_new_thread(@issue, issue_thread_options(@issue.author_id, recipient_id))
+      mail_new_thread(@issue, issue_thread_options(@issue.author_id, recipient_id, reason))
     end
 
-    def new_mention_in_issue_email(recipient_id, issue_id, updated_by_user_id)
+    def new_mention_in_issue_email(recipient_id, issue_id, updated_by_user_id, reason = nil)
       setup_issue_mail(issue_id, recipient_id)
-      mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def reassigned_issue_email(recipient_id, issue_id, previous_assignee_ids, updated_by_user_id)
+    def reassigned_issue_email(recipient_id, issue_id, previous_assignee_ids, updated_by_user_id, reason = nil)
       setup_issue_mail(issue_id, recipient_id)
 
       @previous_assignees = []
       @previous_assignees = User.where(id: previous_assignee_ids) if previous_assignee_ids.any?
 
-      mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def closed_issue_email(recipient_id, issue_id, updated_by_user_id)
+    def closed_issue_email(recipient_id, issue_id, updated_by_user_id, reason = nil)
       setup_issue_mail(issue_id, recipient_id)
 
       @updated_by = User.find(updated_by_user_id)
-      mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def relabeled_issue_email(recipient_id, issue_id, label_names, updated_by_user_id)
+    def relabeled_issue_email(recipient_id, issue_id, label_names, updated_by_user_id, reason = nil)
       setup_issue_mail(issue_id, recipient_id)
 
       @label_names = label_names
       @labels_url = project_labels_url(@project)
-      mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def issue_status_changed_email(recipient_id, issue_id, status, updated_by_user_id)
+    def issue_status_changed_email(recipient_id, issue_id, status, updated_by_user_id, reason = nil)
       setup_issue_mail(issue_id, recipient_id)
 
       @issue_status = status
       @updated_by = User.find(updated_by_user_id)
-      mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def issue_moved_email(recipient, issue, new_issue, updated_by_user)
+    def issue_moved_email(recipient, issue, new_issue, updated_by_user, reason = nil)
       setup_issue_mail(issue.id, recipient.id)
 
       @new_issue = new_issue
       @new_project = new_issue.project
-      mail_answer_thread(issue, issue_thread_options(updated_by_user.id, recipient.id))
+      mail_answer_thread(issue, issue_thread_options(updated_by_user.id, recipient.id, reason))
     end
 
     private
@@ -61,11 +61,12 @@ module Emails
       @sent_notification = SentNotification.record(@issue, recipient_id, reply_key)
     end
 
-    def issue_thread_options(sender_id, recipient_id)
+    def issue_thread_options(sender_id, recipient_id, reason)
       {
         from: sender(sender_id),
         to: recipient(recipient_id),
-        subject: subject("#{@issue.title} (##{@issue.iid})")
+        subject: subject("#{@issue.title} (##{@issue.iid})"),
+        'X-GitLab-NotificationReason' => reason
       }
     end
   end
diff --git a/app/mailers/emails/merge_requests.rb b/app/mailers/emails/merge_requests.rb
index 3626f8ce416..5fe09cea83f 100644
--- a/app/mailers/emails/merge_requests.rb
+++ b/app/mailers/emails/merge_requests.rb
@@ -1,57 +1,57 @@
 module Emails
   module MergeRequests
-    def new_merge_request_email(recipient_id, merge_request_id)
+    def new_merge_request_email(recipient_id, merge_request_id, reason = nil)
       setup_merge_request_mail(merge_request_id, recipient_id)
 
-      mail_new_thread(@merge_request, merge_request_thread_options(@merge_request.author_id, recipient_id))
+      mail_new_thread(@merge_request, merge_request_thread_options(@merge_request.author_id, recipient_id, reason))
     end
 
-    def new_mention_in_merge_request_email(recipient_id, merge_request_id, updated_by_user_id)
+    def new_mention_in_merge_request_email(recipient_id, merge_request_id, updated_by_user_id, reason = nil)
       setup_merge_request_mail(merge_request_id, recipient_id)
-      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def reassigned_merge_request_email(recipient_id, merge_request_id, previous_assignee_id, updated_by_user_id)
+    def reassigned_merge_request_email(recipient_id, merge_request_id, previous_assignee_id, updated_by_user_id, reason = nil)
       setup_merge_request_mail(merge_request_id, recipient_id)
 
       @previous_assignee = User.find_by(id: previous_assignee_id) if previous_assignee_id
-      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def relabeled_merge_request_email(recipient_id, merge_request_id, label_names, updated_by_user_id)
+    def relabeled_merge_request_email(recipient_id, merge_request_id, label_names, updated_by_user_id, reason = nil)
       setup_merge_request_mail(merge_request_id, recipient_id)
 
       @label_names = label_names
       @labels_url = project_labels_url(@project)
-      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def closed_merge_request_email(recipient_id, merge_request_id, updated_by_user_id)
+    def closed_merge_request_email(recipient_id, merge_request_id, updated_by_user_id, reason = nil)
       setup_merge_request_mail(merge_request_id, recipient_id)
 
       @updated_by = User.find(updated_by_user_id)
-      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def merged_merge_request_email(recipient_id, merge_request_id, updated_by_user_id)
+    def merged_merge_request_email(recipient_id, merge_request_id, updated_by_user_id, reason = nil)
       setup_merge_request_mail(merge_request_id, recipient_id)
 
-      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def merge_request_status_email(recipient_id, merge_request_id, status, updated_by_user_id)
+    def merge_request_status_email(recipient_id, merge_request_id, status, updated_by_user_id, reason = nil)
       setup_merge_request_mail(merge_request_id, recipient_id)
 
       @mr_status = status
       @updated_by = User.find(updated_by_user_id)
-      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id))
+      mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
-    def resolved_all_discussions_email(recipient_id, merge_request_id, resolved_by_user_id)
+    def resolved_all_discussions_email(recipient_id, merge_request_id, resolved_by_user_id, reason = nil)
       setup_merge_request_mail(merge_request_id, recipient_id)
 
       @resolved_by = User.find(resolved_by_user_id)
-      mail_answer_thread(@merge_request, merge_request_thread_options(resolved_by_user_id, recipient_id))
+      mail_answer_thread(@merge_request, merge_request_thread_options(resolved_by_user_id, recipient_id, reason))
     end
 
     private
@@ -64,11 +64,12 @@ module Emails
       @sent_notification = SentNotification.record(@merge_request, recipient_id, reply_key)
     end
 
-    def merge_request_thread_options(sender_id, recipient_id)
+    def merge_request_thread_options(sender_id, recipient_id, reason = nil)
       {
         from: sender(sender_id),
         to: recipient(recipient_id),
-        subject: subject("#{@merge_request.title} (#{@merge_request.to_reference})")
+        subject: subject("#{@merge_request.title} (#{@merge_request.to_reference})"),
+        'X-GitLab-NotificationReason' => reason
       }
     end
   end
diff --git a/app/mailers/notify.rb b/app/mailers/notify.rb
index ec886e993c3..eade0fe278f 100644
--- a/app/mailers/notify.rb
+++ b/app/mailers/notify.rb
@@ -112,6 +112,8 @@ class Notify < BaseMailer
     headers["X-GitLab-#{model.class.name}-ID"] = model.id
     headers['X-GitLab-Reply-Key'] = reply_key
 
+    @reason = headers['X-GitLab-NotificationReason']
+
     if Gitlab::IncomingEmail.enabled? && @sent_notification
       address = Mail::Address.new(Gitlab::IncomingEmail.reply_address(reply_key))
       address.display_name = @project.name_with_namespace