Add mailer for user removed from rotation

- Html and text templates

ee/app/mailers/ee/notify.rb

@@ -13,6 +13,7 @@ module EE
       include ::Emails::Epics
       include ::Emails::Requirements
       include ::Emails::UserCap
+      include ::Emails::OncallRotation
     end
 
     attr_reader :group

ee/app/mailers/emails/oncall_rotation.rb

+# frozen_string_literal: true
+
+module Emails
+  module OncallRotation
+    extend ActiveSupport::Concern
+
+    def user_removed_from_rotation_email(user, rotation, recipients)
+      @user = user
+      @rotation = rotation
+      @schedule = rotation.schedule
+      @project = rotation.project
+
+      mail(to: recipients.map(&:email), subject: subject('User removed from On-call rotation')) do |format|
+        format.html { render layout: 'mailer' }
+        format.text { render layout: 'mailer' }
+      end
+    end
+  end
+end

ee/app/services/ee/notification_service.rb

@@ -76,8 +76,24 @@ module EE
       end
     end
 
+    def oncall_user_removed(rotation, user)
+      project_owners_and_participants(rotation, user).each do |recipient|
+        mailer.user_removed_from_rotation_email(user, rotation, [recipient]).deliver_later
+      end
+    end
+
     private
 
+    def project_owners_and_participants(rotation, user)
+      project = rotation.project
+
+      owners = project.members.owners.map(&:user).presence || [project.owner] || project.group&.owners
+
+      excluding_user = [owners, rotation.participants.map(&:user)].uniq - [user]
+
+      excluding_user.compact.flatten
+    end
+
     def add_mr_approvers_email(merge_request, approvers, current_user)
       approvers.each do |approver|
         mailer.add_merge_request_approver_email(approver.id, merge_request.id, current_user.id).deliver_later

ee/app/services/incident_management/oncall_rotations/remove_participant_service.rb

@@ -18,6 +18,7 @@ module IncidentManagement
 
         if deleted
           save_current_shift!
+          send_notification
         end
       end
 
@@ -34,6 +35,10 @@ module IncidentManagement
 
         oncall_rotation.touch
       end
+
+      def send_notification
+        NotificationService.new.oncall_user_removed(oncall_rotation, user_to_remove)
+      end
     end
   end
 end

ee/app/views/notify/user_removed_from_rotation_email.html.haml

+%p
+  = _("%{user_name} (%{user_username}) was removed from %{rotation} in %{schedule} in %{project}. ") % { user_name: @user.name, user_username: @user.username, rotation: @rotation.name, schedule: @rotation.schedule.name, project: @project.name }
+
+%p
+  = html_escape(_("%{rotation} has been recalculated with the remaining participants. Please review the new setup for %{rotation_link}. It is recommended that you reach out to the current on-call responder to ensure continuity of on-call coverage.")) % { rotation: @rotation.name, rotation_link: link_to(@rotation.name, project_incident_management_oncall_schedules_url(@project).html_safe) }

ee/app/views/notify/user_removed_from_rotation_email.text.haml

+= _("%{user_name} (%{user_username}) was removed from %{rotation} in %{schedule} in %{project}. ") % { user_name: @user.name, user_username: @user.username, rotation: @rotation.name, schedule: @rotation.schedule.name, project: @project.name }
+
+= _("%{rotation} has been recalculated with the remaining participants. Please review the new setup for %{rotation}. It is recommended that you reach out to the current on-call responder to ensure continuity of on-call coverage.") % { rotation: @rotation.name }

ee/spec/services/ee/notification_service_spec.rb

@@ -896,8 +896,9 @@ RSpec.describe EE::NotificationService, :mailer do
   end
 
   context 'IncidentManagement::Oncall' do
+    let_it_be(:user) { create(:user) }
+
     describe '#notify_oncall_users_of_alert' do
-      let_it_be(:user) { create(:user) }
       let_it_be(:alert) { create(:alert_management_alert) }
       let_it_be(:project) { alert.project }
 
@@ -921,5 +922,18 @@ RSpec.describe EE::NotificationService, :mailer do
           .by 1
       end
     end
+
+    describe '#oncall_user_removed' do
+      let_it_be(:schedule) { create(:incident_management_oncall_schedule) }
+      let_it_be(:rotation) { create(:incident_management_oncall_rotation, schedule: schedule) }
+      let_it_be(:participant) { create(:incident_management_oncall_participant, rotation: rotation) }
+
+      it 'sends an email to the owner and participants' do
+        expect(Notify).to receive(:user_removed_from_rotation_email).with(user, rotation, [schedule.project.owner]).once.and_call_original
+        expect(Notify).to receive(:user_removed_from_rotation_email).with(user, rotation, [participant.user]).once.and_call_original
+
+        subject.oncall_user_removed(rotation, user)
+      end
+    end
   end
 end

locale/gitlab.pot

@@ -800,6 +800,12 @@ msgstr ""
 msgid "%{retryButtonStart}Try again%{retryButtonEnd} or %{newFileButtonStart}attach a new file%{newFileButtonEnd}."
 msgstr ""
 
+msgid "%{rotation} has been recalculated with the remaining participants. Please review the new setup for %{rotation_link}. It is recommended that you reach out to the current on-call responder to ensure continuity of on-call coverage."
+msgstr ""
+
+msgid "%{rotation} has been recalculated with the remaining participants. Please review the new setup for %{rotation}. It is recommended that you reach out to the current on-call responder to ensure continuity of on-call coverage."
+msgstr ""
+
 msgid "%{seconds}s"
 msgstr ""
 
@@ -964,6 +970,9 @@ msgstr ""
 msgid "%{userName}'s avatar"
 msgstr ""
 
+msgid "%{user_name} (%{user_username}) was removed from %{rotation} in %{schedule} in %{project}. "
+msgstr ""
+
 msgid "%{user_name} profile page"
 msgstr ""