API for apps to register for push notifications

app/services/send_push_notification_service.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+class SendPushNotificationService < BaseService
+  def call(notification)
+  	return if ENV['FCM_API_KEY'].blank?
+
+  	devices = Device.where(account: notification.account).pluck(:registration_id)
+  	fcm     = FCM.new(ENV['FCM_API_KEY'])
+
+  	response = fcm.send(devices, data: { notification_id: notification.id }, collapse_key: :notifications, priority: :high)
+  	handle_response(response)
+  end
+
+  private
+
+  def handle_response(response)
+    update_canonical_ids(response[:canonical_ids]) if response[:canonical_ids]
+    remove_bad_ids(response[:not_registered_ids])  if response[:not_registered_ids]
+  end
+
+  def update_canonical_ids(ids)
+  	ids.each { |pair| Device.find_by(registration_id: pair[:old]).update(registration_id: pair[:new]) }
+  end
+
+  def remove_bad_ids(bad_ids)
+  	Device.where(registration_id: bad_ids).delete_all
+  end
+end