Registration tickets to be set for registration period

Admin must create at least one registration ticket before creating registration period.

app/models/admin_ability.rb

@@ -123,7 +123,10 @@ class AdminAbility
     can :manage, Commercial, commercialable_type: 'Conference',
                              commercialable_id: conf_ids
     can :manage, Registration, conference_id: conf_ids
-    can :manage, RegistrationPeriod, conference_id: conf_ids
+    can :manage, RegistrationPeriod do |registration_period|
+      conference = registration_period.conference
+      conf_ids.include?(conference.id) && conference.tickets.for_registration.any?
+    end
     can :manage, Booth, conference_id: conf_ids
     can :manage, Question, conference_id: conf_ids
     can :manage, Question do |question|

app/models/conference.rb

@@ -26,7 +26,11 @@ class Conference < ActiveRecord::Base
   has_many :ticket_purchases, dependent: :destroy
   has_many :payments, dependent: :destroy
   has_many :supporters, through: :ticket_purchases, source: :user
-  has_many :tickets, dependent: :destroy
+  has_many :tickets, dependent: :destroy do
+    def for_registration
+      where(registration_ticket: true)
+    end
+  end
   has_many :resources, dependent: :destroy
   has_many :booths, dependent: :destroy
 

app/views/admin/registration_periods/show.html.haml

@@ -25,5 +25,12 @@
         = link_to 'Delete', admin_conference_registration_period_path,
         method: :delete, data: { confirm: 'Are you sure?' }, class: 'btn btn-danger'
     - else
-      - if can? :create, @conference.build_registration_period
-        = link_to 'New Registration Period', new_admin_conference_registration_period_path, class: 'btn btn-primary'
+      - unless @conference.tickets.for_registration.empty?
+        - if can? :create, @conference.build_registration_period
+          = link_to 'New Registration Period', new_admin_conference_registration_period_path, class: 'btn btn-primary'
+      - else
+        .h3.text-left
+          No Registration Tickets!
+          %small
+            = link_to 'Create registration tickets', new_admin_conference_ticket_path
+            before creating the registration period.