Add confirmed sponsors

app/models/sponsor.rb

@@ -1,4 +1,6 @@
 class Sponsor < ActiveRecord::Base
+  include ActiveRecord::Transitions
+
   belongs_to :sponsorship_level
   belongs_to :conference
 
@@ -10,4 +12,25 @@ class Sponsor < ActiveRecord::Base
   mount_uploader :picture, PictureUploader, mount_on: :logo_file_name
 
   validates :name, :website_url, :sponsorship_level, presence: true
+
+  scope :confirmed, -> { where(state: 'confirmed') }
+  scope :unconfirmed, -> { where(state: 'uncofirmed') }
+
+  state_machine initial: :uncofirmed do
+    state :uncofirmed
+    state :confirmed
+
+
+    event :confirm do
+      transitions to: :confirmed, from: [:uncofirmed]
+    end
+
+    event :cancel do
+      transitions to: :uncofirmed, from: [:confirmed]
+    end
+  end
+
+  def transition_possible?(transition)
+    self.class.state_machine.events_for(current_state).include?(transition)
+  end
 end