Integrate auction

Closes #874

app/models/auction.rb

@@ -0,0 +1,63 @@
+class Auction < ActiveRecord::Base
+  enum status: {
+    started: 'started',
+    awaiting_payment: 'awaiting_payment',
+    no_bids: 'no_bids',
+    payment_received: 'payment_received',
+    payment_not_received: 'payment_not_received',
+    domain_registered: 'domain_registered',
+  }
+
+  PENDING_STATUSES = [statuses[:started],
+                      statuses[:awaiting_payment],
+                      statuses[:payment_received]].freeze
+  private_constant :PENDING_STATUSES
+
+  def self.sell(domain_name)
+    create!(domain: domain_name.to_s, status: statuses[:started])
+  end
+
+  def self.pending(domain_name)
+    find_by(domain: domain_name.to_s, status: PENDING_STATUSES)
+  end
+
+  def mark_as_no_bids
+    transaction do
+      DNS::DomainName.new(domain).update_whois
+      no_bids!
+    end
+  end
+
+  def mark_as_payment_received
+    self.status = self.class.statuses[:payment_received]
+    generate_registration_code
+    save!
+  end
+
+  def mark_as_payment_not_received
+    self.status = self.class.statuses[:payment_not_received]
+
+    transaction do
+      save!
+      restart
+    end
+  end
+
+  def domain_registrable?(registration_code = nil)
+    payment_received? && registration_code_matches?(registration_code)
+  end
+
+  private
+
+  def generate_registration_code
+    self.registration_code = SecureRandom.hex
+  end
+
+  def restart
+    self.class.create!(domain: domain, status: self.class.statuses[:started])
+  end
+
+  def registration_code_matches?(code)
+    registration_code == code
+  end
+end