boom

app/models/digital_link.rb

@@ -0,0 +1,27 @@
+class DigitalLink < ActiveRecord::Base
+  
+  belongs_to :digital
+  belongs_to :line_item
+
+  before_validation :set_defaults, :on => :create
+  
+  # Can this link stil be used? It is valid if it's less than 24 hours old and was not accessed more than 3 times
+  def authorizable?
+    self.created_at > 1.day.ago and self.access_counter < 3
+  end
+  
+  # This method should be called when a download is initiated.
+  # It returns +true+ or +false+ depending on whether the authorization is granted.
+  def authorize!
+    authorizable? && increment!(:access_counter) ? true : false
+  end
+  
+  private
+  
+  # Populating the secret automatically and zero'ing the access_counter (otherwise it might turn out to be NULL)
+  def set_defaults
+    self.secret = SecureRandom.hex(15)
+    self.access_counter = 0
+  end
+
+end