Registration of user and account: the GrantEvent class for managing the granting of roles

grant_event.rb

# see https://gist.github.com/RichardJordan/9059633 for explanation
# -----------------------------------------------------------------

###################################################
# create_table "grant_events", force: true do |t| #
#   t.integer  "role_id", null: false             #
#   t.integer  "user_id"                          #
#   t.string   "name", null: false                #
#   t.datetime "created_at"                       #
#   t.datetime "updated_at"                       #
# end                                             #
###################################################

class GrantEvent < ActiveRecord::Base
  belongs_to :role
  belongs_to :user

  attr_writer :user_fetcher

  def allow
    create_event :grant
  end

  def deny
    create_event :revoke
  end

  def granter
    user_id ? user_fetcher.call(user_id) : CustomerSupportUser.new
  end

  def granter=(granter_user)
    self.user_id = granter_user.id
  end

  private

  def create_event(state)
    self.name = state.to_s
    role.add_event(self)
  end

  def user_fetcher
    @user_fetcher ||= User.public_method(:find_by_id)
  end

end