require 'net/ldap'

# how to "bind" to your ldap/ad server...
LDAP_HOST = 'server'
LDAP_PORT = 389
LDAP_USERNAME = 'cn=Username;cn=Users;dc=domain;dc=com'
LDAP_PASSWORD = 'your user password'
LDAP_BASE = 'dc=domain;dc=com'

# replace "domain" and "com" above with your AD domain

class User < ActiveRecord::Base
  def member_of?(group)
    @@ldap ||= Net::LDAP.new(
      :host => LDAP_HOST,
      :port => LDAP_PORT,
      :auth => {:method => :simple, :username => LDAP_USERNAME, :password => LDAP_PASSWORD}
    )
    @@ldap.search(
      :base => LDAP_BASE,
      :filter => Net::LDAP::Filter.eq('sAMAccountName', self.username),
      :attributes => %w(memberOf)
    ).first.memberOf.include? "CN=#{group},OU=Groups,DC=domain,DC=com"
  end
end

# this code allows us to test that a user is in a group
@user = User.find(1)
@user.member_of?('staff')