Omniauth setup

auth.rb

Warden::Strategies.add(:login) do
  def authenticate!
    throw :warden
  end
end

WardenOmniAuth.on_callback do |hash|
  HandleAuthentication.new(hash).user
end

Rails.application.config.middleware.instance_eval do
  use OmniAuth::Builder do
    provider :twitter,  ENV['TWITTER_KEY'], ENV['TWITTER_SECRET']
    provider :facebook, ENV['FACEBOOK_ID'], ENV['FACEBOOK_SECRET']
  end
  use Warden::Manager do |manager|
    manager.default_strategies :login, :omni_twitter, :omni_facebook
    manager.failure_app = proc do |env|
      env['rack.session']['warden.pre_failure'] = env['ORIGINAL_FULLPATH']
      [301,{ 'Location' => '/login', 'Content-Type' => 'text/redirect' },['Redirecting you to /login']]
    end
    manager.serialize_into_session do |user|
      user.id
    end
    manager.serialize_from_session do |id|
      MongoAdaptor.new('users',User).fetch(id)
    end
  end
  use WardenOmniAuth do |config|
    config.redirect_after_callback do |env|
      env['rack.session'].delete('warden.pre_failure') || "/"
    end
  end
end