# Returns a user associated with a facebook account.
def self.find_for_facebook_oauth(access_token, signed_in_resource=nil)
  data = access_token.extra.raw_info
  if user = User.where(:email => data.email).first
    user
  else # Create a user with a stub password.
    user = User.new email: data.email, first_name: data.first_name, last_name: data.last_name, password: Devise.friendly_token[0,20]

    facebook_id = data.id
    token = access_token.credentials.token

    user.facebook_info = { 'id' => facebook_id, 'token' => token }

    # in the future we could save the user and get the friends in a background worker if it's too slow
    fb_user = FbGraph::User.fetch facebook_id, access_token: token
    user.facebook_friends = fb_user.friends.map &:identifier

    user.save!
    user.confirm!
    user
  end
end