handle distributed user session

helper.rb

def auth_user user=nil
  #token = JWT.decode(params[:token], hmac_secret, true, { :algorithm => 'HS256' })
  token = request.env["HTTP_TOKEN"]

  halt 401, "token + user are nil" if (token.blank? && user.blank?)

  @user ||= CACHE.get(token)

  unless @user.blank?
    halt 400, "existent user for a blank token" if token.blank?
    @user = JSON.parse(@user,:symbolize_names => true)[:user]
    return @user
  end

  if @user.blank?
    if user.blank?
      halt 401
    else
      token = JWT.encode({uid: user.id.to_s, expires_in: 'never'}, HMAC_SECRET, 'HS256')
      _user = {
        id: user.id.to_s,
        username: user.username,
        name: user.name,
      }
      CACHE.set(token,{user: _user}.to_json)
      @user = _user
    end
  end

  @user
end