class CommonDataSingleton
  include Singleton

  def initialize
    @common_data = nil
    @last_usage = Time.now
  end

  def datasets(visualizations_api_url)
    now = Time.now
    if @common_data.nil? || (now - @last_usage > (cache_ttl * 60))
      @common_data = CommonData.new(visualizations_api_url)
      @last_usage = now
    end
    @common_data.datasets
  end

  def cache_ttl
    ttl = 0
    if Cartodb.config[:common_data].present?
      ttl = Cartodb.config[:common_data]['cache_ttl'] || ttl
    end
    ttl
  end
end