18F/identity-idp

# frozen_string_literal: true

class BrowserCache
  @cache = LruRedux::Cache.new(1_000)
  # rubocop:disable Style/MutableConstant
  DEFAULT_BROWSER = Browser.new(nil)
  # rubocop:enable Style/MutableConstant
  USER_AGENT_SIZE = Browser.user_agent_size_limit - 1

  # Detects browser attributes from User-Agent, truncated to 2047 bytes due
  # to: https://github.com/fnando/browser/blob/fa4f685482c315b8/lib/browser/browser.rb#L64-L65
  # @param [String] user_agent
  # @return [Browser]
  def self.parse(user_agent)
    return DEFAULT_BROWSER if user_agent.nil?

    @cache.getset(user_agent) do
      Browser.new(user_agent.mb_chars.limit(USER_AGENT_SIZE).to_s)
    end
  end

  # Should probably only be used in tests
  def self.clear
    @cache.clear
  end
end