http_cache.rb

# frozen_string_literal: true

require 'time'

module Html2rss
  module Web
    ##
    # Collection of methods which set HTTP Caching related headers in the response.
    module HttpCache
      module_function

      ##
      # Sets Expires and Cache-Control headers to cache for `seconds`.
      # @param response [Hash]
      # @param seconds [Integer]
      # @param cache_control [String, nil]
      def expires(response, seconds, cache_control: nil)
        expires_now(response) and return if seconds <= 0

        response['Expires'] = (Time.now + seconds).httpdate

        cache_value = "max-age=#{seconds}"
        cache_value += ",#{cache_control}" if cache_control
        response['Cache-Control'] = cache_value
      end

      ##
      # Sets Expires and Cache-Control headers to invalidate existing cache and
      # prevent caching.
      # @param response [Hash]
      def expires_now(response)
        response['Expires'] = '0'
        response['Cache-Control'] = 'private,max-age=0,no-cache,no-store,must-revalidate'
      end
    end
  end
end