class GdsApi::JsonClient

def response_cache_time(response)
  if response.headers[:cache_control]
    # The Cache-control header is composed of a comma-separated string
    # so split this apart before we look for particular values
    cache_parts = response.headers[:cache_control].split(',').map(&:strip)
    # If no-cache is present, this takes precedent over any other value
    # in this header
    return Time.now.utc if cache_parts.include?("no-cache")
    # Otherwise, look for a 'max-age=123' value, which is the number of
    # seconds for which to cache the response.
    max_age = cache_parts.map {|x| x.match(/max-age=(\d+)/) }.compact.first
    if max_age
      return Time.now.utc + max_age[1].to_i
    end
  end
  if response.headers[:expires]
    Time.httpdate response.headers[:expires]
  end
end