module Scrivito
class CmsRestApi
module RateLimit
  def self.retry_on_rate_limit(request_timer, &block)
    internal_retry(block, request_timer, 0)
  end

  private_class_method def self.internal_retry(request_proc, request_timer, retry_count)
    response = request_proc.call

    if failed_because_of_rate_limit?(response)
      time_to_sleep = calculate_time_to_sleep(response['Retry-After'].to_f, retry_count)

      if request_timer.cover?(Time.now + time_to_sleep.seconds)
        Warning.warn("Rate limit exceeded. Will retry after #{time_to_sleep} seconds.")
        sleep time_to_sleep
        internal_retry(request_proc, request_timer, retry_count + 1)
      else
        raise Scrivito::RateLimitExceeded.new('rate limit exceeded', 429)
      end
    else
      response
    end
  end

  private_class_method def self.calculate_time_to_sleep(retry_after, retry_count)
    backoff_wait_time = 2 ** retry_count * 0.5
    [backoff_wait_time, retry_after].max
  end

  private_class_method def self.failed_because_of_rate_limit?(response)
    response.code == '429'
  end
end
end
end