module Gem::UpdateSuggestion

def eligible_for_update?
  # explicit opt-out
  return false if Gem.configuration[:prevent_update_suggestion]
  return false if ENV["RUBYGEMS_PREVENT_UPDATE_SUGGESTION"]
  # focus only on human usage of final RubyGems releases
  return false unless Gem.ui.tty?
  return false if Gem.rubygems_version.prerelease?
  return false if Gem.disable_system_update_message
  return false if Gem::CIDetector.ci?
  # check makes sense only when we can store timestamp of last try
  # otherwise we will not be able to prevent "annoying" update message
  # on each command call
  return unless Gem.configuration.state_file_writable?
  # load time of last check, ensure the difference is enough to repeat the suggestion
  check_time = Time.now.to_i
  last_update_check = Gem.configuration.last_update_check
  return false if (check_time - last_update_check) < ONE_WEEK
  # compare current and latest version, this is the part where
  # latest rubygems spec is fetched from remote
  (Gem.rubygems_version < Gem.latest_rubygems_version).tap do |eligible|
    # store the time of last successful check into state file
    Gem.configuration.last_update_check = check_time
    return eligible
  end
rescue StandardError # don't block install command on any problem
  false
end

def update_suggestion
  <<-MESSAGE
new release of RubyGems is available: #{Gem.rubygems_version} → #{Gem.latest_rubygems_version}!
n `gem update --system #{Gem.latest_rubygems_version}` to update your installation.
  MESSAGE
end