event :update_follow_rules, :finalize,
      on: :save, when: proc { |c| c.update_all_users } do
  defaults = item_names.map do |item|
    if (set_card = Card.fetch item.to_name.left) && set_card.type_code == :set
      option_card = Card.fetch(item.to_name.right) ||
                    Card[item.to_name.right.to_sym]
      option = if option_card.follow_option?
                 option_card.name
               else
                 '*always'
               end
      [set_card, option]
    elsif (set_card = Card.fetch sug) && set_card.type_code == :set
      [set_card, '*always']
    end
  end.compact
  Auth.as_bot do
    Card.search(type: 'user').each do |user|
      defaults.each do |set_card, option|
        follow_rule = Card.fetch(set_card.follow_rule_name(user.name), new: {})
        next unless follow_rule
        follow_rule.drop_item '*never'
        follow_rule.drop_item '*always'
        follow_rule.add_item option
        follow_rule.save!
      end
    end
  end
  Card.follow_caches_expired
end

format :html do
  view :edit, perms: :update, tags: :unknown_ok do |args|
    frame_and_form :update, args do
      [
        _optional_render(:content_formgroup, args),
        _optional_render(:confirm_update_all, args),
        _optional_render(:button_formgroup,   args)
      ]
    end
  end

  view :confirm_update_all do |args|
    wrap args do
      alert 'info' do
        %(
          <h1>Are you sure you want to change the default follow rules?</h1>
          <p>You may choose to update all existing users.
             This may take a while. </p>
        )
      end
    end
  end

  def default_edit_args args
    args[:hidden] ||= {}
    args[:hidden].reverse_merge!(
      success: '_self',
      card:    { update_all_users: false }
    )
    args[:buttons] = %(
      #{submit_button text: 'Submit and update all users',
                      disable_with: 'Updating', class: 'follow-updater'}
      #{button_tag 'Submit', class: 'follow'}
      #{cancel_button href: path(view: :edit, id: card.id)}
    )
  end
end