redis_controller.rb

class RedisController < ApplicationController
  private
  def render_from_redis(prefix, variation = nil)
    manifest_id = params[:manifest_id]

    if manifest_id.blank?
      current_manifest_key = if variation
                              "#{prefix}:#{variation}:current"
                             else
                              "#{prefix}:current"
                             end
      manifest_id = $redis.get(current_manifest_key)

      if manifest_id.blank?
        manifest_id = Rails.env
      end
    end

    raise "invalid id #{manifest_id}" unless manifest_id =~ /\A(dev|test|[0-9a-f]{32})\Z/i

    html_key = "#{prefix}:#{manifest_id}"

    html = $redis.get(html_key)

    raise ActionController::RoutingError, "#{html_key} not found" if html.blank?

    insert_current_user_meta(html)
    insert_csrf_meta(html)
    transform_html(html)

    render :text => html
  end

  def insert_current_user_meta(html)
    user_serializer = current_user_serializer_class.new(current_user)
    user_json = Rack::Utils.escape_html(user_serializer.to_json)

    html.insert(head_pos(html), <<-HTML)
<meta name="yapp-user" content="#{user_json}">
HTML
  end

  def current_user_serializer_class
    Api::Auth::UserSerializer
  end

  def insert_csrf_meta(html)
    html.insert(head_pos(html), render_to_string(inline: '<%= csrf_meta_tags %>'))
  end

  def head_pos(html)
    head_open = html.index("<head")
    html.index(">", head_open) + 1
  end

  def body_bottom_pos(html)
    html.index("</body>")
  end

  def transform_html(html)
  end

end