play-2.5 caching with internationalization

Question

I would like to cache a response of a controller while considering the language. With this page here on stackoverflow I was able to make almost everything right but I have one problem when I use the cache and click on a link on the webpage to change the language : it doesn't work directly : the language changes only after I refresh the page and it works perfectly when I try without the cache. The cacheHelper :

package controllers
import play.api.cache.Cached
import play.api.Configuration
import play.api.mvc._
import javax.inject.{ Inject, Singleton }

@Singleton
class CacheHelper @Inject() (val cached: Cached)(implicit configuration: Configuration) {

  def apply(label: String, duration: Int)(action: EssentialAction) = {
    cached({ r: RequestHeader => label + "." + getLanguage(r) }, duration) { action }
  }

  def getLanguage(request: RequestHeader): String = {
    request.cookies.get("PLAY_LANG").map(_.value).getOrElse("fr")
  }
}

the controller :

package controllers
 import javax.inject._
import play.api.i18n._
import scala.concurrent.ExecutionContext
import play.api.mvc.{Action, Controller, EssentialAction, RequestHeader}
@Singleton
class ActuController @Inject() (val cacheHelper: CacheHelper, val messagesApi: MessagesApi)(implicit ec: ExecutionContext) extends Controller with I18nSupport {

  def index = cacheHelper("homePage", 60) {
    Action { implicit req =>
      cacheHelper.getLanguage(req) match {
        case "fr" => Ok("Bonjour le monde")
        case "ru" => Ok("привет")
        case _ => Ok("hello")
      }
    }
  }

}

I have tried to set directly a "PLAY_LANG" cookie instead of using #withLang directly but it doesn't work either. Any ideas ? Thanks.

the "language changer" :

package controllers


import play.api.mvc._
import play.api.i18n.{ MessagesApi, Messages, Lang }
import javax.inject.{ Inject, Singleton }

import play.api.cache.Cached
@Singleton
class Application @Inject() (val messagesApi: MessagesApi) extends Controller {

  def selectLang(lang: String) = Action { implicit request =>
    request.headers.get(REFERER).map { referer =>
      Redirect(referer).withLang(Lang(lang))

    }.getOrElse {
      Redirect(routes.Application.index).withLang(Lang(lang))

    }
  }
}