package controllersimport play.api._import play.api.mvc._import play.api.data._import play.api.data.Forms._import java.security.MessageDigest/* * Application sets a cookie in plain ASCII on the * clients browser recording the visits of a page. * * The cookie data is hashed ans stored in the format: * * visits_counter/hashed_value */object Application extends Controller { //hash functions: SHA-1, SHA-256, etc def mk_hash(s: String) : String = { val hash_fun = MessageDigest.getInstance("SHA-1") hash_fun.digest(s.getBytes).map{ "%02x".format(_) }.mkString } //extracting from the string .../... the visits //value and hash def gt_cookie(c: Option[Cookie]) : Int = c.map(_.value.split("/")) match { case Some(Array(s, h)) if (s.forall(_.isDigit) && mk_hash(s) == h) => s.toInt case _ => 0 } def mk_cookie(i: Int) : Cookie = { val s = i.toString Cookie("visits", s + "/" + mk_hash(s)) } def index = Action { request => val visits_cookie = request.cookies.get("visits") val visits = gt_cookie(visits_cookie) val msg1 = "You are a valued customer who has visited this site %d times." val msg2 = "You have visited this site %d times." val msg = if (visits >= 10) msg1.format(visits) else msg2.format(visits) Ok(msg).as(HTML).withCookies(mk_cookie(visits + 1)) } }