package controllersimport play.api.mvc._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 and 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: Cookie) : Int = c.value.split("/") match { case Array(s, h) if (s.forall(_.isDigit) && mk_hash(s) == h) => s.toInt case _ => 0 } def mk_cookie(i: Int) : Cookie = { val hash = mk_hash(i.toString) Cookie("visits", s"$i/$hash") } def index = Action { request => val visits_cookie = request.cookies.get("visits") val visits = visits_cookie.map(gt_cookie).getOrElse(0) val msg = if (visits >= 10) s"You are a valued customer who has visited this site $visits times." else s"You have visited this site $visits times." Ok(msg).withCookies(mk_cookie(visits + 1)) } }