1 package controllers

     2 

     3 import play.api.mvc._

     4 import java.security.MessageDigest

     5 

     6 /*

     7  * Application sets a cookie in plain ASCII on the

     8  * clients browser recording the visits of a page.

     9  *

    10  * The cookie data is hashed and stored in the format:

    11  *

    12  * visits_counter/hashed_value 

    13  */

    14 

    15 object Application extends Controller {

    16 

    17   //hash functions: SHA-1, SHA-256, etc

    18   def mk_hash(s: String) : String = {

    19     val hash_fun = MessageDigest.getInstance("SHA-1")

    20     hash_fun.digest(s.getBytes).map{ "%02x".format(_) }.mkString

    21   }

    22 

    23   //extracting from the string .../... the visits

    24   //value and hash

    25   def gt_cookie(c: Cookie) : Int = c.value.split("/") match {

    26     case Array(s, h) if (s.forall(_.isDigit) && mk_hash(s) == h) => s.toInt 

    27     case _ => 0

    28   }

    29 

    30   def mk_cookie(i: Int) : Cookie = {

    31     val hash = mk_hash(i.toString)

    32     Cookie("visits", s"$i/$hash")

    33   }

    34    

    35   def index = Action { request =>

    36     val visits_cookie = request.cookies.get("visits")

    37     val visits = visits_cookie.map(gt_cookie).getOrElse(0)

    38 

    39     val msg = 

    40       if (visits >= 10)

    41         s"You are a valued customer who has visited this site $visits times."               

    42       else s"You have visited this site $visits times."

    43     

    44     Ok(msg).withCookies(mk_cookie(visits + 1))

    45   }     

    46 }

    47 

    48 

    49 

    50