package controllers

import 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))

  }     

}