function $_(id) { return document.getElementById(id); }
// monthly amounts
var total_amount_eur = 0;
var platforms_amount_eur = 0;
var categories_amount_eur = 0;
var total_amount_us = 0;
var platforms_amount_us = 0;
var categories_amount_us = 0;
var categ_inclusive = 1;

var categ_eur = 15;
var categ_us = 21;
var plat_eur = 37.50;
var plat_us = 55.00;

var eur = ",- €";
var us = "$ ";

function displaySelectedPlatforms()
{
 if($_("plat_de").checked == true) $_("selected_de").style.visibility = "visible";
 else                       $_("selected_de").style.visibility = "hidden";
 if($_("plat_en").checked == true) $_("selected_en").style.visibility = "visible";
 else                       $_("selected_en").style.visibility = "hidden";
 if($_("plat_es").checked == true) $_("selected_es").style.visibility = "visible";
 else                       $_("selected_es").style.visibility = "hidden";
}

function innerHTMLbyClass(_class, html)
{
 elems = document.getElementsByTagName("*");
 for (var i=0; i<elems.length; i++)
 {
  if (elems[i].className && elems[i].className == _class) { elems[i].innerHTML = html; }
 }
}

function calculateAmount()
{
 inputs = document.getElementsByTagName("input");
 categs_checked = 0;
 plats_checked = 0;
 for (var i=0; i<inputs.length; i++)
 {
  if (inputs[i].name == "categories[]" && inputs[i].checked == true) {
   categs_checked++;
  }
  if (inputs[i].value == "true" && inputs[i].checked == true) { // value=true only for platform_checkboxes !!
   plats_checked++;
  }
 }
 var yearly_eur, yearly_us = 0;
 categories_amount_eur = categs_checked * categ_eur - categ_inclusive * categ_eur;
 categories_amount_us = categs_checked * categ_us - categ_inclusive * categ_us;
 if (categories_amount_eur < 0) { categories_amount_eur = 0; categories_amount_us = 0; }
 platforms_amount_eur = plats_checked * plat_eur;
 platforms_amount_us = plats_checked * plat_us;
 total_amount_eur = platforms_amount_eur + categories_amount_eur;
 total_amount_us  = platforms_amount_us + categories_amount_us;

 displaySelectedPlatforms();
 $_("categs_count").innerHTML = categs_checked;
 if ($_("eu_curr").checked == true)
 {
  yearly_eur = (platforms_amount_eur * 12) / plats_checked;



  innerHTMLbyClass("plats_amount", yearly_eur+eur);
  yearly_eur = categories_amount_eur * 12;

  $_("categs_yearly"). innerHTML = yearly_eur+eur;
  yearly_eur = total_amount_eur * 12;

  $_("amount_yearly").innerHTML = yearly_eur+eur;
 }
 else
 {
  yearly_us = (platforms_amount_us * 12) / plats_checked;



  innerHTMLbyClass("plats_amount", us+yearly_us);
  yearly_us = categories_amount_us * 12;

  $_("categs_yearly"). innerHTML = us+yearly_us;
  yearly_us = total_amount_us * 12;

  $_("amount_yearly").innerHTML = us+yearly_us;
 }
}

function elementsAddOnclick(elems, type)
{
 for (var i=0; i < elems.length; i++)
 {
  if (elems[i].type == type) {
   elems[i].onclick = function() { calculateAmount(); }
  }
 }
}
 window.onload = function() {
  elementsAddOnclick(document.getElementsByTagName("input"), 'checkbox');
  elementsAddOnclick(document.getElementsByTagName("input"), 'radio');
  document.getElementById("resetbutton").onclick = function() { setTimeout("calculateAmount()",100); }

  calculateAmount();
 }