var checked_de = 0;
var checked_at = 0;
var felder = 6;

function check_checked(checkbox, was){
  if(was == 'de'){
    if(checkbox.checked == true && checked_de <= felder){
      checked_de++;
    }
    if(checkbox.checked == false && checked_de >= 1){
      checked_de--;
    }
    if(checked_de == (felder+1)){
      alert('Bitte wählen sie maximal '+felder+' Zahlen aus.');
      checkbox.checked = false;
      checked_de--;
    }
    document.getElementById('verbleibend_de').innerHTML = (felder-checked_de);
  }
  else if(was == 'at'){
    if(checkbox.checked == true && checked_at <= felder){
      checked_at++;
    }
    if(checkbox.checked == false && checked_at >= 1){
      checked_at--;
    }
    if(checked_at == (felder+1)){
      alert('Bitte wählen sie maximal '+felder+' Zahlen aus.');
      checkbox.checked = false;
      checked_at--;
    }
    document.getElementById('verbleibend_at').innerHTML = (felder-checked_at);
  }
  
}

function zufallszahlen(was){
  if(was == 'de'){
    for (var i = 1; i <= 49; i++){
      document.getElementById('checkbox_de_'+i).checked = false;
    }
    for (var i = 1; i <= felder; i++){
      zufall = Math.random();
      zufall = zufall*49;
      zufall = Math.ceil(zufall);
      if(document.getElementById('checkbox_de_'+zufall).checked == true){
        i--;
      }
      document.getElementById('checkbox_de_'+zufall).checked = true;
    }
    checked_de = felder;
    document.getElementById('verbleibend_de').innerHTML = (felder-checked_de);
  }
  else if(was == 'at'){
    for (var i = 1; i <= 45; i++){
      document.getElementById('checkbox_at_'+i).checked = false;
    }
    for (var i = 1; i <= felder; i++){
      zufall = Math.random();
      zufall = zufall*45;
      zufall = Math.ceil(zufall);
      if(document.getElementById('checkbox_at_'+zufall).checked == true){
        i--;
      }
      document.getElementById('checkbox_at_'+zufall).checked = true;
    }
    checked_at = felder;
    document.getElementById('verbleibend_at').innerHTML = (felder-checked_at);
  }
}

function deaktivieren(was){
  if(was == 'de'){
    for (var i = 1; i <= 49; i++){
      document.getElementById('checkbox_de_'+i).checked = false;
    }
    checked_de = 0;
    document.getElementById('verbleibend_de').innerHTML = (felder-checked_de);
  }
  else if(was == 'at'){
    for (var i = 1; i <= 45; i++){
      document.getElementById('checkbox_at_'+i).checked = false;
    }
    checked_at = 0;
    document.getElementById('verbleibend_at').innerHTML = (felder-checked_at);
  }
}

function change_felder(anz, was){
  felder = anz;
  document.getElementById('felder_'+was).value = anz;
  document.getElementById('kosten_schein_'+was).innerHTML = document.getElementById('kosten_schein_'+anz).value;
  if(was == 'de'){
    for (var i = 1; i <= 49; i++){
      document.getElementById('checkbox_de_'+i).checked = false;
    }
    checked_de = 0;
    document.getElementById('verbleibend_de').innerHTML = (felder-checked_de);
  }
  else if(was == 'at'){
    for (var i = 1; i <= 45; i++){
      document.getElementById('checkbox_at_'+i).checked = false;
    }
    checked_at = 0;
    document.getElementById('verbleibend_at').innerHTML = (felder-checked_at);
  }
}