function addUnit(id) {
  var val = parseInt(document.getElementById(id).value);
  document.getElementById(id).value = val+1;
  if(id=='night') {
    checkNight();
    checkDate();
  }
}

function lessUnit(id) {
  var val = parseInt(document.getElementById(id).value);
  document.getElementById(id).value = 0;
  if(val > 0) {
    document.getElementById(id).value = val-1;
  }
  if(id=='night') {
    checkNight();
    checkDate();
  }
}

function checkNight() {
  if(document.getElementById('night').value<1) {
    document.getElementById('night').value = 1;
  }
}

function checkNumber(value) {
  var val = 0;
  if(isNaN(value) || value == '') {
    val = 0;
  } else {
    val = parseInt(value);
  }
  
  if(val>99) {
    val = 99;
  }
  if(val<0) {
    val = 0;
  }
  return val;
}

function ageCheck(value) {
  var val = checkNumber(value);
  if(val > 10) {
    val = 10;
  }
  return val;
}

function checkVal(value) {
  var val = 0;
  if(isNaN(value) || value == '') {
    val = 0;
  } else {
    val = parseInt(value);
  }
  if(val<0) {
    val = 0;
  }
  return val;
}

function creditCheck(value) {
  var val = 0;
  var str = '';
  val = checkVal(value);
  if(val<10) {
    str = '000' + val;
  } else if(val<100) {
    str = '00' + val;
  } else if(val<1000) {
    str = '0' + val;
  } else {
    str = val;
  }
  return str;
}

function cvvCheck(value) {
  var val = 0;
  var str = '';
  val = checkVal(value);
  if(val<100) {
    str = '00' + val;
  } else if(val<1000) {
    str = '0' + val;
  } else {
    str = val;
  }
  return str;
}

function checkArrival() {
  var today = new Date();
  var aa = document.getElementById('arrivalYear').value - 0;
  var mm = document.getElementById('arrivalMonth').value - 1;
  var gg = document.getElementById('arrivalDay').value - 0;
  var arrival = new Date();
  arrival.setFullYear(aa);
  arrival.setDate(gg);
  arrival.setMonth(mm);

  if(today.getFullYear()>arrival.getFullYear()) {
    arrival.setFullYear(today.getFullYear());
  }
  /*if(arrival.getTime()<today.getTime()) {
    var indexYear = today.getFullYear() - today.getFullYear();
    document.getElementById('arrivalYear').selectedIndex = indexYear;
    var indexMonth = today.getMonth();
    document.getElementById('arrivalMonth').selectedIndex = indexMonth;
    var indexDay = today.getDate()-1;
    document.getElementById('arrivalDay').selectedIndex = indexDay;
  } else {*/
    var indexYear = arrival.getFullYear() - today.getFullYear();
    document.getElementById('arrivalYear').selectedIndex = indexYear;
    var indexMonth = arrival.getMonth();
    document.getElementById('arrivalMonth').selectedIndex = indexMonth;
    var indexDay = arrival.getDate()-1;
    document.getElementById('arrivalDay').selectedIndex = indexDay;
  //}
}

function checkDeparture() {
  var today = new Date();
  var aaa = document.getElementById('arrivalYear').value - 0;
  var amm = document.getElementById('arrivalMonth').value - 1;
  var agg = document.getElementById('arrivalDay').value - 0;
  var arrival = new Date();
  arrival.setFullYear(aaa);
  arrival.setDate(agg);
  arrival.setMonth(amm);
  var daa = document.getElementById('departureYear').value - 0;
  var dmm = document.getElementById('departureMonth').value - 1;
  var dgg = document.getElementById('departureDay').value - 0;
  var departure = new Date();
  departure.setFullYear(daa);
	departure.setDate(dgg);
	departure.setMonth(dmm);
  
  if(departure.getTime()<(arrival.getTime()+24*60*60*1000)) {
    var milli = arrival.getTime() + document.getElementById('night').value*(24*60*60*1000);
    departure.setTime(milli);
  } else {
    document.getElementById('night').value = (((((departure.getTime()-arrival.getTime())/1000)/60)/60)/24);
  }
  
  var indexYear = departure.getFullYear() - today.getFullYear();
  document.getElementById('departureYear').selectedIndex = indexYear;
  var indexMonth = departure.getMonth();
  document.getElementById('departureMonth').selectedIndex = indexMonth;
  var indexDay = departure.getDate()-1;
  document.getElementById('departureDay').selectedIndex = indexDay;
}

function checkDate() {
  var today = new Date();
  var night = document.getElementById('night').value;
  var aa = document.getElementById('arrivalYear').value - 0;
  var mm = document.getElementById('arrivalMonth').value - 1;
  var gg = document.getElementById('arrivalDay').value - 0;
  var arrival = new Date();
  arrival.setFullYear(aa);
  arrival.setDate(gg);
  arrival.setMonth(mm);
  var millisecondiArrival = arrival.getTime();
  var millisecondiNight = night*24*60*60*1000;
  var millisecondiDeparture = millisecondiArrival + millisecondiNight;
  var departure = new Date();
  departure.setTime(millisecondiDeparture);
  var indexYear = departure.getFullYear() - today.getFullYear();
  document.getElementById('departureYear').selectedIndex = indexYear;
  var indexMonth = departure.getMonth();
  document.getElementById('departureMonth').selectedIndex = indexMonth;
  var indexDay = departure.getDate()-1;
  document.getElementById('departureDay').selectedIndex = indexDay;
}