var timerID = null;
var timerRunning = false;




function stopclock () {
if(timerRunning)
clearTimeout(timerID);
timerRunning = false;
}

function startclock () {
stopclock();
showtime();
}





function showtime() {


// SET DATUM START-KONEC

var today = new Date();
var DatumKonec=new Date();
var DatumStart=new Date();

var mesic=today.getMonth();

DatumStart.setHours(0);
DatumStart.setMinutes(0);
DatumStart.setSeconds(0);

DatumKonec.setHours(23);
DatumKonec.setMinutes(59);
DatumKonec.setSeconds(59);


if (mesic>6-1){
  DatumKonec.setFullYear(today.getFullYear()+1);
}else{
  DatumKonec.setFullYear(today.getFullYear());
}

if (mesic<=6-1){
  DatumStart.setFullYear(today.getFullYear()-1);
}else{
  DatumStart.setFullYear(today.getFullYear());
}



DatumKonec.setDate(30);
DatumKonec.setMonth(5);

DatumStart.setDate(1);
DatumStart.setMonth(8);


konecDen = DatumKonec.getDate();
var Den = DatumKonec.getDay();
if (Den==1) {konecDen=konecDen-3};
if (Den==0) {konecDen=konecDen-2};
if (Den==6) {konecDen=konecDen-1};
DatumKonec.setDate(konecDen);

startDen = DatumStart.getDate();
var Den = DatumStart.getDay();
if (Den==5) {startDen=startDen+3};
if (Den==6) {startDen=startDen+2};
if (Den==0) {startDen=startDen+1};

DatumStart.setDate(startDen);


// END SET DATUM START-KONEC


var skolniRok='0/0';
var Cas='0';



today = new Date();

if ( (today<DatumStart) ){
  skolniRok='Školní rok '+ DatumStart.getFullYear()+'/'+(DatumStart.getFullYear()+1)+ ' začíná za <br>';
  timeLeft = ( DatumStart.getTime() - today.getTime());
}

if ( today>DatumStart ){
  skolniRok='Školní rok '+ DatumStart.getFullYear()+'/'+(DatumStart.getFullYear()+1)+ ' končí za <br>';
  timeLeft = (DatumKonec.getTime() - today.getTime());

}








msPerDay = 24 * 60 * 60 * 1000 ;


e_daysLeft = timeLeft / msPerDay;
daysLeft = Math.floor(e_daysLeft);

e_hrsLeft = (e_daysLeft - daysLeft)*24;
hrsLeft = Math.floor(e_hrsLeft);

minsLeft = Math.floor((e_hrsLeft - hrsLeft)*60);
e_minsLeft = (e_hrsLeft - hrsLeft)*60;

secLeft = Math.floor(e_hrsLeft);
secLeft = Math.floor((e_minsLeft - minsLeft)*60);

Cas=daysLeft+' dní, '+hrsLeft+' hodin a '+minsLeft+' minut.';


if ( (today.getMonth()==DatumKonec.getMonth()) && (today.getDate()==DatumKonec.getDate()) ) {
skolniRok='Dnes končí školní rok <br>';
Cas=(DatumKonec.getFullYear()-1)+'/'+DatumKonec.getFullYear();
}


if ( (today.getMonth()==DatumStart.getMonth()) && (today.getDate()==DatumStart.getDate()) ) {
skolniRok='Dnes začíná školní rok <br>';
Cas=DatumStart.getFullYear()+'/'+(DatumStart.getFullYear()+1);
}


odp1.innerHTML =skolniRok;
odp2.innerHTML =Cas;


timerID = setTimeout("showtime()",1000);
timerRunning = true;
}



startclock();