var SecondsLeft   = 3;
var Running       = true;
var ShowStatus    = true;
var OldStatus     = "";
var NextImagePage = "";

function SetStatusBar(StatusText) {
  if ((OldStatus == "") && (ShowStatus == true)){
    window.status = StatusText;
  }
  else {
    OldStatus = StatusText;
  }
}

function StartSlideShow() {
  Running = true;
  SetStatusBar("Prezentace spuštěna");
  WriteCookie("SlideShowStopped", false);
	var slideButtons=document.getElementsByTagName('a');
	if (slideButtons.length > 0){
		for (var a=0; a<slideButtons.length; a++) {
			if (slideButtons[a].innerHTML == startSlideShow) slideButtons[a].innerHTML = stopSlideShow;
		}
	}
}

function StopSlideShow() {
  Running = false;
  SetStatusBar("Prezentace zastavena");
  WriteCookie("SlideShowStopped", true);
	var slideButtons=document.getElementsByTagName('a');
	if (slideButtons.length > 0){
		for (var a=0; a<slideButtons.length; a++) {
			if (slideButtons[a].innerHTML == stopSlideShow) slideButtons[a].innerHTML = startSlideShow;
		}
	}
}

function StartStop() {
  if (Running == false) {
    StartSlideShow();
  }
  else {
    StopSlideShow();
  }
}

function CountDown() {
  if ((Running == true) && (NextImagePage!="")) {

    if (SecondsLeft > 0) {
      SecondsLeft = SecondsLeft - 1;
    }
    else {
      Running = false;
      document.location = NextImagePage;
    }

    if (SecondsLeft == 0) {
      SetStatusBar("Další obrázek se automaticky načte za " + (SecondsLeft + 1) + " vteřinu");
    }
    else if (SecondsLeft < 4) {
		  SetStatusBar("Další obrázek se automaticky načte za " + (SecondsLeft + 1) + " vteřiny");
		}
		else {
		  SetStatusBar("Další obrázek se automaticky načte za " + (SecondsLeft + 1) + " vteřin");
		}
  }
  setTimeout("CountDown()",1000);
}

function ReadCookie(name, DefaultValue) {
  var cookieValue = escape(DefaultValue);
  var search = name + "=";

  if(document.cookie.length > 0) {

    var offset = document.cookie.indexOf(search);

    if (offset != -1) {

      offset += search.length;
      var end = document.cookie.indexOf(";", offset);

      if (end == -1) end = document.cookie.length;

      cookieValue = unescape(document.cookie.substring(offset, end))
    }

  }

  return cookieValue;
}

function WriteCookie(name, value) {
	document.cookie = name +" =" + escape(value) + ";path=/";
}


function InitSlideShow() {
  if (NextImagePage!=""){
		if (ReadCookie("SlideShowStopped", "false") == "true") {
	    StopSlideShow();
	  }
	  else {
	    StartSlideShow();
	  }
		CountDown();
  }
}

function PageLoaded() {
  InitSlideShow();
	if (NextImageSrc) {
  var imagepreload = new Image;
  imagepreload.src = NextImageSrc;
  }
}
window.onload=PageLoaded;