var delay = 200; //in milliseconds
    var	drag=false;
    var objDisk=null;
    var x = 0;
    var y = 0;
    var disksOnTower1 = new Array(null,null,null,null,null,null,null,null);
    var disksOnTower2 = new Array(null,null,null,null,null,null,null,null);
    var disksOnTower3 = new Array(null,null,null,null,null,null,null,null);
    var disksOnTowers = new Array(disksOnTower1,disksOnTower2,disksOnTower3);
    var offsetleft = 30;
    var offsettop = 30;
    var offsettower = 20;
    var offsethoriz = 30;
    var basetop = 0;
    var diskheight = 0;
    var midhoriztower = 0;
    var indexTo=1;
    var indexFr=1;
    var movectr=0;
    var gameOver=false;
    var prevIndex=0;
    var zindex = 0;
    var currTower=1;
    var prevTower=1;
    var demo=false;
    var arrFr = new Array(255);
    var arrTo = new Array(255);
    var idx = 0;
    var pos = 0;
    var t=null;
    var stop=false;

    
    function init(){
        if (document.getElementById){
        	var diskno = document.hanoi.diskno;

            diskno.options.selectedIndex = 0;
            drawTowers();
            drawDisks(parseInt(diskno.options[diskno.options.selectedIndex].text));		
        }
    }
    
    function initVars(){
        for (var i=0;i<disksOnTower1.length;i++){
            disksOnTower1[i]=null;
            disksOnTower2[i]=null;
            disksOnTower3[i]=null;
        }
        drag = false;
        indexTo = 1;
        indexFr = 1;
        movectr = 0;
        zindex = 0;
        idx = 0;
        pos = 0;
        t = null;
        gameOver=false;
        stop=false;
        demo=false;
        document.hanoi.btnUndo.disabled=true;
    }
    
    function drawTowers(){
    	var title=document.getElementById("title");
    	var tower1=document.getElementById("tower1");
    	var tower2=document.getElementById("tower2");
    	var tower3=document.getElementById("tower3");
    	var settings=document.getElementById("settings");
        var titlewidth = parseInt(title.style.width);
        var titleheight = parseInt(title.style.height);        
        var towerwidth = parseInt(tower1.style.width);
        var towerheight = parseInt(tower1.style.height);
        var settingswidth = parseInt(settings.style.width);
        midhoriztower = parseInt(document.getElementById("horiztower1").style.width)/2;
        diskheight = parseInt(document.getElementById("disk1").style.height);
                
        title.style.left=offsetleft+(1.5*towerwidth)+offsettower-(titlewidth/2)+"px";
        title.style.top=offsettop+"px";
        tower1.style.left=offsetleft+"px";
        tower1.style.top=offsettop+titleheight+offsethoriz+"px";
        tower2.style.left=offsetleft+towerwidth+offsettower+"px";
        tower2.style.top=offsettop+titleheight+offsethoriz+"px";
        tower3.style.left=offsetleft+(towerwidth+offsettower)*2+"px";
        tower3.style.top=offsettop+titleheight+offsethoriz+"px";
        settings.style.left=offsetleft+(1.5*towerwidth)+offsettower-(settingswidth/2)+"px";
        settings.style.top=parseInt(tower1.style.top)+towerheight+offsethoriz+"px";
    }
    
    function drawDisks(disknum){
    	var tower1=document.getElementById("tower1");
        var disktop = parseInt(tower1.style.top)+parseInt(document.getElementById("horiztower1").style.top);
        var lefttower1 = parseInt(tower1.style.left);
        var disk;
        var f=document.hanoi;
        basetop = disktop;
        for (var i=disksOnTower1.length;i>=1;i--){
        	disk = document.getElementById("disk"+i);
			disk.style.zIndex=++zindex;	
            if (i<=disknum){
                disk.style.left=lefttower1+midhoriztower-parseInt(disk.style.width)/2+"px";
                disk.style.top=disktop-diskheight-1+"px";
                disktop = parseInt(disk.style.top);
                disksOnTowers[0][i-1]=disk;
            }            
            else {
                disk.style.left="-250px";
                disk.style.top="-250px";
                disksOnTowers[0][i-1]=null;
            }
        }       
        f.minmove.value=f.diskno.options[f.diskno.options.selectedIndex].value;
        f.yourmove.value=0;
    }
    
    function newGame(obj){
        if (movectr>0 && !gameOver && !stop){
            if (confirm("??????? ???? ????? ????????, ???????????")){
                initVars();
                drawDisks(parseInt(obj.options[obj.options.selectedIndex].text));
            }
            else document.hanoi.diskno.options.selectedIndex=prevIndex;
        }
        else {
            initVars();
            drawDisks(parseInt(obj.options[obj.options.selectedIndex].text));
        }
    }
    
    function initializeDrag(disk,e){
    	if (!e) e=event;
        if (stop){
            alert("You cannot continue solving the puzzle after clicking the 'Stop' button.\nClick 'Restart' button or select no. of disks to continue playing.");
            return;
        }
        indexFr = indexTo;
        if (disk.id!=disksOnTowers[indexFr-1][0].id || gameOver || demo) return;
        objDisk=disk;
        x=e.clientX;
        y=e.clientY;
        tempx=parseInt(disk.style.left);
        tempy=parseInt(disk.style.top);
        document.onmousemove=dragDisk;
    }
    
    function dragDisk(e){
        if (!e) e=event;
        zindex++;
        drag=true;
        var posX = tempx+e.clientX-x;
        var posY = tempy+e.clientY-y;
        var objTower1 = document.getElementById("tower1");
        var objTower2 = document.getElementById("tower2");
        var objTower3 = document.getElementById("tower3");
        var tower1Left = parseInt(objTower1.style.left);
        var tower2Left = parseInt(objTower2.style.left);
        var tower3Left = parseInt(objTower3.style.left);
        var tower3Width = parseInt(objTower3.style.width);
        
        objDisk.style.zIndex=zindex;
        objDisk.style.left=posX+'px';
        objDisk.style.top=posY+'px';        
        
        if (e.clientX>=document.body.clientWidth-10 || e.clientY>=document.body.clientHeight-5 || e.clientX==5 || e.clientY==5){ //outside available window
            indexTo=indexFr;
            dropDisk(objDisk);
        }
        else if ( //in the vicinity of tower 3
            (tower3Left<=posX) && 
            (tower3Left+tower3Width>=posX) && 
            (parseInt(objTower3.style.top)+parseInt(objTower3.style.height)>posY)
            ){
            indexTo=3;
        }
        else if ((tower2Left<=posX) && (tower2Left+tower3Width>=posX)){ //in the vicinity of tower 2
            indexTo=2;
        }
        else if ((tower1Left<=posX) && (tower1Left+parseInt(objTower1.style.width)>=posX)){ //in the vicinity of tower 1
            indexTo=1;
        }
        else indexTo = indexFr;
        return false;
    }

    function dropDisk(disk){
    	var f=document.hanoi;
        document.onmousemove=new Function("return false");
        if (!drag) return;
        var gameStatus=false;
        var topDisk = disksOnTowers[indexTo-1][0];
        if (indexFr==indexTo){
            getNewTop(indexFr,null);
            pushDisk(disk,indexFr);	//put disk back to original tower
            getNewTop(indexFr,disk);
        }
        else if (topDisk==null) {
            pushDisk(disk,indexTo);
            getNewTop(indexFr,null);
            getNewTop(indexTo,disk);
            movectr++;
            currTower=indexTo;
            prevTower=indexFr;
            f.btnUndo.disabled=false;
        }
        else if (parseInt(disk.style.width)<parseInt(topDisk.style.width)){
            pushDisk(disk,indexTo);
            getNewTop(indexFr,null);
            getNewTop(indexTo,disk);
            movectr++;
            currTower=indexTo;
            prevTower=indexFr;
            if (indexTo==3) gameStatus=checkStatus();
            f.btnUndo.disabled=false;
        }
        else {
            getNewTop(indexFr,null);
            pushDisk(disk,indexFr);	//put disk back to original tower
            getNewTop(indexFr,disk);
        }
      
        drag=false;
        f.yourmove.value=movectr;
        if (gameStatus) {
            f.btnUndo.disabled=true;
            minmove = parseInt(f.minmove.value);
            if (movectr==minmove) msg="\nПоздравления! Вы сделали это за "+minmove+" ходов."
            else if (movectr>minmove) msg="\nДоступны более быстрые решения, чем это."
            else msg="";
            alert("Это конец, а где же пистолет !!!"+msg);
            gameOver=true;
        }
        return;
    }      
    
    function checkStatus(){
        var gameStat = false;
        var disks=0;
        for (var i=0;i<disksOnTower3.length;i++){
            if (disksOnTowers[2][i]!=null) disks++;
        }
        if (disks==parseInt(document.hanoi.diskno.options[document.hanoi.diskno.options.selectedIndex].text)) gameStat=true;
        return gameStat;
    }

    function pushDisk(disk,index){
        var diskWidth = parseInt(disk.style.width);
        var towerLeft = parseInt(document.getElementById("tower"+index).style.left);
        var topDisk = disksOnTowers[index-1][0];
        if (topDisk!=null){
            topDiskWidth = parseInt(topDisk.style.width);
            topDiskTop = parseInt(topDisk.style.top);
            disk.style.left=towerLeft+midhoriztower-diskWidth/2+"px";
            disk.style.top=topDiskTop-diskheight-1+"px";
        }
        else {
            disk.style.left=towerLeft+midhoriztower-diskWidth/2+"px";
            disk.style.top=basetop-diskheight-1+"px";
        }	
    }
   
    function getNewTop(index,disk){
        if (disk==null){		//pop
            for (var i=0;i<disksOnTower1.length-1;i++){
                disksOnTowers[index-1][i]=disksOnTowers[index-1][i+1];
            }
            disksOnTowers[index-1][disksOnTower1.length-1]=null;
        }
        else {		//push
            for (var i=disksOnTower1.length-1;i>=1;i--){
                disksOnTowers[index-1][i]=disksOnTowers[index-1][i-1];
            }
            disksOnTowers[index-1][0]=disk;
        }
    }
    
    function solve(btn){
        if (btn.value=="Solve"){
            if (movectr>0 && !gameOver && !stop)
                if (!confirm("Текущая игра будет прервана, Вы хотите продолжить?")) return;
            btn.value="Stop";
            initVars();
            stop=false;
            demo=true;
            var f=document.hanoi;
            f.btnIns.disabled=true;
            f.btnRes.disabled=true;
            f.btnUndo.disabled=true;
            disknum = parseInt(f.diskno.options[f.diskno.options.selectedIndex].text);
            drawDisks(disknum);
            getMoves(0, 2, 1, disknum); 
            t=window.setTimeout("moveDisk()",delay);
        }
        else {
            if (t) {
                window.clearTimeout(t);
                btn.value="Solve";
                frm.btnIns.disabled=false;
                frm.btnRes.disabled=false;
                t = null;
                stop=true;
                demo=false;
            }
            
        }
    }
    
    function moveDisk(){
        frm = document.hanoi;
        disk=disksOnTowers[arrFr[pos]][0];
        pushDisk(disk,arrTo[pos]+1);
        getNewTop(arrFr[pos]+1,null);
        getNewTop(arrTo[pos]+1,disk);
        movectr++;
        frm.yourmove.value=movectr;
        pos++;
        if (movectr<parseInt(frm.minmove.value)) t=window.setTimeout("moveDisk()",delay);
        else {
            alert("Вы можете это сделать за "+movectr+" ходов?");
            gameOver=true;
            stop=false;
            frm.btnSolve.value="Solve";
            frm.btnIns.disabled=false;
            frm.btnRes.disabled=false;
        }
    }

    function getMoves(from,to,empty,numDisk){
        if (numDisk > 1) {
            getMoves(from, empty, to, numDisk - 1);
            arrFr[idx] = from;
            arrTo[idx++] = to;
            getMoves(empty, to, from, numDisk - 1);
        }
        else {
            arrFr[idx] = from;
            arrTo[idx++] = to;
        }
    }

    
    function unDo(btn){
        disk=disksOnTowers[currTower-1][0];
        pushDisk(disk,prevTower);
        getNewTop(currTower,null);
        getNewTop(prevTower,disk);
        movectr--;
        document.hanoi.yourmove.value=movectr;
        btn.disabled=true;
    }
    
    function displayIns(){
        var msg="Передвиньте все диски с шеста 1 на шест 3.\n";
        msg+="За один ход вы передвигаете только один диск.\n";
        msg+="Вы не можете положить больший диск на меньший.";
        alert(msg);
    }