var content;
var romb;
var textH;
var divH;
var drag=false;
var yold=0;
var ystart=-1;
var coef=1;
var polosa;

function getElementPosition(elem){
	var h = elem.offsetHeight;
	var t = 0;
	
    while (elem){
        t+=elem.offsetTop;
        elem=elem.offsetParent;
    }
    return t;
}

function goHome(){
	document.location="index.php";
}

function ShowProps(obj,objName){
	var result="";
	for(var i in obj)
		result+=objName+"."+i+"="+obj[i]+"<br>\n";
	document.write(result);
}

function scrolling(delta){
	var shag=10;
	if(delta>0){
		content.scrollTop=content.scrollTop-shag;
	}
	else if(delta<0){
		content.scrollTop=content.scrollTop+shag;
	}
		var temp=(divH-romb.clientHeight-romb.clientHeight/2)*(content.scrollTop)/(textH-divH);
		romb.style.top=temp;
}

function wheel(event){
	var delta=0;
	if(!event)/*IE*/
		event=window.event;
	if(event.wheelDelta){ /*IE,Opera*/
		delta=event.wheelDelta/120;		
	}
	else if(event.detail){/*Mozilla*/
		delta=-event.detail/3;
	}
	scrolling(delta);
}

function checkRomb(e){
	var y=0;
	if (!e) e = window.event;
	if (e.pageY){
		y=e.pageY;
	}
	else if (e.clientY){
		y=e.clientY+(document.documentElement.scrollTop || document.body.scrollTop) - document.documentElement.clientTop;
	}
	yold=y;
	drag=true;
}

function releaseRomb(){
	drag=false;
}

function moveRomb(e){
	var y=0;
	if (!e) e = window.event;
	if (e.pageY){
		y = e.pageY;
	}
	else if (e.clientY){
		y = e.clientY + (document.documentElement.scrollTop || document.body.scrollTop) - document.documentElement.clientTop;
	}
	
	if(drag){
		pos=y-ystart;
		if(pos>=0 && pos<(divH-romb.clientHeight)){
			romb.style.top=pos;
			//content.scrollTop=textH*pos/(coef*divH);
			//content.scrollTop=(textH-divH)*(pos+romb.clientHeight)/divH;
			content.scrollTop=(textH-divH)*pos/(divH-romb.clientHeight);
		}
	}	
}

function start(){
	var gogogo=0;
	var tags=document.getElementsByTagName("div");

	for(var i=0;i<tags.length;i++){
		if(tags[i].id=="content"){
			content=tags[i];
			gogogo++;
		}
		if(tags[i].id=="polzunok"){
			romb=tags[i];
			gogogo++;
		}
		if(tags[i].id=="polosa"){
			polosa=tags[i];
			gogogo++;
		}	
	}	
	

	if(gogogo<3){
		//alert(document.getElementById("polzunok"));		
	}
	
	if(gogogo==3){
		textH=content.scrollHeight;
		divH=content.clientHeight;
		content.scrollTop=0;
		romb.style.top=0;
		ystart=getElementPosition(romb)+15;
		
		if(textH<=divH){
			romb.style.visibility='hidden';
			polosa.style.visibility='hidden';
		}
		
		romb.onmousedown=checkRomb;
		document.onmouseup=releaseRomb;
		document.onmousemove=moveRomb;
		//ShowProps(romb,"content");

		if (window.addEventListener)
        	/** DOMMouseScroll is for mozilla. */
        	window.addEventListener('DOMMouseScroll', wheel, false);
			/** IE/Opera. */
			window.onmousewheel=document.onmousewheel=wheel;	
	}	
}