/**
* @author daum
*/
var _ua = window.navigator.userAgent.toLowerCase();

var browser = {
    model: _ua.match(/(sonyericssonx1i|ipod|iphone)/) ? _ua.match(/(sonyericssonx1i|ipod|iphone)/)[0] : "",
	skt : /msie/.test( _ua ) && /nate/.test( _ua ),
	lgt : /msie/.test( _ua ) && /([010|011|016|017|018|019]{3}\d{3,4}\d{4}$)/.test( _ua ),
	opera : /opera/.test( _ua ) || /opera mobi/.test( _ua ),
	ipod : /webkit/.test( _ua ) && /\(ipod/.test( _ua ) ,
	iphone : /webkit/.test( _ua ) && /\(iphone/.test( _ua )
};

// Scroll Button _ FB
function setNav() {
	if(!document.getElementById)	return false;
	if(!document.getElementById('scrollNav'))	return false;

	var nav = document.getElementById('scrollNav');
	var prev = getElementsByClassName(document, "btGoPrev");

	if (hasScroll()) {
		if(browser.skt || browser.lgt) { showScroll(nav); }
		else { hideScroll(nav); }
	} else { hideScroll(nav); }
}

function moveNav(dir, amount) {
	if (amount == undefined) amount = 250;

	switch (dir)
	{
		case 'top':
			window.scrollTo(0,0);
			break;
		case 'up':
			window.scrollTo(0, document.documentElement.scrollTop - amount);
			break;
		case 'down':
			window.scrollTo(0, document.documentElement.scrollTop + amount);
			break;
		defalut:
			break;
	}
}

function hasScroll(){
	var screenHeight = document.documentElement.scrollHeight;
	var clientHeight = document.documentElement.clientHeight;
	return clientHeight < screenHeight ? true : false;
}

function showScroll(nav){
	var offset = 223;

	nav.style.display = "";
	nav.style.top = (document.documentElement.scrollTop + offset) + 'px';
}

function hideScroll(nav){
	nav.style.display = "none";
}

function getElementsByClassName(_element, className){
	var elem = typeof _element == "string" ? document.getElementById(_element) : _element;

	var _all = elem.getElementsByTagName("*");
	var element = [];
	for(var i=0,len=_all.length; i<len; i++) {
		if(_all[i].className == className) element.push(_all[i]);
	}
	return (element.length > 0) ? element : null;
}

if (window.attachEvent)	window.attachEvent("onscroll", setNav);
else	window.addEventListener("scroll", setNav, false);
window.setInterval(setNav, 100);