clearInterval(newsSliderIntervalHandle);

$(function(){
	var isAnimating = false;
	var newsNum = 4;
	var interval = 3500;
	var $newsCont = $("div.id_news_cont");
	var newsHeight = 26;
	var animationDuration = 1000;
	
	var changeAuto = function() {
		changeNewsAutomatically();
	};
	
	newsSliderIntervalHandle = setInterval(changeAuto, interval);
	
	$("div.id_news_nav").click(function(event){
		event.preventDefault();
		var $target = $(event.target);
		if(!$target.is("a")) {
			return;
		}		
		
		if(isAnimating) {
			return;
		}		
		isAnimating = true;
		
		var currentNewsNum = $target.attr("id").replace("id_news_button_", "");
		currentNewsNum = parseInt(currentNewsNum);
		
		 
		showNews(currentNewsNum, function(){
			isAnimating = false;
		});
 
		clearInterval(newsSliderIntervalHandle);
		newsSliderIntervalHandle = setInterval(changeAuto, interval);
	});
	
	
	function changeNewsAutomatically() {
		if(isAnimating) {
			return;
		}
		isAnimating = true;
		
		var currentNewsNum = $("a.menu_nav_active").attr("id").replace("id_news_button_", "");
		currentNewsNum = parseInt(currentNewsNum);
		
		var nextNewsNum = 1;
		if(currentNewsNum < newsNum) {
			nextNewsNum = currentNewsNum + 1;
		} 
		currentNewsNum = nextNewsNum;
				
		showNews(currentNewsNum, function(){
			isAnimating = false;
		});
	}
	
	function showNews(currentNewsNum,isAnimatingCallback) {				
		var scrollAmount = (currentNewsNum - 1) * ( - newsHeight);
		$('a.menu_nav_active').removeClass('menu_nav_active');
		$('#id_news_button_' + currentNewsNum).addClass('menu_nav_active');
		
		$newsCont.animate({
			"margin-top": scrollAmount
		}, animationDuration, function() {
			if($.isFunction(isAnimatingCallback)) {
				isAnimatingCallback();
			}
		});
	}	
});