var news;
var first_headline;
var news_height;
margin_percentage = 0;
scroll_timeout = 10;
scroll_interval = 3000;

if(window.addEventListener) window.addEventListener('load', prepNews, false);
else if(window.attachEvent) window.attachEvent('onload', prepNews);

function prepNews() {
	news = document.getElementById('newsHeadlines');
	news.style.overflow = 'hidden';
	first_headline = news.getElementsByTagName('li')[0];
	first_headline.style.marginTop = 0;
	if(navigator.userAgent.toLowerCase().indexOf('msie 6') == -1) {
		news_fade = document.createElement('img');
		news_fade.setAttribute('src', 'img/news_fade.png');
		news_fade.style.marginTop = '-30px';
		news.parentNode.insertBefore(news_fade, news.nextSibling);
	}
	target_news_height = Math.round(news.offsetHeight*2/3);
	shrink_news();
}
function shrink_news() {
	news_height = news.offsetHeight;
	if(news_height > target_news_height) {
		news_height -= 2;
		news.style.height = news_height + 'px';
		setTimeout(shrink_news, 10);
	}
	else setTimeout(scrollNews, scroll_interval);	
}

function scrollNews() {
	if((margin_percentage) < 100) {
		margin_percentage += 0.5;
		first_headline.style.marginTop = '-' + Math.round(first_headline.offsetHeight * getOffset(margin_percentage)) + 'px';
		setTimeout(scrollNews, scroll_timeout);
	}
	else {
		scrolled_news = news.removeChild(first_headline);
		margin_percentage = 0;
		scrolled_news.style.marginTop = 0;
		news.appendChild(scrolled_news);
		first_headline = news.getElementsByTagName('li')[0];
		setTimeout(scrollNews, scroll_interval);
	}
}

function getOffset(percentage) {
	return(percentage / 100);
	//return((Math.sin((percentage - 50) / 100 * Math.PI) + 1) / 2);
	//return(Math.sin(percentage / 100 * Math.PI / 2));
}