/**
 * Select the next news item on the homepage.
 */
function displayNextHomepageNews(sourceID) {
	var lastItem = countNewsItems();
	if (sourceID == lastItem) {
		displayNewsItem(1)
	} else {
		displayNewsItem(sourceID + 1)
	}
}

/**
 * Select the previous item on the homepage.
 */
function displayPreviousHomepageNews(sourceID) {
	var lastItem = countNewsItems();
	if (sourceID == 1) {
		displayNewsItem(lastItem)
	} else {
		displayNewsItem(sourceID - 1)
	}
}

/**
 * Set the visibility of all newsitems
 */
function displayNewsItem(itemID) {
	for (i = 1; i <= countNewsItems(); i++) {
		var style = document.getElementById('article'+i).style
		if (i != itemID) {
			style.display = 'none';
		} else {
			style.display = 'block';
		}
	}
}

/**
 * Somehow resolve the amount of news articles
 */
function countNewsItems() {
	return parseInt(document.getElementById('NewsArticleAmount').value);
}