//object definition
function bannerimage(filename,linkhref,buttontext,imgalt) {
	this.filename = filename;		//name of banner filename (without the .jpg)
	this.linkhref = linkhref;		//href that the link should point to
	this.buttontext = buttontext;	//text for the button (also the title attribute of the link)
	this.imgalt = imgalt;}			//alt text for the image - should match the text in the image

//array of bannerimage objects
var banners = [
	new bannerimage(
		'0909-reactive',
		'/centers/reactive/',
		'Get a free T-shirt!',
		'Did you know... The University Store stocks many "green" items and recycled products such as re-usable bottles and glassware, organic cotton t-shirts and recycled notebooks and folders? re-active. reducing, reusing, recycling.'),
//	new bannerimage(
//		'0906-homecoming',
//		'/centers/caro/homecoming/',
//		'Watch the video!',
//		'iPoint - Pump up the Purple. Homecoming 2009, October 4-10.'),
	new bannerimage(
		'0909-adboard',
		'/centers/shoppingservices/board/',
		'Check It Out!',
		'Want to get rid of your old textbooks? Check out the Centers Ad Board to post for roommates, buying and selling books, vehicles, electronics and more!'),
	new bannerimage(
		'0808-latenight',												//filename
		'/centers/centertainment/',										//link
		'Nyctophiles Unite!',											//button text
		'New. UWSP Late Night Programs. The fun starts after 11pm...'),	//img alt text - should include all text that is in the image
	new bannerimage(
		'0901-gamesforrent',
		'/centers/',
		'Play for Free!',
		'PS3 & Wii Systems and Games Now Available for Checkout. Check them out at lower DeBot.'),
	new bannerimage(
		'0812-copies&more',
		'/centers/copies/',
		'Check out the site!',
		'Copies & More. Your on-campus source for copies, photo-printing, banner-printing, bindiing, lamination and more! Located on the DUC 2nd floor.')
//	new bannerimage(
//		'0901-studentemployment',
//		'/centers/employment/',
//		'See what\'s available!',
//		'The University Centers Student Employment Program. What can you offer?')
];

//initialized with a value
var waittime = 5000;					//time to wait on a banner
var moveinterval = 100;					//delay between frames during slide transition
var movepixels = 40;					//pixels to move each frame during transition
var currentbannernum = 0;				//starts with the first banner in the list
var totalwidth = 560;					//width of the banner
var oldside = 0;						//current banner's style.left or style.right is 0px
var newside = totalwidth;				//new banner is entirely out of the frame
var buttonbottomvisible = 3;			//button's style.bottom when visible
var buttonbottomhidden = -33;			//the same when hidden outside the frame
var buttonbottom = buttonbottomvisible;	//button is visible to start
var buttonmovepixels = 12;				//pixels to move animated button per frame
var curstate = 'play';					//banner starts in the 'play' state

//null initialization
var bannerdiv;							//the frame that contains the banners and animation
var curbanner;							//currently displayed banner
var bannerbutton;						//current banner's button
var rightbannernum;						//next banner number to the right
var rightbanner;						//next banner to the right
var leftbannernum;						//...to the the left
var leftbanner;							//...and this too
var playtimer;							//the setTimeout for the delay between switching banners
var scrolltimer;						//the setInterval for banner transition animation
var buttontimer;						//the setInterval to animate the button motion
var animating;							//which side is currently being transitioned to, if any
var pauseplaybutton;					//the pause/play button that changes when clicked

//on page load, sets up button events
function bannerinit() {
	bannerdiv = document.getElementById('banner');
	var leftbutton = document.getElementById('leftbutton');
		leftbutton.onmouseover = function() {leftbutton.src = 'images/bannernavlefthover.gif';}
		leftbutton.onmouseout = function() {leftbutton.src = 'images/bannernavleft.gif';}
		leftbutton.onclick = leftclick;
	pauseplaybutton = document.getElementById('pauseplaybutton');
		pauseplaybutton.onmouseover = function() {pauseplaybutton.src = 'images/bannernavpausehover.gif';}
		pauseplaybutton.onmouseout = function() {pauseplaybutton.src = 'images/bannernavpause.gif';}
		pauseplaybutton.onclick = pauseplayclick;
	var rightbutton = document.getElementById('rightbutton');
		rightbutton.onmouseover = function() {rightbutton.src = 'images/bannernavrighthover.gif';}
		rightbutton.onmouseout = function() {rightbutton.src = 'images/bannernavright.gif';}
		rightbutton.onclick = rightclick;
	curbanner = document.getElementById('currentbanner');
	var startbanner = preparebanner(0);
	bannerdiv.replaceChild(startbanner, curbanner);
	startbanner.setAttribute('id', 'currentbanner');
	curbanner = document.getElementById('currentbanner');
	bannerbutton = curbanner.getElementsByTagName('span')[0];
	bannerbutton.style.bottom = buttonbottom + 'px';
	preparenext();}

//button clicks
function leftclick() {
	if (animating == 'left') { //new banner is coming from the left
		//resetting the position suffices because the scroll() function checks this and will stop animating
		newside = 0;}
	else if (animating == 'right') { //from the right
		curbanner.style.left = '0px';
		bannerdiv.removeChild(rightbanner);
		stopscroll();}
	else { //no banner is sliding
		clearTimeout(playtimer);
		newbanner('left');}}
function rightclick() {
	if (animating == 'right') {
		newside = 0;}
	else if (animating == 'left') {
		curbanner.style.right = '0px';
		bannerdiv.removeChild(leftbanner);
		stopscroll();}
	else {
		clearTimeout(playtimer);
		newbanner('right');}}
function pauseplayclick() {
	if (curstate == 'play') {
		clearTimeout(playtimer);
		curstate = 'pause';
		pauseplaybutton.src = 'images/bannernavplay.gif';
		pauseplaybutton.onmouseover = function() {pauseplaybutton.src = 'images/bannernavplayhover.gif';}
		pauseplaybutton.onmouseout = function() {pauseplaybutton.src = 'images/bannernavplay.gif';}}
	else {
		curstate = 'play'
		if (!animating) newbanner('right'); //start moving banner in from the right
		pauseplaybutton.src = 'images/bannernavpause.gif';
		pauseplaybutton.onmouseover = function() {pauseplaybutton.src = 'images/bannernavpausehover.gif';}
		pauseplaybutton.onmouseout = function() {pauseplaybutton.src = 'images/bannernavpause.gif';}}}

//prepare next banners, left and right
function preparenext() {
	curbanner = document.getElementById('currentbanner');
	curbanner.style.left = '';
	curbanner.style.right = '';
	bannerbutton = curbanner.getElementsByTagName('span')[0];
	if (buttonbottom < buttonbottomvisible) buttontimer = setInterval('movebutton("up");', moveinterval);
	rightbannernum = currentbannernum + 1;
	if (rightbannernum == banners.length) rightbannernum = 0;
	rightbanner = preparebanner(rightbannernum);
	rightbanner.style.left = totalwidth + 'px';
	leftbannernum = currentbannernum - 1;
	if (leftbannernum < 0) leftbannernum = banners.length - 1;
	leftbanner = preparebanner(leftbannernum);
	leftbanner.style.right = totalwidth + 'px';
	//if currently playing, set timeout for banner from the right
	if (curstate != 'pause') playtimer = setTimeout('newbanner("right");', waittime);}

//prepare a banner div
function preparebanner(num) {
	var newdiv = document.createElement('div');
		newdiv.setAttribute('id', 'animbanner');
		newdiv.title = banners[num].buttontext;
	var link = document.createElement('a');
		link.className = 'bannerlink';
		link.href = banners[num].linkhref;
		link.title = banners[num].buttontext;
		newdiv.appendChild(link);
	var image = document.createElement('img');
		image.src = 'banners/' + banners[num].filename + '.jpg';
		image.alt = banners[num].imgalt;
		link.appendChild(image);
	var button = document.createElement('span');
		button.className = 'bannerbutton';
		button.innerHTML = banners[num].buttontext;
		button.style.bottom = buttonbottomhidden + 'px';
		link.appendChild(button);
	return newdiv;}

//transition to next banner (all steps)
function newbanner(side) {
	animating = side;
	clearInterval(buttontimer);
	buttontimer = setInterval('movebutton("down");', moveinterval);}

//move the button
function movebutton(direction) {
	if (direction == 'down') {
		buttonbottom = buttonbottom - buttonmovepixels;
		if (buttonbottom < buttonbottomhidden) buttonbottom = buttonbottomhidden;
		bannerbutton.style.bottom = buttonbottom + 'px';
		if (buttonbottom == buttonbottomhidden) {
			clearInterval(buttontimer);
			slidenext();}}
	else {
		buttonbottom = buttonbottom + buttonmovepixels;
		if (buttonbottom > buttonbottomvisible) buttonbottom = buttonbottomvisible;
		bannerbutton.style.bottom = buttonbottom + 'px';
		if (buttonbottom == buttonbottomvisible) clearInterval(buttontimer);}}

//start slide to next banner
function slidenext() {
	if (animating == 'left') {
		bannerdiv.appendChild(leftbanner);
		scrolltimer = setInterval('scroll();', moveinterval);}
	else {
		bannerdiv.appendChild(rightbanner);
		scrolltimer = setInterval('scroll();', moveinterval);}}

//animated transition
function scroll() {
	newside = newside - movepixels; //position of the new banner
	oldside = newside - totalwidth; //position of the old banner
	if (newside < 0) { //banner would move past the edge this frame, so set position to zero
		oldside = 0 - totalwidth;
		newside = 0;}
	if (animating == 'left') {
		leftbanner.style.right = newside + 'px';
		curbanner.style.right = oldside + 'px';}
	else {
		rightbanner.style.left = newside + 'px';
		curbanner.style.left = oldside + 'px';}
	if (newside == 0) { //new banner has filled the frame
		clearInterval(scrolltimer); //stop scrolling
		oldside = 0; //reset positions
		newside = totalwidth;
		if (animating == 'left') {
			//left banner is the new current banner
			currentbannernum = leftbannernum;
			bannerdiv.replaceChild(leftbanner, curbanner);
			leftbanner.setAttribute('id', 'currentbanner');}
		else {
			currentbannernum = rightbannernum;
			bannerdiv.replaceChild(rightbanner, curbanner);
			rightbanner.setAttribute('id', 'currentbanner');}
		animating = '';
		preparenext();}}

//go back to previous banner
function stopscroll() {
	clearInterval(scrolltimer);
	oldside = 0;
	newside = totalwidth;
	animating = '';
	preparenext();}

//make sure a previous window.onload is not overwritten
if (window.onload) {
	var previnit = window.onload;
	window.onload = function() {
		previnit();
		bannerinit();}}
else window.onload = bannerinit;