// JavaScript Document
var AllBooks = new Array()  ;
var BookOnLeft = 0 ;
var BookCount = 0 ;
var BookCells = 2;

function notUndefined (s)
	{
	if ((typeof s == 'undefined' ) || (s.length==0))
		return '' ;
	else
		return s ;
	}

function PopulateDiv (Div,No)
	{
	var s = "" ;
	var Book = AllBooks[No] ;

	s += '<a href="book.php?xlRow='+Book.xlRow+'">'
	if (notUndefined(Book.imageFile) == '' )
		s += '<img src="data/images/NOIMAGE.jpg"/>' 
	else	
		s += '<img src="data/images/'+Book.imageFile+'" width="128" title="'+Book.title+'" alt="Cover of '+Book.title+'"/>' ;
	s += '<br><h1>' + Book.title + '</h1>' ;
	s += '</a>' ;
	
/*
	s+= '<p class="strap">'+notUndefined(Book.strapline)+'</p>' ;
	s += '<p class="author">'+notUndefined(Book.author)+'</p>' ;
	s += '<div class="specification">' ;
	s += 	'<h2>Specification</h2>' ;
	s += 	'<p>'+notUndefined(Book.spec1)+'</p>' ;
	s += 	'<p>'+notUndefined(Book.spec2)+'</p>' ;
	s += 	'<p>'+notUndefined(Book.spec3)+'</p>' ;
	s += 	'<h2>Rights</h2>' ;
	s += 	'<p>'+notUndefined(Book.rights)+'</p>' ;
	s += '</div>' ;
	s += '<div class="more">' ;
	s += 	'<p>'+notUndefined(Book.descriptionIntro)+'</p>' ;
	s += 	'<p><a href="book.php?xlRow='+Book.xlRow+'">more</a></p>' ;
	s += '</div>' ;
*/
	document.getElementById(Div).innerHTML = s ;
	document.getElementById(Div).style.visibility = "visible" ;
	}

function showArrow (Which,Show)
	{
	if (Show)
		{
		document.getElementById("Arrow"+Which).innerHTML = '<img src="images/arrow'+Which+'.png" title="Scroll '+Which+'" alt="Scroll '+Which+'" onclick="go'+Which+'()"  />' ;
		document.getElementById("Arrow"+Which).style.visibility = "visible" ;
		}
	else
		{
		document.getElementById("Arrow"+Which).innerHTML = '<img src="images/arrow'+Which+'Off.png""  />' ;
		document.getElementById("Arrow"+Which).style.visibility = "hidden" ;
		}
	}

function ZapDiv (Div)
	{
	document.getElementById(Div).innerHTML = "" ;
	document.getElementById(Div).style.visibility = "hidden" ;
	}
	
function PopulateDivs ()
	{
	for (i=0;i<BookCells;i++)
		{
		ZapDiv ("Book"+i) ;
		if (BookCount>i)
			PopulateDiv ("Book"+i,i) ;
		}
	showArrow ("Left",false) ;
	showArrow ("Right",false) ;
	if (BookCount>BookCells)
		showArrow ("Right",true) ;
	}

function goRight ()
	{ // display higher numbered books
	if (AllBooks.length>BookCells)
		{
		BookOnLeft = (BookOnLeft+1) % BookCount ;
		for (i=0;i<BookCells;i++)
			PopulateDiv ('Book'+i,(BookOnLeft+i)%BookCount) ;
		if (BookOnLeft==BookCount-BookCells)
			showArrow("Right",false) ;
		else
			showArrow("Right",true) ;
		showArrow("Left",true) ;

		}	
	}

function goLeft ()
	{ // display lower numbered books
	if (AllBooks.length>BookCells)
		{
		BookOnLeft = (BookOnLeft+BookCount-1) % BookCount ;
		for (i=0;i<BookCells;i++)
			PopulateDiv ('Book'+i,(BookOnLeft+i)%BookCount) ;
		if (BookOnLeft==0)
			showArrow("Left",false) ;
		else
			showArrow("Left",true) ;
		showArrow("Right",true) ;
		}
	}

function getTheBooks (theURL)
	{
	var xml = new JKL.ParseXML( theURL );
	var funcHandleData = function (data) // define call back function
		{
		var i = 0 ;
		for (var x in data.books[0].book)
			AllBooks[i++] = data.books[0].book[x];
		BookCount = i ;
		BookonLeft = 0 ;
		PopulateDivs() ;
		}
	xml.async( funcHandleData );
	xml.setOutputArrayAll() ;
	xml.parse();
	}