/* add random background image */

// array of all background images
var bg=['gifs/bg/corniglia.gif', 'gifs/bg/60thSt.gif', 'gifs/bg/barcelona.gif', 'gifs/bg/campoSLucia.gif', 'gifs/bg/edinburgh_Tollbooth.jpg', 'gifs/bg/forestRow.jpg', 'gifs/bg/housesParliament.gif', 'gifs/bg/lindfieldSussex.gif', 'gifs/bg/littleMarcle_court.gif', 'gifs/bg/madrid_Alley.gif', 'gifs/bg/madrid_Mayor.gif', 'gifs/bg/manchesterTownHall.gif', 'gifs/bg/nyc.gif', 'gifs/bg/oxfordRoofs.gif', 'gifs/bg/paris_Bardonnais.gif', 'gifs/bg/paris_Roof.gif', 'gifs/bg/sanMarco.gif', 'gifs/bg/scottishParliament.gif', 'gifs/bg/segovia.gif'];
// try to set cookie to only serve each image once.
// name of cookie
var ckname = 'bgimg';
// cookie field delimiter
var ckdelim = ':';
var ck=new Array();
if(document.cookie != ''){
	var ckl=document.cookie.split('; ');
	for (var i=0;i<ckl.length;i++) {
		var temp=ckl[i].split('=');
		if (temp[0]==ckname) ck=temp[1].split(ckdelim);
	}
}
// check if seen all images
if (ck.length >= bg.length) {
	ck = new Array();
}
// create array of images not looked at
var notSeen=new Array();
for (var i=0;i<bg.length;i++){
	var seen=false;
	for (var j=0;(j<ck.length)&& !seen;j++)
		seen=(i==parseInt(ck[j]));
	if (!seen) notSeen[notSeen.length]=i;
}
// this is the next image
var im=notSeen[parseInt(Math.random()*notSeen.length)];
// update cookie
var expireDate = new Date();
// expires in 3 months
expireDate.setMonth(expireDate.getMonth()+3);
ck[ck.length]=im;
document.cookie = ckname+"="+ck.join(ckdelim)+"; expires="+expireDate.toGMTString();
// write into page
document.writeln('<style type="text/css">');
document.writeln('body {background-image:url('+bg[im]+')}');
document.writeln('</style>');