var cratertankImage = null;
var cratertankLink = null;
var cratertankTime = 2000; //milliseconds
var cratertankNumber = 1;
var pageLoadNumber = null;
var clickNumber = null;
var nowString = null;
var randString = null;

function addEvent(theElement, theEvent, theFunction)
{
	if (theElement.attachEvent) theElement.attachEvent("on" + theEvent, theFunction);
	else theElement.addEventListener(theEvent, theFunction, false);
}

function preloadImages(preloadArray)
{
	for (var i = 0; i < preloadArray.length; i++)
	{
		var preImage = document.createElement("img");
		preImage.src = preloadArray[i];
		preImage.style.display = "none";
		document.body.appendChild(preImage);
	}
}

 	function createCookie(name,value,days)
	{
		if (days)
		{
			var date = new Date();
			date.setTime(date.getTime()+(days*24*60*60*1000));
			var expires = "; expires=" + date.toGMTString();
		}
		else var expires = "";
		
		document.cookie = name+"="+value+expires+"; path=/;";
			if (value != "" && readCookie(name) != value)
		{
			return false;
		}
		return true;
	}
	
	function readCookie(name)
	{
		var n = 0;
		var nameEQ = name + "=";
		var ca = document.cookie.split(';');
	
		for(n = 0; n < ca.length;n++)
		{
			var c = ca[n];
			
			while (c.charAt(0)==' ') c = c.substring(1,c.length);
			
			if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
		}
		
		return null;
	}

function changeCratertankImage()
{
	cratertankNumber++;

	if (cratertankNumber > 5) cratertankNumber = 1;

	cratertankImage.src = "http://www.craterfish.org/ads/tank" + cratertankNumber + ".png";

	setTimeout("changeCratertankImage();", cratertankTime);
}

function cratertankWindowLoad()
{
	var now = new Date();
	nowString = now.getFullYear();

	var nowMonth = now.getMonth() + 1;
	if (nowMonth < 10) nowMonth = "0" + nowMonth;

	var nowDay = now.getDate();
	if (nowDay < 10) nowDay = "0" + nowDay;

	var nowHour = now.getHours();
	if (nowHour < 10) nowHour = "0" + nowHour;

	var nowMinute = now.getMinutes();
	if (nowMinute < 10) nowMinute = "0" + nowMinute;

	var nowSecond = now.getSeconds();
	if (nowSecond < 10) nowSecond = "0" + nowSecond;

	nowString = "" + now.getFullYear() + nowMonth + nowDay + nowHour + nowMinute + nowSecond;

	pageLoadNumber = readCookie("cratertank_page_loads");
	if (pageLoadNumber === null) pageLoadNumber = 0;
	else
	{
		pageLoadNumber = parseInt(pageLoadNumber);
		if (isNaN(pageLoadNumber)) pageLoadNumber = 0;
	}
	createCookie("cratertank_page_loads",pageLoadNumber + 1,365);

	clickNumber = readCookie("cratertank_clicks");
	if (clickNumber === null) clickNumber = 0;
	else
	{
		clickNumber = parseInt(clickNumber);
		if (isNaN(clickNumber)) clickNumber = 0;
	}

	cratertankImage = document.getElementById("cratertank");
	cratertankLink = document.getElementById("craterlink");

	randString = Math.random();

	setHref();

	setTimeout("changeCratertankImage();", cratertankTime);
}

function setHref()
{
	cratertankLink.href = "http://www.craterfish.org/ad.php?ad=tank&url=" + escape(document.location) + "&time=" + escape(nowString) + "&pageloads=" + pageLoadNumber + "&clicks=" + clickNumber + "&rand=" + randString;
}

function cratertankClick()
{
	if (nowString)
	{
		clickNumber++;

		createCookie("cratertank_clicks", clickNumber,365);

		setHref();
	}
}

preloadImages(["http://www.craterfish.org/ads/tank2.png",
		"http://www.craterfish.org/ads/tank3.png",
		"http://www.craterfish.org/ads/tank4.png",
		"http://www.craterfish.org/ads/tank5.png"]);

addEvent(window, "load", cratertankWindowLoad);