/**
 * Provides a simple interface for creating, retrieving and clearing cookies.
 */
CookieManager = Class.create();
CookieManager.prototype =
{
	BROWSER_IS_IE:
		(document.all
		 && window.ActiveXObject
		 && navigator.userAgent.toLowerCase().indexOf("msie") > -1
		 && navigator.userAgent.toLowerCase().indexOf("opera") == -1),

	/**
	 * I hate navigator string based browser detection too, but when Opera alone
	 * chokes on cookies containing double quotes...
	 */
	BROWSER_IS_OPERA:
		(navigator.userAgent.toLowerCase().indexOf("opera") != -1),

	initialize: function(options)
	{
		/*
		this.options =
		{
			shelfLife: 365,
			userData: false
		}.extend(options || {});
		*/
		this.options = Object.extend({shelfLife: 365, userData: false}, options || { });

		this.cookieShelfLife = options.shelfLife;
		this.userDataForIE = options.userData;

		// Internet Explorer has a cookie handling bug - if the *combined size*
		// of all cookies stored for a given domain is greater than 4096 bytes,
		// document.cookie will return an empty string. Until this is fixed, we
		// can fall back on IE's proprietary userData behaviour if necessary.
		if (this.BROWSER_IS_IE && this.userDataForIE)
		{
			this.IE_CACHE_NAME = "storage";
			if ($(this.IE_CACHE_NAME) == null)
			{
				var div = document.createElement("DIV");
				div.id = this.IE_CACHE_NAME;
				document.body.appendChild(div);
			}
			this.store = $(this.IE_CACHE_NAME);
			this.store.style.behavior = "url('#default#userData')";
		}
	},

	/**
	 * Returns the value of a cookie with the given name, or <code>null</code>
	 * if no such cookie exists.
	 */
	getCookie: function(aCookieName)
	{
		var result = null;
		if (this.BROWSER_IS_IE && this.userDataForIE)
		{
			this.store.load(this.IE_CACHE_NAME);
			result = this.store.getAttribute(aCookieName);
		}
		else
		{
			for (var i = 0; i < document.cookie.split('; ').length; i++)
			{
				var crumb = document.cookie.split('; ')[i].split('=');
				if (crumb[0] == aCookieName && crumb[1] != null)
				{
					result = crumb[1];
					break;
				}
			}
		}

		if (this.BROWSER_IS_OPERA && result != null)
		{
			result = result.replace(/%22/g, '"');
		}
		return result;
	},

	/**
	 * Sets a cookie with the given name and value.
	 */
	setCookie: function(aCookieName, aCookieValue)
	{
		if (this.BROWSER_IS_IE && this.userDataForIE)
		{
			this.store.setAttribute(aCookieName, aCookieValue);
			this.store.save(this.IE_CACHE_NAME);
		}
		else
		{
			if (this.BROWSER_IS_OPERA)
			{
				aCookieValue = aCookieValue.replace(/"/g, "%22");
			}
			var date = new Date();
			date.setTime(date.getTime() + (this.cookieShelfLife * 24*60*60*1000));
			var expires = '; expires=' + date.toGMTString();
			document.cookie = aCookieName + '=' + aCookieValue + expires + '; path=/';
		}
	},

	/**
	 * Clears the cookie with the given name.
	 */
	clearCookie: function(aCookieName)
	{
		if (this.BROWSER_IS_IE && this.userDataForIE)
		{
			this.store.load(this.IE_CACHE_NAME);
			this.store.removeAttribute(aCookieName);
			this.store.save(this.IE_CACHE_NAME);
		}
		else
		{
			document.cookie =
				aCookieName + '=;expires=Thu, 01-Jan-1970 00:00:01 GMT; path=/';
		}
	}
}