// The constructor function.  Creates a cookie object for the specified
// document,  with a specified name. 
// attributes.  
// Arguments:
//   document: the Document object that the cookie is stored for.  Required.
//   name: a string that specifies a name for the cookie.  Required.
//   hours: an optional number that specifies the number of hours from now
//          that the cookie should expire.
//   path: an optional string that specifies the cookie path attribute.
//   domain: an optional string that specifies the cookie domain attribute.
//   secure: an optional boolean value that, if true, requests a secure cookie.
//
function Cookie(document, name, hours, path, domain, secure)
{
	// All the predefined properties of this object begin with '_'
	// to distinguish them from other properties which are the values to
	// be stored in the cookie.
	this._document = document;
	this._name = name;
	if (hours)
		this._expiration = new Date((new Date()).getTime() + hours*3600000);
	else this._expiration = null;
	if (path) this._path = path; else this._path = null;
	if (domain) this._domain = domain; else this._domain = null;
	if (secure) this._secure = true; else this._secure = false;
}

// This function is the store() method of the Cookie object
Cookie.prototype.store = function()
{
	// First, loop through the properties of the Cookie object and
	// put together the value of the cookie.  Since cookies use the
	// equals sign and semicolons as separators, we'll use colons
	// and ampersands for the individual state variables we store 
	// within a single cookie value.  Note that we escape the value
	// of each state variable, in case it contains punctuation or other
	// illegal characters.
	var cookieval = "";
	for(var prop in this) {
		// ignore properties with names that begin with '_' and also methods
		if ((prop.charAt(0) == '_') || ((typeof this[prop]) == 'function')) 
			continue;
		if (cookieval != "") cookieval += '&';
		cookieval += prop + ':' + escape(this[prop]);
	}

	// Now that we have the value of the cookie, put together the 
	// complete cookie string, which includes the name, and the various
	// attributes specified when the Cookie object was created.
	var cookie = this._name + '=' + cookieval;
	if (this._expiration)
		cookie += '; expires=' + this._expiration.toGMTString();
	if (this._path) cookie += '; path=' + this._path;
	if (this._domain) cookie += '; domain=' + this._domain;
	if (this._secure) cookie += '; secure';

	// Now store the cookie by setting the magic Document.cookie property
	this._document.cookie = cookie;
}

// This function is the load() method of the Cookie object
Cookie.prototype.load = function()
{
	// First, get a list of all cookies that pertain to this document.
	// We do this by reading the magic Document.cookie property
	var allcookies = this._document.cookie;
	if (allcookies == "") return false;

	// Now extract just the named cookie from that list.
	var start = allcookies.indexOf(this._name + '=');
	if (start == -1) return false;   // cookie not defined for this page.
	start += this._name.length + 1;  // skip name and equals sign.
	var end = allcookies.indexOf(';', start);
	if (end == -1) end = allcookies.length;
	var cookieval = allcookies.substring(start, end);

	// Now that we've extracted the value of the named cookie, we've
	// got to break that value down into individual state variable 
	// names and values.  The name/value pairs are separated from each
	// other with ampersands, and the individual names and values are
	// separated from each other with colons.  We use the split method
	// to parse everything.
	var a = cookieval.split('&');  // break it into array of name/value pairs
	for(var i=0; i < a.length; i++)  // break each pair into an array
		a[i] = a[i].split(':');

	// Now that we've parsed the cookie value, set all the names and values
	// of the state variables in this Cookie object.  Note that we unescape()
	// the property value, because we called escape() when we stored it.
	for(var i = 0; i < a.length; i++) {
		this[a[i][0]] = unescape(a[i][1]);
	}

	// We're done, so return the success code
	return true;
}

// This function is the remove() method of the Cookie object.
Cookie.prototype.remove = function()
{
	var cookie;
	cookie = this._name + '=';
	if (this._path) cookie += '; path=' + this._path;
	if (this._domain) cookie += '; domain=' + this._domain;
	cookie += '; expires=Fri, 02-Jan-1970 00:00:00 GMT';

	this._document.cookie = cookie;
}