//
// A utility class for working with cookies
//
// The constructor function: creates a Cookie object for the specified
// document, with a specified name and optional attributes.
// Arguments:
//   document: The Document object for which the cookie is stored. Required.
//   name:     A string that specifies a name for the cookie. Required.
//   hours:    An optional number that specifies the number of hours from now
//             after which 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.$secure = false;
}
//
// Store() method of the Cookie object
//
Cookie.prototype.store = function () {
  // First, loop through the properties of the Cookie object and
  // put together the value of the cookie. Since cookies use the
  // equals sign and semicolons as separators, we'll use colons
  // and ampersands for the individual state variables we store
  // within a single cookie value. Note that we escape the value
  // of each state variable, in case it contains punctuation or other
  // illegal characters.
  var cookieval = "";
  for(var prop in this) {
    // Ignore properties with names that begin with '$' 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;
}
//
// 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
  // must break that value down into individual state variable
  // names and values. The name/value pairs are separated from each
  // other by ampersands, and the individual names and values are
  // separated from each other by colons. We use the split() method
  // to parse everything.
  var a = cookieval.split('&'); // Break it into an 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 success
  return true;
}
//
// 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;
}