/**
  Cookie class.  Reference: "JavaScript: The Definitive Guide" by David Flanagan
  
  @param document The Document object for which the cookie is stored.  Required.
  @param name A string that specifies a name for the cookie. Required.
  @param hours An optional number that specifies the number of hours from now
         after which the cookie should expire.
  @param path An optional string that specifies the cookie path attribute.
  @param domain An optional string that specifies the cookie domain attribute.
  @param secure An optional boolean value that, if true, requests a secure cookie. 
*/
function CBCookie(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;
    }  
    
    this.$path = path ? path : null;
    this.$domain = domain ? domain : null;
    this.$secure = secure ? true : false;
    
}
  
  
/**
  Stores the cookie.
  
*/
CBCookie.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;

}
  

/**
  Loads a cookie.
*/
CBCookie.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 the success code
    return true;
}


/**
  Removes a cookie.
*/
CBCookie.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;
}