// 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
function _Cookie_store() {
    // 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
function _Cookie_load() {
    // 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.
function _Cookie_remove() {
    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;
}

// Create a dummy Cookie object, so we can use the prototype object to make
// the functions above into methods.

new Cookie();
Cookie.prototype.store = _Cookie_store;
Cookie.prototype.load = _Cookie_load;
Cookie.prototype.remove = _Cookie_remove;