/*
PROJECT      Broyce Control Ltd
OWNERSHIP    Optimised Web Design, Philip Kay
ADDRESS      Duken House, Wootton, Bridgnorth, WV15 6EA, UK
TEL          +44 (0) 1746 781 653
MOBILE       +44 (0) 7711 317 681
EMAIL        kay@osltd.co.uk
RIGHTS       The contents and design of these pages are the property of
             the author who grants no rights for copying, distribution
             or reselling without prior written agreement.
COPYRIGHT    Copyright (c) 2009 Optimised Web Design
*/

<!-- This example is from JavaScript: The Definitive Guide, 3rd Edition.   -->
<!-- That book and this example were Written by David Flanagan.            -->
<!-- They are Copyright (c) 1996, 1997, 1998 O'Reilly & Associates.        -->
<!-- This example is provided WITHOUT WARRANTY either expressed or implied.-->
<!-- You may study, use, modify, and distribute it for any purpose,        -->
<!-- as long as this notice is retained.                                   -->

// The constructor function: creates a cookie object for the specified
// document, with a specified name and optional 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 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 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;