vCenter = {
	vCenterUrl: 'http://vcentr.com/',
	
	options: {},
	
	panel: function(options)
	{
		if (!this.checkSource())
			return;
			
		this.options = options ? options : {};

		this.writeCookie('vcenter_referrer', 1);
		this.injectPanel.delay(300);
	},
	
	checkSource: function()
	{
		if (this.readCookie('vcenter_referrer'))
			return true;

		if (new RegExp('^'+this.vCenterUrl.replace(/\//g, "\\/")).test(document.referrer))
			return true;

		return false;
	},
	
	/*
	 * Panel injection
	 */
	
	injectPanel: function()
	{
		/*
		 * Inject CSS link
		 */
		var css_link = document.createElement('link');
		css_link.rel = 'stylesheet';
		css_link.type = 'text/css';
		css_link.href = vCenter.vCenterUrl + 'resources/css/vcenter_panel.css';
		document.getElementsByTagName('head')[0].appendChild(css_link);

		/*
		 * Inject panel elements
		 */
		var theme = vCenter.options.theme ? vCenter.options.theme : 'black';
		var vcenter_panel_wrapper = new Element('div', {'class': 'vcenter_panel_wrapper'});
		vcenter_panel_wrapper.innerHTML = '<div class="'+theme+'"><div><p><a href="'+vCenter.vCenterUrl+'">вернуться в сахалинский виртуальный торговый центр</a></p></div></div>';
	
		$(vcenter_panel_wrapper).inject(document.body, 'top');
	},
	
	/*
	 * Cookies
	 */

	writeCookie: function(key, value)
	{
		value = encodeURIComponent(value);
		value += '; path=/';

		var date = new Date();
		var duration = 1; // In days
		date.setTime(date.getTime() + duration * 24 * 60 * 60 * 1000);

		value += '; expires=' + date.toGMTString();
		document.cookie = key + '=' + value;
	},

	readCookie: function(key)
	{
		key = key.replace(/([-.*+?^${}()|[\]\/\\])/g, '\\$1');

		var value = document.cookie.match('(?:^|;)\\s*' + key + '=([^;]*)');
		return (value) ? decodeURIComponent(value[1]) : null;
	}
}