/*
 * LeaveNotice - plug in to notify users of leaving your site
 * Examples and documentation at: http://rewdy.com/tools/leavenotice-jquery-plugin
 * Version: 1.1.1 (09/27/2010)
 * Copyright (c) 2010 Andrew Meyer
 * Licensed under the MIT License: http://en.wikipedia.org/wiki/MIT_License
 * Requires: jQuery v1.4+
*/

(function(jQuery) {
	jQuery.fn.leaveNotice = function(opt){
		
		// define default parameters
		var defaults = {
			siteName: window.location.href,
			exitMessage: "<p><strong>You have requested a website outside of {SITENAME}.</strong></p><p>Thank you for visiting.</p>",
			preLinkMessage: "<div class='setoff'><p>You will now be directed to:<br/>{URL}</p></div>",
			linkString: "", 
			timeOut: 8000,
			overlayId: "ln-blackout",
			messageBoxId: "ln-messageBox",
			messageHolderId: "ln-messageHolder",
			displayUrlLength: 50,
			overlayAlpha: 0.3
		};
		
		var options = jQuery.extend(defaults, opt);
		
		return this.each(function(){
			el = jQuery(this);
			
			//URL the link goes to
			var url=el.attr('href');
			
			//Truncates long URLs to keep 'em pretty
			//Sets length to option value
			var ulen=options.displayUrlLength;
			//If the URL is longer than desired length, add an ellipsis
			if (url.length>=ulen) {
				var suffix = "...";
			} else {
				var suffix = "";	
			}
			//build short URL string
			var shortUrl=url.substr(0,ulen)+suffix;
			
			//Get "title" attribute of the link
			var title=$('img').attr('alt');
			
			//Sets linkText to title if there is one. If not, it defaults to the URL
			if (title!="") {
				var linkText=title;
			} else if (title=="") {
				var linkText=shortUrl;
			}
			
			el.click(function(){
				//Append overlay box
				jQuery('body').append('<div id="' + options.overlayId + '"></div>');
				//Append message holder and message boxes
				jQuery('body').append('<div id="' + options.messageHolderId + '"><div id="' + options.messageBoxId + '"></div></div>');
				//If not turned off in the options, set the opacity on the overlay box to the overlayAlpha option. This is the default while opacity is not supported as a CSS property in all the browsers. In the future, the opacity should be handled from the CSS.
				if (options.overlayAlpha!==false) {
					jQuery('#'+options.overlayId).css('opacity',options.overlayAlpha);
				}
				
				//Put all the HTML together from the options and replace the keywords with their appropriate data.
				preFilteredContent=options.exitMessage + options.preLinkMessage;
				msgContent=preFilteredContent.replace(/\{URL\}/g, '<a href="'+url+'" title="'+url+'"'+options.linkString+'>'+linkText+'</a>');
				msgContent=msgContent.replace(/\{SITENAME\}/g, options.siteName);
				//If timer is enabled, add the close controls to the HTML
				if (options.timeOut>0) {
					msgContent+='<p id="ln-cancelMessage"><a href="#close" id="ln-cancelLink">Cancel</a> or press the ESC key.</p>';
				} else {
					msgContent+='<p id="ln-cancelMessage">Click the link above to continue or <a href="#close" id="ln-cancelLink">Cancel</a></p>';
				}

				//Append the HTML to the message box
				jQuery('#'+options.messageBoxId).append(msgContent);
				
				//If the timer is enabled, set the timer to follow link after desired time.
				if (options.timeOut>0) {
					leaveIn=setTimeout(function(){
						jQuery('#ln-cancelMessage').html('<em>Loading...</em>');
						window.location.href=url;
					},options.timeOut);
				} else {
					leaveIn=false;
				}
				
				//Apply event handler to pressing the close link
				jQuery('#ln-cancelLink').click(function(){
					closeDialog(options, leaveIn);
					return false;
				});
				
				//Set up event handler for the ESC key
				jQuery(document).bind('keyup', function(e){
					if (e.which==27) {
						closeDialog(options, leaveIn);
					}
				});
				
				// Clears the display when leaving the page to prevent it from showing upon returning.
				jQuery(window).unload(function(){
					closeDialog(options, leaveIn);
				});
				
				return false;
			});
		});
	};
	
	// private function to close the dialog. This may be public in future
	// releases, but for now it has to be private.
	function closeDialog(options, timer) {
		if (options.timeOut>0) {
			clearTimeout(timer);
		}
		jQuery('#'+options.overlayId+', #'+options.messageHolderId).fadeOut('fast',function(){
			jQuery('#'+options.overlayId+', #'+options.messageHolderId).remove();
		});
		jQuery(document).unbind('keyup');
	}
	
	// end and return jQuery object
})(jQuery);