/*  
 * Unobtrusive image rollover with Prototype library, v1.1
 * 
 * Created by Herryanto Siatono
 * Copyright (c) 2007 Pluit Solutions <www.pluitsolutions.com>
 * 
 * Modified by Nicholas Runco
 * - Updated to support Prototype 1.6
 * - Uses class names to identify images
 *
 * This script is freely distributable under the terms of an MIT-style license.
/*------------------------------------------------------------------------------*/

var Rollover = Class.create({
	// provide the container id containing image links to be rolled over.
	initialize: function(id, options) {
		this.id = id;
		this.images = {};
		this.setOptions(options);
		this.observeLinks();
	},

	setOptions: function(options) {
		this.options = {
			rolloverSuffix: 'over',
			selectedSuffix: 'sel',
			suffixSeperator: '_'
		};
		Object.extend(this.options, options || {});
	},

	observeLinks: function() {
		this.links = $$('.' + this.id + ' img','img.'+ this.id);
		for (i=0; i<this.links.length; i++) {
			Event.observe(this.links[i],'mouseover', this.rolloverImage);
			Event.observe(this.links[i],'mouseout', this.rollbackImage);
		}

		images = $$('.' + this.id + ' img','img.'+ this.id);
		for (i=0; i<images.length; i++) {
			imageId = images[i].id;
			if (!imageId) {
				imageId  = this.id + i;
				images[i].id = imageId;
			}
 
			this.images[imageId] = images[i].src;
			images[i].imageRollover = this;

			// preload rollover image
			(new Image()).src = this.parseRolloverImage(images[i]);
 		}
	},

	rolloverImage: function(e) {
		image = Event.element(e);
		if (image.imageRollover) {
			image.imageRollover.images[image.id] = image.src;
			image.src = image.imageRollover.parseRolloverImage(image);  
		}
	},

	rollbackImage: function(e) {
		image = Event.element(e);
		if (image.imageRollover) {
			image.src = image.imageRollover.images[image.id];
		}
	},

	parseRolloverImage: function(image) {
		ext = image.src.substr(image.src.lastIndexOf('.'));
		path = image.src.match(/(.*)\/(.*\.(png|gif|jpg))/)[1]
		filename = image.src.gsub(path, '')
		basename = this.parseBasename(filename);
		basename = this.parseBasename(basename, this.options.suffixSeperator + this.options.selectedSuffix);
		return path + basename + this.options.suffixSeperator + this.options.rolloverSuffix + ext;
	},
	
	parseBasename: function(name, seperator) {
		seperator = seperator || '.';
		found = name.lastIndexOf(seperator);
		if (found > 0) {
			return name.substr(0, found);
		} else {
			return name;
		}
	}
});