/**
 * @author Bruno Bornsztein <bruno@missingmethod.com>
 * @copyright 2007 Curbly LLC
 * @package Glider
 * @license MIT
 * @url http://www.missingmethod.com/projects/glider/
 * @version 0.0.3
 * @dependencies prototype.js 1.5.1+, effects.js
 */
/*  Thanks to Andrew Dupont for refactoring help and code cleanup - http://andrewdupont.net/  */

Glider = Class.create();
Object.extend(Object.extend(Glider.prototype, Abstract.prototype), {
	initialize: function(wrapper, options)
	{
		this.scrolling = false;
		this.wrapper = $(wrapper);
		this.scroller = this.wrapper.down('div.scroller');
		this.scroller_left = $('scroller-left');
		this.scroller_right = $('scroller-right');
		this.sections = this.wrapper.getElementsBySelector('div.section');
		this.options = Object.extend({
			duration: 1.0,
			frequency: 3
		}, options ||
		{});
		
		this.sections.each(function(section, index)
		{
			section._index = index;
		});
		
		this.events = {
			click: this.click.bind(this)
		};
		
		this.scroller_left.hide();
		if (this.sections.length <= 2)
		{
			this.scroller_right.hide();
			return false;			
		}
		
		this.addObservers();
		if (this.options.initialSection) 
			this.moveTo(this.options.initialSection, this.scroller, {
				duration: this.options.duration
			}); // initialSection should be the id of the section you want to show up on load
		if (this.options.autoGlide) 
			this.start();
	},
	
	addObservers: function()
	{
		var controls = this.wrapper.getElementsBySelector('div.controls a');
		controls.invoke('observe', 'click', this.events.click);
	},
	
	click: function(event)
	{
		this.stop();
		var element = Event.findElement(event, 'a');
		if (this.scrolling) 
			this.scrolling.cancel();
		
		this.moveTo(element.href.split("#")[1], this.scroller, {
			duration: this.options.duration
		});
		Event.stop(event);
	},
	
	moveTo: function(element, container, options)
	{
		this.current = $(element);
		
		Position.prepare();
		var containerOffset = Position.cumulativeOffset(container), elementOffset = Position.cumulativeOffset($(element));
		
		this.scrolling = new Effect.SmoothScroll(container, {
			duration: options.duration,
			x: (elementOffset[0] - containerOffset[0]),
			y: (elementOffset[1] - containerOffset[1])
		});
		return false;
	},
	
	next: function()
	{
		if (this.current) 
		{
			var currentIndex = this.current._index;
			var nextIndex = (this.sections.length - 1 == currentIndex) ? 0 : currentIndex + 1;
		}
		else 
		{
			var nextIndex = 1;
		}
		
		this.moveTo(this.sections[nextIndex], this.scroller, {
			duration: this.options.duration
		});
		
		this.scroller_left.show();
		if (this.sections.length <= (currentIndex ? currentIndex : 0) + 3){
			this.scroller_right.hide();
		}
	},
	
	previous: function()
	{
		if (this.current) 
		{
			var currentIndex = this.current._index;
			var prevIndex = (currentIndex == 0) ? this.sections.length - 1 : currentIndex - 1;
		}
		else 
			var prevIndex = this.sections.length - 1;
		
		this.moveTo(this.sections[prevIndex], this.scroller, {
			duration: this.options.duration
		});
		
		this.scroller_right.show();
		if (0 == currentIndex - 1){
			this.scroller_left.hide();
		}
	},
	
	stop: function()
	{
		clearTimeout(this.timer);
	},
	
	start: function()
	{
		this.periodicallyUpdate();
	},
	
	periodicallyUpdate: function()
	{
		if (this.timer != null) 
		{
			clearTimeout(this.timer);
			this.next();
		}
		this.timer = setTimeout(this.periodicallyUpdate.bind(this), this.options.frequency * 1000);
	}
	
});

Effect.SmoothScroll = Class.create();
Object.extend(Object.extend(Effect.SmoothScroll.prototype, Effect.Base.prototype), {
	initialize: function(element)
	{
		this.element = $(element);
		var options = Object.extend({
			x: 0,
			y: 0,
			mode: 'absolute'
		}, arguments[1] ||
		{});
		this.start(options);
	},
	setup: function()
	{
		if (this.options.continuous && !this.element._ext) 
		{
			this.element.cleanWhitespace();
			this.element._ext = true;
			this.element.appendChild(this.element.firstChild);
		}
		
		this.originalLeft = this.element.scrollLeft;
		this.originalTop = this.element.scrollTop;
		
		if (this.options.mode == 'absolute') 
		{
			this.options.x -= this.originalLeft;
			this.options.y -= this.originalTop;
		}
	},
	update: function(position)
	{
		this.element.scrollLeft = this.options.x * position + this.originalLeft;
		this.element.scrollTop = this.options.y * position + this.originalTop;
	}
});