/**
* @author Bruno Bornsztein <bruno@missingmethod.com>
* @copyright 2007 Curbly LLC
* @package Glider
* @license MIT
* @url http://www.missingmethod.com/projects/glider/
* @version 0.0.4
* @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.sections = this.wrapper.getElementsBySelector('div.section');
		this.options = Object.extend({ controlsEvent: 'click', duration: 1.0, frequency: 3 }, options || {});

		this.sections.each(function(section, index) {
			section._index = index;
		});

		this.events = {
			click: this.click.bind(this)
		};

		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() {
		this.controls = this.wrapper.getElementsBySelector('.controls a');
		this.controls.invoke('observe', this.options.controlsEvent, this.events.click);
	},

	click: function(event) {
		this.stop();
		var element = Event.findElement(event, 'a');
		if (this.scrolling) this.scrolling.cancel();

		moveTo = this.wrapper.down('#' + element.href.split("#")[1])
		this.moveTo(moveTo, this.scroller, { duration: this.options.duration });
		Event.stop(event);

		this.controls.each(function(control) {
			if (control == element) {
				control.addClassName("active")
			} else {
				control.removeClassName("active")
			}
		});
	},

	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
		});
	},

	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
		});
	},

	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;
	}
});