/**
 * @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.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.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
        });
    },
	
    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;
    }
});