/**
 * @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])});

        if (this.options.onGlide){
            this.options.onGlide();
        }

        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;
  }
});