//Builds a carousel model
//License: This file is entirely BSD licensed.
//Author: Brian R Miedlar (c) 2004-2008 miedlar.com
//Dependencies: prototype.js, behaviour.js

var CarouselItem = Class.create();
CarouselItem.prototype = {
  initialize: function() {
    //this.key = null;		
    this.value = null;
    this.element = null;
  }
};
var Carousel = Class.create();
Carousel.prototype = {
  initialize: function(carouselElement, itemWidth, itemHeight, observer, options) {
    //this.key = key;
    this.observer = observer;
    this.items = [];
    this.activeItem = null;
    this.navScrollIndex = 0;
    this.duration = 1.0;
    if(options.duration) this.duration = options.duration;
    this.options = options;
    this.direction = 'vertical';
    if(options.direction) this.direction = options.direction;
    this.itemHeight = itemHeight;
    this.itemWidth = itemWidth;
    this.moveOpacity = .6;
    this.setSize = 4;
    if(options.setSize) this.setSize = options.setSize;
    this.carouselElement = $(carouselElement);
    if(!this.carouselElement) { alert('Warning: Invalid carousel element: ' + carouselElement); return; }
    this.itemsElement = this.carouselElement.down('.items');
    if(!this.itemsElement) { alert('Warning: Class \'items\' does not exist as a child element in carousel: ' + carouselElement); return; }
    this.backElement = this.carouselElement.down('.navButton.previous');
    this.forwardElement = this.carouselElement.down('.navButton.next');
    Event.observe(this.backElement, 'click', function(ev){
      ev.stop();
      this.scrollBack();
    }.bind(this));
    Event.observe(this.forwardElement, 'click', function(ev){
      ev.stop();
      this.scrollForward();
    }.bind(this));
  },
  load: function() {
    var eList = this.itemsElement;
    this.items.clear();
    eList.select('.item').each(function(item) {
      item.carouselKey = null;
      var sKey = '';
      try {
        sKey = item.down('.key').innerHTML;
      } catch(e) {
        alert('Warning: Carousel Items require a child with classname [key]');
        return;            
      }

      var oCarouselItem = new CarouselItem();
      if(this.options.itemParser) oCarouselItem.value = this.options.itemParser(item);
      oCarouselItem.index = this.items.length;
      oCarouselItem.key = sKey;
      oCarouselItem.element = item;
      this.items.push(oCarouselItem);

      if(this.options.setItemEvents) this.options.setItemEvents(this, item, oCarouselItem, this.observer);            
    }.bind(this));

    //Post processing        
    this.afterLoad();
  },
  afterLoad: function() {
    if(this.items.length == 0) {
      return;
    }
    this.scrollToIndex(0);        
    if(this.observer.fireActiveCarouselLoaded) this.observer.fireActiveCarouselLoaded(this);
  },
  scrollForward: function() {    
    //setsize-1 at a time scrolling 
    if(this.navScrollIndex > this.items.length - (this.setSize+1)) return;
    var iIndex = this.navScrollIndex + (this.setSize-1);
    this.scrollToIndex(iIndex);
  },
  scrollBack: function() {
    var iIndex = this.navScrollIndex - (this.setSize-1);
    if(iIndex < 0) iIndex  = 0;
    this.scrollToIndex(iIndex);
  },
  getLeft: function(index) {
    return index * (-this.itemWidth);
  },
  getTop: function(index) {
    return index * (-this.itemHeight);
  },
  activate: function(carouselItem) {
    if(this.activeItem) this.observer.fireDeactiveCarouselItem(this, this.activeItem.element, this.activeItem);
    if(carouselItem == null) return; 
    this.activeItem = carouselItem;
    if(this.observer.fireActiveCarouselItem) this.observer.fireActiveCarouselItem(this, carouselItem.element, carouselItem);
  },
  next: function() {
    if(this.activeItem == null) { this.activate(this.items[0]); return; }
    var iIndex = this.activeItem.index + 1;
    if(iIndex >= this.items.length) iIndex = 0;
    this.activate(this.items[iIndex]);
  },
  previous: function() {
    if(this.activeItem == null) { this.activate(this.items[0]); return; }
    var iIndex = this.activeItem.index - 1;
    if(iIndex < 0) iIndex = 0;
    this.activate(this.items[iIndex]);
  },
  scrollToIndex: function(index) {        
    if(this.direction == 'vertical') {
      var iPreviousTop = this.getTop(this.navScrollIndex);
      var iTop = this.getTop(index);
      var iCurrentTop = parseInt(Element.getStyle(this.itemsElement, 'top')) || 0;
      var offset = iPreviousTop-iCurrentTop;
      var move = iTop - iPreviousTop;
      if(move > 0) {
        move = move + offset;
      } else {
        move = move - offset;
      }
      Element.setOpacity(this.itemsElement, this.moveOpacity);
      var ef = new Effect.Move(this.itemsElement, {
        'duration': this.duration,
        'y': move, 
        'afterFinish': function() { 
          Element.setStyle(this.itemsElement, {'top':iTop + 'px'});
          Element.setOpacity(this.itemsElement, 1.0);
        }.bind(this)
      });
      ef = null;
    } else {
      var iPreviousLeft = this.getLeft(this.navScrollIndex);
      var iLeft = this.getLeft(index);
      var iCurrentLeft = parseInt(Element.getStyle(this.itemsElement, 'left')) || 0;
      var offset = iPreviousLeft - iCurrentLeft;
      var move = iLeft - iCurrentLeft;
      if(move > 0) {
        move = move + offset;
      } else {
        move = move - offset;
      }
      Element.setOpacity(this.itemsElement, this.moveOpacity);
      var ef = new Effect.Move(this.itemsElement, {
        'duration': this.duration,
        'x': move, 
        'afterFinish': function() { 
          Element.setStyle(this.itemsElement, {'left':iLeft + 'px'});
          Element.setOpacity(this.itemsElement, 1.0);
        }.bind(this)
      });
      ef = null;
    }
    this.navScrollIndex = index;
    Element.display(this.forwardElement, this.navScrollIndex <= this.items.length - (this.setSize+1));
    Element.display(this.backElement, (parseInt(this.navScrollIndex) || 0) != 0);
    if(this.observer.fireCarouselAtIndex) this.observer.fireCarouselAtIndex(this, index);
  },
  moveToIndex: function(index) {
    if(this.direction == 'vertical') {
      var iTop = this.getTop(index);
      Element.setStyle(this.itemsElement, {'top':iTop + 'px'});
      Element.setOpacity(this.itemsElement, 1.0);
    } else {
      var iLeft = this.getLeft(index);
      Element.setStyle(this.itemsElement, {'left':iLeft + 'px'});
      Element.setOpacity(this.itemsElement, 1.0);
    }

    this.navScrollIndex = index;
    Element.display(this.forwardElement, this.navScrollIndex <= this.items.length - (this.setSize+1));
    Element.display(this.backElement, (parseInt(this.navScrollIndex) || 0) != 0);
  }
};

Element.addMethods({
  display: function(element, bShow){
    if (bShow) {
      Element.show(element);
    } else {
      Element.hide(element);
    }
  }
});