// Copyright (c) 2006 Sébastien Gruhier (http://xilinus.com, http://itseb.com)
// 
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// VERSION 0.26

var VCarousel = Class.create(
{
    // Constructor
    initialize: function(carouselElemID)
    {
        this.carouselElemID = carouselElemID;

        this.options = Object.extend(
        {
            numVisible:           4,
            scrollInc:            3,
            animParameters:      {},
            buttonStateHandler:  null,
            animHandler:         null,
            ajaxHandler:         null,
            initDoneHandler:     null,
            queue:               "carousel",
            size:                0,
            prevElementID:       "prev-arrow",
            nextElementID:       "next-arrow",
            ajaxParameters:      null,
            url:                 null
        }, arguments[1] || {});

        this.initDone = false;
        this.animRunning = "none";
        this.requestIsRunning = false;
    
		// add afterFinish options to animParameters (store old function)
		this.animAfterFinish = this.options.animParameters.afterFinish;
		
		Object.extend(this.options.animParameters, {
			afterFinish: this._animDone.bind(this), 
			queue: { 
				position:'end', 
				scope: this.options.queue 
			}
		});
	  
		// Event bindings
		this.prevScroll = this._prevScroll.bindAsEventListener(this);
		this.nextScroll = this._nextScroll.bindAsEventListener(this);
		this.onComplete = this._onComplete.bindAsEventListener(this);
		this.onFailure = this._onFailure.bindAsEventListener(this);

		Event.observe(this.options.prevElementID, "click", this.prevScroll);
		Event.observe(this.options.nextElementID, "click", this.nextScroll);
		
		// Get DOM UL element
		var carouselListClass = "carousel-list";
		this.carouselList = $(carouselElemID).getElementsByClassName(carouselListClass)[0];
		
		// Init data
		this._init();
    },

    // Destructor
 	destroy: function()
 	{
        Event.stopObserving(this.options.prevElementID, "click", this.prevScroll);
        Event.stopObserving(this.options.nextElementID, "click", this.nextScroll);
	},
	
	scrollTo: function(newStart)
	{
		var old_inc = this.options.scrollInc;
		this.ignoreNoMoreImages = true;
		
		if(newStart > this.currentIndex)
		{
			this.options.scrollInc = newStart - this.currentIndex;
			this._nextScroll(this);
		}
		else
		{
            this.options.scrollInc = this.currentIndex - newStart;
            this._prevScroll(this);
		}
		
        this.options.scrollInc = old_inc;
	},
	
    /* "Private" functions */
    _init: function()
    {
        this.currentIndex = 0;
		this.options.size =  $(this.carouselList.getElementsByTagName("li")).length;
        
        if (this.options.url) // Ajax content
            this._request(this.currentIndex, this.options.numVisible);
        else // Static content
        {
            this._getLiElementSize();
            this._updateButtonStateHandler(this.options.prevElementID, false);
            this._updateButtonStateHandler(this.options.nextElementID, this.options.size > this.options.numVisible);
        }
    },
    
    _prevScroll: function(event)
    {
        if (this.animRunning != "none" || this.currentIndex == 0)
        {
        	Event.stop(event);
        	return;
        }  
        
        var inc = this.options.scrollInc;
        
        if (this.currentIndex - inc < 0)
            inc = this.currentIndex;
        
        this._scroll(inc)
        
        Event.stop(event);
        return false;
    },

    _nextScroll: function(event)
    {
        if (this.animRunning != "none")
        {
        	Event.stop(event);
        	return;
        }
        
        // Check if there are enough elements in cache
        if (this.currentIndex + this.options.numVisible + this.options.scrollInc <= this.options.size)
        {
        	 this._scroll(-this.options.scrollInc);
        }
        else
        {
            // Compute how many are in the cache
            this.nbInCache = this.options.size - (this.currentIndex + this.options.numVisible);
            if (this.options.url && this.noMoreImages == false) 
                this._request(this.currentIndex + this.options.numVisible + this.nbInCache, this.options.scrollInc - this.nbInCache);
            else 
            {
                if (this.nbInCache > 0)
                    this._scroll(-this.nbInCache);
            }
        }
        
        Event.stop(event);
        return false;
    },

    _request: function(start, nb)
    {
        if (this.options.url && ! this.requestIsRunning)
        {
            this.requestIsRunning = true;
      
            if (this.options.ajaxHandler)
                this.options.ajaxHandler(this, "before");
            
            var params = "start=" + start + "&nb=" + nb;
            if (this.options.ajaxParameters != null)
                params += "&" + this.options.ajaxParameters
            new Ajax.Request(this.options.url, {parameters: params, onComplete: this.onComplete, onFailure: this.onFailure});
        }
    },
    
    _onComplete: function(originalRequest)
    {
        this.requestIsRunning = false;
        this.carouselList.innerHTML += originalRequest.responseText;
        // Compute how many new elements we have
        var size = this.options.size;
        this.options.size = this.carouselList.getElementsByTagName("li").length;
        var inc = this.options.size - size;
    
		// First run, compute li size
		if (this.initDone == false)
		{
  		    this._getLiElementSize();
            this.currentIndex = 0;
            this.initDone = true;
            if (this.options.initDoneHandler) 
                this.options.initDoneHandler(this);
            // Update button states
            this._updateButtonStateHandler(this.options.prevElementID, false);
            this._updateButtonStateHandler(this.options.nextElementID, this.options.size == this.options.numVisible);
            this.noMoreImages = this.options.size < this.options.numVisible
		}
		else // Add images
		{
		    if (!this.ignoreNoMoreImages)
                this.noMoreImages = inc != this.options.scrollInc;
            else
                this.ignoreNoMoreImages = false;
            // Add images
            if (inc > 0)
            {
                this._scroll(-inc, this.noMoreImages)
            }
            else // No more images, disable next button
            {
                if (this.nbInCache >0)
                    this._scroll(-this.nbInCache, true);
                this._updateButtonStateHandler(this.options.nextElementID, false);
            }
        }
        if (this.options.ajaxHandler)
            this.options.ajaxHandler(this, "after");
    },
    
    _onFailure: function(originalRequest)
    {
        this.requestIsRunning = false;
    },

    _animDone: function(event)
    {
        if (this.options.animHandler)
            this.options.animHandler(this.carouselElemID, "after", this.animRunning);
            
        this.animRunning = "none";
        
        // Call animAfterFinish if exists
        if (this.animAfterFinish)
            this.animAfterFinish(event);
    },

    _updateButtonStateHandler: function(button, state)
    {
        if (this.options.buttonStateHandler) 
            this.options.buttonStateHandler(button, state)
    },
    
    _scroll: function(delta, forceDisableNext)
    {
        this.animRunning = delta > 0 ? "prev" : "next";
        
        if (this.options.animHandler)
            this.options.animHandler(this.carouselElemID, "before", this.animRunning);
        
        var mt = this.carouselList.getStyle('marginTop');
        mt = parseInt(mt.substr(0, mt.length-2));
        mt = (mt + (delta*this.elementSize)) + 'px';
        
        var o = Object.extend({style: {marginTop: mt}}, this.options.animParameters);
        
        new Effect.Morph(this.carouselList, o);
        	
        this.currentIndex -= delta;
        this._updateButtonStateHandler(this.options.prevElementID, this.currentIndex != 0);
        
        if (this.options.url && this.noMoreImages == false)
            enable = true;
        else
            enable = (this.currentIndex + this.options.numVisible < this.options.size);
            
        this._updateButtonStateHandler(this.options.nextElementID, (forceDisableNext ? false : enable));
    },
    
    _getLiElementSize: function()
    {
        var li = $(this.carouselList.getElementsByTagName("li")[0]);
		this.elementSize = li.getDimensions().height + parseFloat(li.getStyle("marginTop")) + parseFloat(li.getStyle("marginBottom"));
    }
});