// 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

// site: http://prototype-carousel.xilinus.com/

var Carousel = Class.create();
Carousel.prototype = {
// 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 = document.getElementsByClassName(carouselListClass, $(carouselElemID))[0];
		this.options.size =  $(this.carouselList.immediateDescendants()).length;
		// 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;
		
		// Ajax content
		if (this.options.url)
			this._request(this.currentIndex, this.options.numVisible);
		// Static content
		else {
			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)
			return;
		
		var inc = this.options.scrollInc;
		
		if (this.currentIndex - inc < 0)
			inc = this.currentIndex;
		
		this._scroll(inc)		  
		return false;
	},
	
	_nextScroll: function(event) {    
		if (this.animRunning != "none")
		return false;
		
		// 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);
			}
		}
		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.immediateDescendants().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;
		}
		// Add images
		else {
			if (!this.ignoreNoMoreImages)
				this.noMoreImages = inc != this.options.scrollInc;
			else
				this.ignoreNoMoreImages = false;
		// Add images
		if (inc > 0) {
			this._scroll(-inc, this.noMoreImages);
		}
		// No more images, disable next button
		else {
			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);
		
		new Effect.MoveBy(this.carouselList, 0, delta * this.elementSize, this.options.animParameters);
		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.immediateDescendants()[0]);
		this.elementSize = li.getDimensions().width + parseFloat(li.getStyle("margin-left")) + parseFloat(li.getStyle("margin-right"));
	}
}