// 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 Carousel = Class.create();
Carousel.prototype = {
    // Constructor
    initialize: function(carouselElemID) {
        this.carouselElemID = carouselElemID;

        this.options = Object.extend({
            //numVisible: 4,
	    	numVisible: 3,
            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-vertical";
        this.carouselList = document.getElementsByClassName(carouselListClass, $(carouselElemID))[0];
        this.options.size =  $(this.carouselList.getElementsByTagName("li")).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.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
        }
        // 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, delta * this.elementSize, 0, 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.getElementsByTagName("li")[0]);
        // -- the following line is for horizontal scrolling
        //this.elementSize = li.getDimensions().width + parseFloat(li.getStyle("margin-left")) + parseFloat(li.getStyle("margin-right")) + -8;
        // -- the following line is for vertical scrolling
        this.elementSize = li.getDimensions().height + parseFloat(li.getStyle("margin-top")) + parseFloat(li.getStyle("margin-bottom"));
    }
}