/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

var Slides = Class.create({

    initialize: function(element, options) {        
        this.options = {
              Duration: 1,
            Delay: 10.0,
            Random: true,
            Slideshow:true,
            Controls:true
        }
        Object.extend(this.options, options || {});

        this.element        = $(element);
        this.slides            = this.element.childElements();
        this.num_slides        = this.slides.length;        
        this.current_slide     = (this.options.Random) ? (Math.floor(Math.random()*this.num_slides)) : 0;
        this.end_slide        = this.num_slides - 1;

        if(this.num_slides > 1) {
            this.slides.invoke('hide');
            this.slides[this.current_slide].show();

            if (this.options.Slideshow) {
                this.startSlideshow();
            }
            if (this.options.Controls) {
                this.addControls();
            }
        }
    },
    
    addControls: function() {
        this.btn_previous    = $('previous');
        this.btn_next         = $('next');
        this.btn_start        = $('start');
        this.btn_stop        = $('stop');
        
        this.btn_previous.observe('click', this.moveToPrevious.bindAsEventListener(this));
        this.btn_next.observe('click', this.moveToNext.bindAsEventListener(this));
        this.btn_start.observe('click', this.startSlideshow.bindAsEventListener(this));
        this.btn_stop.observe('click', this.stopSlideshow.bindAsEventListener(this));
    },

    startSlideshow: function(event) {
        if (event) { Event.stop(event); }
        if (!this.running)    {
            this.fadeStartBtn();
            this.executer = new PeriodicalExecuter(function(){
                  this.updateSlide(this.current_slide+1);
             }.bind(this),this.options.Delay);
            this.running=true;
        }
        
    },
    
    fadeStartBtn: function() {
        var startBtn = $('start');
        var stopBtn = $('stop');
        Effect.Fade(startBtn, { duration: 0.3 }),
        Effect.Appear(stopBtn, { duration: 0.3 }) 
    },
    
    stopSlideshow: function(event) {    
        if (event) { Event.stop(event); } 
        if (this.executer) {
            this.fadeStopBtn();
            this.executer.stop();
            this.running=false;
        }     
    },
    
    fadeStopBtn: function() {
        var startBtn = $('start');
        var stopBtn = $('stop');
        Effect.Fade(stopBtn, { duration: 0.3 }),
        Effect.Appear(startBtn, { duration: 0.3 }) 
    },

    moveToPrevious: function (event) {
        if (event) { Event.stop(event); }
        //this.stopSlideshow();
          this.updateSlide(this.current_slide-1);
    },

    moveToNext: function (event) {
        if (event) { Event.stop(event); }
        //this.stopSlideshow();
          this.updateSlide(this.current_slide+1);
    },
    
    updateSlide: function(next_slide) {
        if (next_slide > this.end_slide) { 
                next_slide = 0; 
        } 
        else if ( next_slide == -1 ) {
                next_slide = this.end_slide;
        }
        
        this.fadeInOut(next_slide, this.current_slide);        
    },

     fadeInOut: function (next, current) {        
        new Effect.Parallel([
            new Effect.Fade(this.slides[current], { sync: true }),
            new Effect.Appear(this.slides[next], { sync: true }) 
          ], { duration: this.options.Duration });
        
        this.current_slide = next;        
    }

});