var Accordion = Class.create(); 

Accordion.prototype = 
{ 
    initialize: function(handles, bodys, options) 
    { 
        this.options = this._set_options(options);         
        this.headers = $$(handles); 
        this.bodys = $$(bodys); 
         
        if(this.bodys.length != this.headers.length) 
        { 
            throw Error('Number of headers/bodys does not match!'); 
        } 
         
        for(var i = 0; i < this.headers.length; i++) 
        {         
            Event.observe(this.headers[i], this.options.event_trigger, this.show.bind(this, i)); 
             
            this.bodys[i].style.display = "none"; 
        } 
         
        this.bodys[this.options.default_open].id = "visible"; 
         
        this.show(this.options.default_open, true); 
    }, 

    show: function(index, force) 
    {         
        if ((index >= this.length) || (index < 0)) 
        { 
            throw Error('Index out of range'); 
        } 
         
        if (this.bodys[index].id == 'visible') 
        {                                  
            if (typeof force == "boolean") 
            {                         
                this.options.OnStart(index, this.bodys[index]); 
                                 
                // Force display the visible object                 
                for(var i = 0; i < this.bodys.length; i++) 
                { 
                    if(this.bodys[i].style.display != 'none' && i != index) 
                    { 
                        new Effect.BlindUp(this.bodys[i]); 
                    } 
                } 
                 
                new Effect.BlindDown(this.bodys[index]); 
            } 
        } 
        else 
        {         
            this.options.OnStart(index, this.bodys[index]); 
                         
            // Normal change 
            new Effect.Parallel( 
                [ 
                    new Effect.Fade($('visible')),                 
                    new Effect.BlindUp($('visible')), 
                    new Effect.BlindDown(this.bodys[index]), 
                    new Effect.Appear(this.bodys[index]) 
                ], { 
                    duration: this.options.duration 
                } 
            ); 
     
            $('visible').id = ""; 
            this.bodys[index].id = "visible"; 
        } 
         
        this.options.OnFinish(index, this.bodys[index]); 
    }, 
     
    _default_options: 
    { 
        duration: 0.3,         
        default_open: 0, 
        event_trigger: 'click', 
        OnStart: function() { }, 
        OnFinish: function() { } 
    }, 
     
    _set_options: function(options) 
    { 
        if(typeof options != "undefined") 
        {         
            var result = []; 
            for(option in this._default_options) 
            { 
                if(typeof options[option] == "undefined") 
                { 
                    result[option] = this._default_options[option]; 
                } 
                else 
                { 
                    result[option] = options[option]; 
                } 
            } 
         
            return result; 
        } 
        else 
        { 
            return this._default_options; 
        } 
    }         
}; 

Effect.Accordion = Accordion;