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.SlideUp(this.bodys[i]);
                    }
                }

                new Effect.SlideDown(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;