/**
*    Chained Selects for jQuery 
*    Copyright (C) 2008 Ziadin Givan www.CodeAssembly.com  
*
*    This program is free software: you can redistribute it and/or modify
*    it under the terms of the GNU General Public License as published by
*    the Free Software Foundation, either version 3 of the License, or
*    (at your option) any later version.
*
*    This program is distributed in the hope that it will be useful,
*    but WITHOUT ANY WARRANTY; without even the implied warranty of
*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*    GNU General Public License for more details.
*
*    You should have received a copy of the GNU General Public License
*    along with this program.  If not, see http://www.gnu.org/licenses/
*
*    
*   settings = { usePost : true, before:function() {}, after: function() {}, default: null, parameters : { parameter1 : 'value1', parameter2 : 'value2'} }	
*   if usePost is true, then the form will use POST to pass the parameters to the target, otherwise will use GET
*   "before" function is called before the ajax request and "after" function is called after the ajax request.
*   If defaultValue is not null then the specified option will be selected.
*   You can specify additional parameters to be sent to the the server in settings.parameters.
*
*/
jQuery.fn.chainSelect = function($, target, url, settings) {
    return this.each(function() {
        $(this).change(function() {
            settings = jQuery.extend(
		{
		    after: null,
		    before: null,
		    usePost: false,
		    defaultValue: null,
		    parameters: { '_id': $(this).attr('id'), '_name': $(this).attr('name') }
		}, settings);

            settings.parameters._value = $(this).val();

            if (settings.before != null) {
                settings.before(target);
            }

            ajaxCallback = function(data, textStatus) {
                $(target).html(""); //clear old options
                data = eval(data);
                for (i = 0; i < data.length; i++)//iterate over all options
                {
                    for (key in data[i])//get key => value
                    {
                        $(target).get(0).add(new Option(data[i][key], [key]), document.all ? i : null);
                    }
                }

                if (settings.defaultValue != null) {
                    $(target).val(settings.defaultValue); //select default value
                } else {
                    $("option:first", target).attr("selected", "selected"); //select first option
                }

                if (settings.after != null) {
                    settings.after(target);
                }

                $(target).change(); //call next chain
            };

            if (settings.usePost == true) {
                $.post(url, settings.parameters, ajaxCallback);
            } else {
                $.get(url, settings.parameters, ajaxCallback);
            }
        });
    });
};