/**
*    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')
                }, 
                // tc : added so that can change the value to send if I need to
                valueToSend: function(element){
                    return $(element).val();
                }
            } , settings);

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

            if (settings.before != null){
                // tc: have made it so that if the before function returns false then
                // do nothing, this helps prevent making unneeded calls to the server
                var tempValue = settings.before( target )
                console.log("should make next request : " + tempValue)
                if (settings.before( target ) == false){
                    return;
                }
            }

            var ajaxCallback = function(data, textStatus){
                $(target).html("");//clear old options
                data = eval(data);//get json array
                for (var i = 0; i < data.length; i++)//iterate over all options
                {
                    for (var 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 );
            }


        });
    });
};