/**
*    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).each(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);//get json array
				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 );
			}
		});
		$(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);//get json array
				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 );
			}
		});

	});
};