/*------------------------------------------------------------------------------
 * bAjax - A tiny Ajax library
 * Version 1.0.1
 * by Boris Ding P H, http://bajax.borisding.com
 * Copyright (c) 2009 Boris Ding P H. All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *------------------------------------------------------------------------------
 */  

var bajax = (function(){
	var action = {
		// star implementing ajax
		init: function(option){
			attr = option;
			
			//this.checkId();
			this.checkURL();
			this.initAjax();
		},// end init
		
		// check for id
		/*	checkId: function(){
			//check if id is empty, null or undefined
			if(typeof attr.id == "undefined"){
				alert(error.e000);
				return false;
			}else if(attr.id == null || attr.id ==""){
				alert(error.e001);
				return false;
			}		
		},*/
		
		//check for url
		checkURL: function(){
			if(typeof attr.url == "undefined"){
				alert(error.e002);
				return false;
			}else if(attr.url == null || attr.url ==""){
				alert(error.e003);
				return false;
			}				
		},
		
		// filter data
		filteredData: function(){
			var data;
			if(typeof attr.data != "undefined"){
				if(attr.data != ""){
					data = attr.data + "&rid=" + Math.random(); 	
				}else{
					data = "rid=" + Math.random();	
				}
			//else undefined	 
			}else{
				data = "rid=" + Math.random();	 
			}
			return data;	
		},
		
		//check for type
		checkType: function(){
			var type;
			
			switch(attr.type){
				case "xml":
				case "json":
				return attr.type;
				break;
				
				default:
				return "text";		 
			}//end switch
		},
		
		// implementing post method
		postMethod: function(){
			var url =  attr.url;
			var data = this.filteredData();
			xhr.open("POST", url, true);
			xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
			xhr.send(data);
		},
		
		// implementing get method
		getMethod: function(){
			var url =  attr.url + "?" + this.filteredData();
			
			// if xml
			if(this.checkType() == "xml"){
				if(xhr.overrideMimeType){
					xhr.overrideMimeType("text/xml");
				}
			}
			
			xhr.open("GET", url, true);
			xhr.send(null);
		},
		
		// fetch result from the server	 
		retrieveResult: function(){
			if(xhr.readyState == 4){
			
				if(xhr.status == 404){
					alert(error.e404);	  
				}
				
				if(xhr.status == 408){
					alert(error.e408);	  
				}
				
				if(xhr.status == 200 || xhr.status == 304){
					var responseData;
					
					// xml data
					if(typeof attr.type != "undefined" && bajax.checkType() == "xml"){
						responseData = xhr.responseXML;
						
						// json data
					}else if(typeof attr.type != "undefined" && bajax.checkType() == "json"){         
						responseData = eval("(" + xhr.responseText + ")");  
					}
					
					// plain text
					else{
						responseData = xhr.responseText;
					}
					
					// simple_display_into  - the id of the element where to simply display the response
					if(attr.simple_display_into){
						element = document.getElementById(attr.simple_display_into);
						if(element != null){
							element.innerHTML = responseData;
						}
					}
					
					if(attr.callback){
						attr.callback(responseData);
					}
				}	  
			}// end if complete	 
		},
		
		// decide which method to use
		decideMethod: function(){
			xhr.onreadystatechange = this.retrieveResult;
			
			if(typeof attr.method != "undefined"){
				switch(attr.method){
					//send data with POST method  
					case "POST":
					this.postMethod();
					break;
					
					default:
					// send data with GET method, by default
					this.getMethod();
				}//end switch	   
			}else{
				// send to server with GET method if not specified
				this.getMethod();	 
			}
		},
		
		//init ajax
		initAjax: function(){
			xhr = this.	createXHR();
			// check for xhr object
			if(xhr == null){
				alert(error.eoo4);
				return false;
			}else if(xhr.readyState != 0){
				xhr.abort();	
			}
			this.decideMethod(); 	
		},
		
		//creating XMLHttpRequest object
		createXHR: function(){
			var XHR = null;
			if(typeof XMLHttpRequest != "undefined"){
				XHR = new XMLHttpRequest();
				return XHR;
			}else if(window.ActiveXObject){
				var arrayMSXml = ["MSXML2.XMLHttp.6.0", "MSXML2.XMLHttp.3.0"];
				var i = 0;
				var lengthMSXml = arrayMSXml.length;
				
				while(i < lengthMSXml){
					try{
						XHR = new ActiveXObject(arrayMSXml[i]);
						return XHR;
					}catch(xhrError){}
					i++;
				}//end while
			}//end else
			throw new Error("Failed to create XHR object!");
		},// end createXHR
		
		//Manipulate ajax loader
		//------------------------------------------------------------
		loader: function(tagID, loader){
			document.getElementById(tagID).innerHTML = loader;	
		},
		
		clearLoader: function(tagID){
			document.getElementById(tagID).innerHTML = "";		
		},
		
		//Manipulate form data (serialization)
		//------------------------------------------------------------
		serialized: function(formId){
			var arrayInput = Array();
			
			var form = document.getElementById(formId);
			// check form element type, accordingly
			
			var i = 0; 
			while(i < form.elements.length){
				var field = form.elements[i];
				
				switch(field.type){
					// if button, submit, reset
					case "button":
					case "submit":
					case "reset":
					break; // buttons, do nothing
					
					// if text, hidden, password
					case "text":
					case "hidden":
					case "password":	 
					arrayInput.push(this.encodeValue(field.name, field.value));
					break;
					
					// if radio, checkbox
					case "radio":
					case "checkbox":
					if(!field.checked){
						break;
					}
					
					default: //the rest, such as select
					if(field.type == "select-one"){
						arrayInput.push(this.encodeValue(field.name, field.options[field.selectedIndex].value));
					}else if(field.type == "select-multiple"){
						// if multiple, check selected and push into array
						var mSn = 0;
						for(var j = 0; j < form.elements[field.name].length; j++){
							if(form.elements[field.name].options[j].selected == true){
								mSn++;
								var mName = field.name + mSn;	 
								arrayInput.push(this.encodeValue(mName, form.elements[field.name].options[j].value));
							}
						}//end for	   
					}else{ // collect radio and checkbox
						arrayInput.push(this.encodeValue(field.name, field.value));
					}		
				}//end switch
				i++;
			}// end while
			return arrayInput.join("&");		
		},//end serialize
		
		encodeValue: function(name, val){
			var input = encodeURIComponent(name);
			
			input += "=";
			input += encodeURIComponent(val);
			
			return input;
		}
	};
	
	return action;
})();

// compiled error messages
var error = {
	e404: "ERROR 404: Page was not found!",
	e408: "ERROR 408: Request Timeout! Please try again.",
	
	e000: "ERROR: 'id' is undefined!",
	e001: "ERROR: 'id' is null or empty!",
	
	e002: "ERROR: 'url' is undefined!",
	e003: "ERROR: 'url' is null or empty!",
	
	eoo4: "ERROR: Your browser does not support XHR object!"
};

// global variables
var attr = null;
var xhr = null;