/*
	This is the JavaScript file for the How to Create CAPTCHA Protection using PHP and AJAX Tutorial
result
	You may use this code in your own projects as long as this 
	copyright is left in place.  All code is provided AS-IS.
	This code 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.
	
	For the rest of the code visit http://www.WebCheatSheet.com
	
	Copyright 2006 WebCheatSheet.com	

*/
//Gets the browser specific XmlHttpRequest Object 
function getXmlHttpRequestObject() {
 if (window.XMLHttpRequest) {
    return new XMLHttpRequest(); //Mozilla, Safari ...
 } else if (window.ActiveXObject) {
    return new ActiveXObject("Microsoft.XMLHTTP"); //IE
 } else {
    //Display our error message
    alert("Your browser doesn't support the XmlHttpRequest object.");
 }
}

//
//Our XmlHttpRequest object
var receiveReq = getXmlHttpRequestObject();
var myForm;
var valid="fail";

//Initiate the AJAX request
function makeRequest(url, param) 
{
	//If our readystate is either not started or finished, initiate a new request
	 //if (receiveReq.readyState == 4 || receiveReq.readyState == 0) 
	//{
	   
		   //Set up the connection to captcha_test.html. True sets the request to asyncronous(default) 
		   receiveReq.open("POST", url, true);
		   
		   receiveReq.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
		   //receiveReq.setRequestHeader("Content-length", param.length);
		   //receiveReq.setRequestHeader("Connection", "close");
		
		   //Make the request
		   receiveReq.send(param);
		   
		   //Set the function that will be called when the XmlHttpRequest objects state changes
		   receiveReq.onreadystatechange = updatePage; 
	
	   
	 //}   
}

//Called every time our XmlHttpRequest objects state changes
function updatePage() 
{
	 //Check if our response is ready
	 if (receiveReq.readyState == 4 && receiveReq.status == 200) 
	 {
	   	//Set the content of the DIV element with the response text
	   	valid=receiveReq.responseText;
	
		if (valid=="ok" )
		{
			 myForm.submit();
		}
	   	else
	   	{
	                   alert ("The text you entered does not match the security image!");
	   		   //Get a reference to CAPTCHA image
			   img = document.getElementById('imgCaptcha'); 
			   
			   //Change the image
	   			img.src = 'captcha/create_image.php?'+Math.floor(Math.random());
		}  
 }
 
}

//Called every time when form is perfomed
function getParam(theForm) 
{
	 myForm=theForm;
	 
	 //Set the URL
	 var url = 'captcha/captcha.php';
	 //Set up the parameters of our AJAX call
	 var postStr = theForm.txtCaptcha.name + "=" + encodeURIComponent( theForm.txtCaptcha.value );
	 //Call the function that initiate the AJAX request
	 makeRequest(url, postStr);
}