// ajax.js - handle background http requests for the CAPTCHA module
// copyright (c) 2007 adam@adamscottsoftware.com
// created 2007-11-28


// 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.") ; // TODO
    }
}


// Instantiate Our XmlHttpRequest object
var theXmlHttpRequestObject = getXmlHttpRequestObject() ;


// Called every time when form is perfomed
// called when the CAPTCHA form submit button is clicked.  
// initiates an HTTP POST containing the user's response to the CAPTCHA image challenge
//
function getParam( theForm )
{    
	 var changeIt = theForm.txtCaptcha.value;
	 
	 document.form1.hidden_token.value = changeIt;
	 
	 
	 
// Set the URL
//  var url = 'http://tahoepowderhouse.com/captcha.php' ;
    var url = '/captcha.php' ; // have to use relative path as XMLHTTPRequest is not affected by domain lowering

    // Add the user's response to the CAPTCHA image challenge to our HTTP POST call's parameters
    var postStr = theForm.txtCaptcha.name + "=" + encodeURIComponent( theForm.txtCaptcha.value ) ;

    // Call the function that performs the background HTTP POST call
    makeRequest( url, postStr ) ;
}

// Initiate the HTTP POST call.  Since this call is ansychronous, a callback function will be
// called when the server responds to our HTTP POST request.
//
function makeRequest( url, param )
{
  // todo: switch .status = 200
  // If our readystate is either not started or finished, initiate a new request
    if ( theXmlHttpRequestObject.readyState == 4 || theXmlHttpRequestObject.readyState == 0 ) 
    {
        // Set up the connection to captcha_test.html. True sets the request to asyncronous(default)
        theXmlHttpRequestObject.open( "POST", url, true ) ;
        // Set the function that will be called when the XmlHttpRequest objects state changes
        theXmlHttpRequestObject.onreadystatechange = updatePage ;

        // Add HTTP headers to the request
        theXmlHttpRequestObject.setRequestHeader( "Content-type", "application/x-www-form-urlencoded" ) ;
        theXmlHttpRequestObject.setRequestHeader( "Content-length", param.length ) ;
        theXmlHttpRequestObject.setRequestHeader( "Connection", "close" ) ;

        // Make the request
        theXmlHttpRequestObject.send( param ) ;
     }
}


// Callback function.  Called when the XmlHttpRequest object's state changes,
// this function is called in response to the HTTP POST request we made in makeRequest().
//
//  // TODO: a user could just rewrite this js to execute the passedCaptchaChallenge branch.
//  //       this will prevent robots, but may need to be rearchitected to effectively block humans.
//
//
function updatePage()
{
    // Check if our response is ready
    if ( theXmlHttpRequestObject.readyState == 4 )
    {
        if ( theXmlHttpRequestObject.responseText == "PASSED" )
            passedCaptchaChallenge = true ;
        else
            passedCaptchaChallenge = false ;

        if ( passedCaptchaChallenge )
        {
            // Get a reference to CAPTCHA form
            theForm = document.getElementById( 'frmCaptcha' ) ;

            // Hide the CAPTCHA form
            theForm.style.display = 'none' ;

            // Get a reference to the main form's submit buttom
            theSubButton = document.getElementById( 'main_submit' ) ;

            // Show the main form's submit button
            theSubButton.style.display = 'block' ;

            // 'click' the main form's submit button for the user
            theSubButton.click() ;  // TODO: ?get ref to form and form.submit() ;
        }

        else
        {
            // Get a reference to CAPTCHA image and change it
            img = document.getElementById( 'imgCaptcha' ) ;
            img.src = 'captcha_create.php?' + Math.random() ;
            
            // Get a reference to bad code warning DIV and show it
            warndiv = document.getElementById( 'captchaWarn' ) ;
            warndiv.style.display = 'block' ;
        }
    }
}