// stores the reference to the XMLHttpRequest object
var xmlHttp = createXmlHttpRequestObject(); 

// retrieves the XMLHttpRequest object
function createXmlHttpRequestObject() 
{	
  // will store the reference to the XMLHttpRequest object
  var xmlHttp;
  // if running Internet Explorer
  if(window.ActiveXObject)
  {
    try
    {
      xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    catch (e) 
    {
      xmlHttp = false;
    }
  }
  // if running Mozilla or other browsers
  else
  {
    try 
    {
      xmlHttp = new XMLHttpRequest();
    }
    catch (e) 
    {
      xmlHttp = false;
    }
  }
  // return the created object or display an error message
  if (!xmlHttp)
 	{
    	alert("Please update your browser to use this feature.");
		window.location.href = history.back();
	}
  else 
    return xmlHttp;
}

// make asynchronous HTTP request using the XMLHttpRequest object 
function process(task)
{
  // proceed only if the xmlHttp object isn't busy
  if (xmlHttp.readyState == 4 || xmlHttp.readyState == 0)
  {
    // retrieve the name typed by the user on the form
    agencyID      = encodeURIComponent(document.getElementById("agencyID").value);
    coursesID     = encodeURIComponent(document.getElementById("coursesID").value);
    coursedateID  = encodeURIComponent(document.getElementById("coursedateID").value);
	name 		  = encodeURIComponent(document.getElementById("name").value);
	email		  = encodeURIComponent(document.getElementById("email").value);
	comment 	  = encodeURIComponent(document.getElementById("comment").value);
	
	if ((task < 3) && (task != undefined)) { coursedateID = ''; }
	if ((task < 2) && (task != undefined)) { coursesID = ''; }
	
	// Replace the window contents
	  document.getElementById("commentform").innerHTML = 
                                            "<p>Please wait...</p>";	
    // execute the quickstart.php page from the server
    xmlHttp.open("GET", "./code/ajax_comments.php?agencyID=" + agencyID + "&coursesID=" + coursesID +"&coursedateID=" + coursedateID + "&name=" + name + "&email=" + email + "&comment=" + comment, true);  
    // define the method to handle server responses
    xmlHttp.onreadystatechange = handleServerResponse;
    // make the server request
    xmlHttp.send(null);
  }
  else
    // if the connection is busy, try again after one second  
    setTimeout('process()', 1000);
}

// executed automatically when a message is received from the server
function handleServerResponse() 
{
  // move forward only if the transaction has completed
  if (xmlHttp.readyState == 4) 
  {
    // status of 200 indicates the transaction completed successfully
    if (xmlHttp.status == 200) 
    {
      // extract the XML retrieved from the server
      xmlResponse = xmlHttp.responseXML;
      // obtain the document element (the root element) of the XML structure
      xmlDocumentElement = xmlResponse.documentElement;
      // get the text message, which is in the first child of
      // the the document element
      commentFormHTML = xmlDocumentElement.firstChild.data;
	  
	  if (commentFormHTML == "done") 
	  {	// Comment posting has completed sucessfully so let the user know
		 document.getElementById("commentform").innerHTML = '<p style=\"font-weight:bold;\">Thank you for your comment. We will hopefully see you again soon!!</p>'; 
		 alert("Thank you for your comment.\n\nWe will hopefully see you again soon!!");
	  } else
	  {
      	// update the client display using the data received from the serve$r
      	document.getElementById("commentform").innerHTML = 
                                            commentFormHTML;
	  }
    } 
    // a HTTP status different than 200 signals an error
    else 
    {
      alert("There was a problem accessing the server: " + xmlHttp.statusText);
    }
  }
}