/**
 * Ajax.js
 *
 * Collection of Scripts to allow in page communication from browser to (struts) server
 * ie can reload part instead of full page
 *
 * How to use
 * ==========
 * 1) Call retrieveURL from the relevant event on the HTML page (e.g. onclick)
 * 2) Pass the url to contact (e.g. Struts Action) and the name of the HTML form to post
 * 3) When the server responds ...
 *		 - the script loops through the response , looking for <span id="name">newContent</span>
 * 		 - each <span> tag in the *existing* document will be replaced with newContent
 *
 * NOTE: <span id="name"> is case sensitive. Name *must* follow the first quote mark and end in a quote
 *		 Everything after the first '>' mark until </span> is considered content.
 *		 Empty Sections should be in the format <span id="name"></span>
 */

//global variables
  var req;
  var which;


  /**
   * Get the contents of the URL via an Ajax call
   * url - to get content from (e.g. /struts-ajax/sampleajax.do?ask=COMMAND_NAME_1) 
   * nodeToOverWrite - when callback is made
   * nameOfFormToPost - which form values will be posted up to the server as part 
   *					of the request (can be null)
   */
  function retrieveURL(url,nameOfFormToPost) {

    //get the (form based) params to push up as part of the get request
    url=url+getFormAsString(nameOfFormToPost);

	//Validation
	if (SignUp.validate()) {
		//Hide form and display confirmation
		$('.popupForm').hide();
		$('.popupSubmited').show();
		
	    //Do the Ajax call
	    if (window.XMLHttpRequest) { // Non-IE browsers
	      req = new XMLHttpRequest();
	      req.onreadystatechange = processStateChange;
	      try {
	      	req.open("POST", url, true); //was get
	      } catch (e) {
	        alert("Problem Communicating with Server\n"+e);
	      }
	      req.send(url);
	    } else if (window.ActiveXObject) { // IE
	      req = new ActiveXObject("Microsoft.XMLHTTP");
	      if (req) {
	        req.onreadystatechange = processStateChange;
	        req.open("POST", url, true);
	        req.send(url);
	      }
	    }
	}
  }

/*
   * Set as the callback method for when XmlHttpRequest State Changes 
   * used by retrieveUrl
  */
  function processStateChange() {
  
  	  if (req.readyState == 4) { // Complete
      if (req.status == 200) { // OK response
        
        //alert("Ajax response:"+req.responseText);
        
        //Split the text response into Span elements
        spanElements = splitTextIntoSpan(req.responseText);
        
        //Use these span elements to update the page
        replaceExistingWithNewHtml(spanElements);
        
      } else {
        alert("Problem with server response:\n " + req.statusText);
      }
    }
  }
 
 /**
  * gets the contents of the form as a URL encoded String
  * suitable for appending to a url
  * @param formName to encode
  * @return string with encoded form values , beings with &
  */ 
 function getFormAsString(formName){
 	
 	//Setup the return String
 	returnString ="";
 	
  	//Get the form values
 	formElements=document.forms[formName].elements;
 	
 	//loop through the array , building up the url
 	//in the form /strutsaction.do&name=value
 	
 	for ( var i=formElements.length-1; i>=0; --i ){
 		//we escape (encode) each value
 		returnString=escape(formElements[i].name)+"="+escape(formElements[i].value)+"&"+returnString;
 	}
 	returnString="?"+returnString;
 	
 	//return the values
 	return returnString; 
 }
 
 /**
 * Splits the text into <span> elements
 * @param the text to be parsed
 * @return array of <span> elements - this array can contain nulls
 */
 function splitTextIntoSpan(textToSplit){
 
  	//Split the document
 	returnElements=textToSplit.split("</span>")
 	
 	//Process each of the elements 	
 	for ( var i=returnElements.length-1; i>=0; --i ){
 		
 		//Remove everything before the 1st span
 		spanPos = returnElements[i].indexOf("<span");		
 		
 		//if we find a match , take out everything before the span
 		if(spanPos>0){
 			subString=returnElements[i].substring(spanPos);
 			returnElements[i]=subString;
 		
 		} 
 	}
 	
 	return returnElements;
 }
 
 /*
  * Replace html elements in the existing (ie viewable document)
  * with new elements (from the ajax requested document)
  * WHERE they have the same name AND are <span> elements
  * @param newTextElements (output of splitTextIntoSpan)
  *					in the format <span id=name>texttoupdate
  */
 function replaceExistingWithNewHtml(newTextElements){
 
 	//loop through newTextElements
 	for ( var i=newTextElements.length-1; i>=0; --i ){
  
 		//check that this begins with <span
 		if(newTextElements[i].indexOf("<span")>-1){
 			
 			//get the name - between the 1st and 2nd quote mark
 			startNamePos=newTextElements[i].indexOf('"')+1;
 			endNamePos=newTextElements[i].indexOf('"',startNamePos);
 			name=newTextElements[i].substring(startNamePos,endNamePos);
 			
 			//get the content - everything after the first > mark
 			startContentPos=newTextElements[i].indexOf('>')+1;
 			content=newTextElements[i].substring(startContentPos);
 			
 			//Now update the existing Document with this element
 			
	 			//check that this element exists in the document
	 			if(document.getElementById(name)){
	 			
	 				//alert("Replacing Element:"+name);
	 				document.getElementById(name).innerHTML = content;
	 			} else {
	 				//alert("Element:"+name+"not found in existing document");
	 			}
 		}
 	}
 }

var SignUp = {
	validate: function() {
		var isValid = true;

		if (SignUp.isEmpty('teacher.firstName')) {
			document.getElementById('firstNameError').innerHTML = "First?";
			isValid = false;
		} else {
			document.getElementById('firstNameError').innerHTML = "";
		}

		if (SignUp.isEmpty('teacher.lastName')) {
			document.getElementById('lastNameError').innerHTML = "Last?";
			isValid = false; 
		} else {
			document.getElementById('lastNameError').innerHTML = "";
		}

		if (SignUp.isEmpty('teacher.email')) {
			document.getElementById('emailError').innerHTML = "Email?";
			isValid = false; 
		} else if (SignUp.isInvalidEmail('teacher.email')) {
			document.getElementById('emailError').innerHTML = "Email?";
			isValid = false; 
		} else {
			document.getElementById('emailError').innerHTML = "";
		}

		if (SignUp.isEmpty('teacher.title')) {
			document.getElementById('titleError').innerHTML = "Title?";
			isValid = false; 
		} else {
			document.getElementById('titleError').innerHTML = "";
		}

		if (SignUp.isEmpty('teacher.schoolName')) {
			document.getElementById('schoolNameError').innerHTML = "District?";
			isValid = false; 
		} else {
			document.getElementById('schoolNameError').innerHTML = "";
		}

		if (SignUp.isEmpty('teacher.state')) {
			document.getElementById('stateError').innerHTML = "State?";
			isValid = false; 
		} else {
			document.getElementById('stateError').innerHTML = "";
		}

		return isValid; 
	}, 
	
	isEmpty: function(field) {
		var fieldValue;
		field = document.getElementById(field);
		fieldValue = field.value;
		return fieldValue.length == 0; 
	}, 
	
	isInvalidEmail: function(field) {
		field = document.getElementById(field);
		var filter = /^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i;
		return !filter.test(field.value);
	}
}