function postRequest(strURL){
var xmlHttp;
if(window.XMLHttpRequest){ // For Mozilla, Safari, ...
var xmlHttp = new XMLHttpRequest();
}
else if(window.ActiveXObject){ // For Internet Explorer
var xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlHttp.open('POST', strURL, true);
xmlHttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xmlHttp.onreadystatechange = function(){
if (xmlHttp.readyState == 4){
updatepage(xmlHttp.responseText);
}
}
xmlHttp.send(strURL);
}

function updatepage(str){
if(str.charAt(0)==1){
	
	
	alert("Welcome back, " + str.slice(2) + "!");
	Effect.toggle('login_form','appear');
	toggle_it('not_logged_in');
	toggle_it('logged_in_msg');
	

} else if(str.charAt(0)==2){
	alert("You have not yet activated your account!");

} else if(str.charAt(0)==3){
	alert("You have been logged out!");
	toggle_it('not_logged_in');
	toggle_it('logged_in_msg');

} else if(str.charAt(0)==0){
	alert("Invalid username/password!");
} else{
	alert("Invalid username/password!");
}

}

function call_login(){
var username = window.document.loginform.username.value;
var password = window.document.loginform.password.value;
var url = "ajax/ajax_login.php?action=login&username=" + username + "&password=" +password ;
postRequest(url);
}



function call_logout(){
var url = "ajax/ajax_login.php?action=logout";
postRequest(url);
}


 function toggle_it(itemID){
      // Toggle visibility between none and inline
      if ((document.getElementById(itemID).style.display == 'none'))
      {
        document.getElementById(itemID).style.display = 'inline';
      } else {
        document.getElementById(itemID).style.display = 'none';
      }
  }



///test 
function opacity(id, opacStart, opacEnd, millisec) { 
    //speed for each frame 
    var speed = Math.round(millisec / 100); 
    var timer = 0; 

    //determine the direction for the blending, if start and end are the same nothing happens 
    if(opacStart > opacEnd) { 
        for(i = opacStart; i >= opacEnd; i--) { 
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed)); 
            timer++; 
        } 
    } else if(opacStart < opacEnd) { 
        for(i = opacStart; i <= opacEnd; i++) 
            { 
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed)); 
            timer++; 
        } 
    } 
} 

//change the opacity for different browsers 
function changeOpac(opacity, id) { 
    var object = document.getElementById(id).style; 
    object.opacity = (opacity / 100); 
    object.MozOpacity = (opacity / 100); 
    object.KhtmlOpacity = (opacity / 100); 
    object.filter = "alpha(opacity=" + opacity + ")"; 
} 
function shiftOpacity(id, millisec) { 
    //if an element is invisible, make it visible, else make it ivisible 
    if(document.getElementById(id).style.opacity == 0) { 
        opacity(id, 0, 100, millisec); 
    } else { 
        opacity(id, 100, 0, millisec); 
    } 
}