var AACaching = false;


function AACreate() 
{
    var request = false;
        try {
            request = new ActiveXObject('Msxml2.XMLHTTP');
        }
        catch (err2) {
            try {
                request = new ActiveXObject('Microsoft.XMLHTTP');
            }
            catch (err3) {
        try {
            request = new XMLHttpRequest();
        }
        catch (err1) 
        {
            request = false;
        }
        }
    }
    return request;
}


/**
    AA Read
    Load a file, text or XML
*/    

function AARead(url, fun, element)
{ 
    var xhr = AACreate();
    var ext = url.substr(url.length - 3);
    var isXML =  (ext == "xml");    

    xhr.onreadystatechange=function()
    { 
        if(xhr.readyState == 4)
        {
            if(xhr.status == 200)
            {
                var content;
                if(isXML) 
                    content = xhr.responseXML;
                else
                    content = xhr.responseText;
                fun(content, element);
            }
        } 
    }; 

    if(AACaching == false)
        url = url + "&nocache=" + Math.random();
    xhr.open("GET", url , true);
    xhr.send(null); 
} 

/**
    Read an XML file with any extension
*/

function AALoadXML(url, fun, element)
{ 
    var xhr = AACreate();
    xhr.onreadystatechange=function()
    { 
        if(xhr.readyState == 4)
        {
            fun(xhr.responseXML, element);
        } 
    }; 
    xhr.open("GET", url , true);
    xhr.send(null); 
} 

/**
    AAWrite
    url:    the script
    data:    the string to pass to the script
        it is a list of pairs x=y separated by &
*/    

function AAWrite(url, data, fun)
{ 
    var xhr = AACreate();

    xhr.onreadystatechange=function()
    { 
        if(xhr.readyState == 4)
        {
            if(fun != null) fun();
        }
    }; 
    xhr.open("POST", url, true);        
    xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    xhr.send(data); 
} 
    

function AAGetBody(content)
{
    var x = content.indexOf("<body");
    if(x == -1) return "";
        
    x = content.indexOf(">", x);
    if(x == -1) return "";

    var y = content.lastIndexOf("</body>");
    if(y == -1) return "";
    
    return content.slice(x + 1, y);
}

function AAPutHTML(content, target)
{
    target.innerHTML = AAGetBody(content);
}

/**
    Loads a HTML page
    Put the content of the body tag into the current page.
    Arguments:
        url of the other HTML page to load
        id of the tag that has to hold the content
*/        

function AALoadHTML(url, fun, storage, param)
{
    var xhr = AACreate();
    xhr.onreadystatechange=function()
    { 
        if(xhr.readyState == 4)
        {
            if(xhr.status == 200)
            {
                storage = document.getElementById(storage);
                storage.innerHTML = AAGetBody(xhr.responseText);
                fun(storage, param);
            }
        } 
    }; 

    if(AACaching == false)
        url = url + "?nocache=" + Math.random();
    xhr.open("GET", url , true);
    xhr.send(null); 

} 


/**
    Send a HEAD request,
    call a function with the value 
*/

function AAHead(url, key, fun, element)
{ 
    var xhr = AACreate();

    xhr.onreadystatechange = function() 
    {
        if(xhr.readyState == 4) 
        {
            var value;
            if (xhr.status == 200)
            { 
                 value = xhr.getResponseHeader(key);
            }
            else 
            {
                if(xhr.status==404) 
                    value = url + " doesn't exist!";
                else 
                    value = "Error, status is " + xhr.status;
            }
            fun(value, element);        
        }
    }
    xhr.open("HEAD", url, true);
    xhr.send(null); 
}