var fileno = 0;
var filecount = 0;

function AddUpload()
{
    fileno++;
    sp = document.createElement("span");
    sp.id = "span"+fileno;
    sp.innerHTML = '<input type="file" name="file'+fileno+'" id="file'+fileno+'" style="margin: 1px" size="50" onchange="CheckFileType('+fileno+')" /> <a href="javascript:RemoveUpload('+fileno+')">remove</a><br />';
    document.getElementById("uploads").appendChild(sp);
    document.getElementById("uploads").style.display = "";
    document.getElementById("AddFile").innerHTML = "Add another photo   ";
    filecount++;
}

function RemoveUpload(fileno)
{
    document.getElementById("span"+fileno).innerHTML = "";
    filecount--;

    if (filecount == 0)
    {
        document.getElementById("AddFile").innerHTML = "Add a photo";
    }
}

function CheckFileType(file)
{
    $AllowExt = new Array('zip', 'rar', 'pdf', 'html', 'htm', 'jpg', 'bmp', 'doc', 'gif', 'png', 'jpeg', 'txt', 'csv');
    $AllowExt = $AllowExt.sort();
    re = /[^\.]+$/;
    ext = re.exec(document.getElementById("file"+file).value) + "";
    ext = ext.toLowerCase();
    $msg = "Only the following file extensions are supported:\n";
    $allow = 0;
    while ($ae = $AllowExt.shift())
    {
        if ($ae == ext)
        {
            $allow = 1;
        }
        else
        {
            $msg += $ae + ", ";
        }
    }

    if ($allow == 0)
    {
        $msg = $msg.substring(0, $msg.length - 2);
        $msg += "\nIf you wish to attach this file, please compress it first using rar or zip.";
        alert($msg);
        RemoveUpload(file);
    }
}