Upload File PHP

Html

<form action="uploadit.php" enctype="multipart/form-data" method="post">
<input name="action" type="hidden" value="upload" />
Upload image:
<input name="photo" type="file" /><br />
<input type="submit" value="upload" />
</form>

PHP

 
<?

if ($_FILES['photo']['size'] > 524288){ //Maximal File upload 500kb
echo "Over type";
}

elseif ($_FILES['photo']['type'] != "image/jpeg" AND $_FILES['photo']['type'] != "image/pjpeg" AND $_FILES['photo']['type'] != "image/png" AND $_FILES['photo']['type'] != "image/gif"){
echo "gagal";
    }

elseif ($_FILES['photo']['name'] != ''){
        $sUploadDir = 'upload/';
        $nama=rand(0000,9999);
        $random_digit=sha1($nama);
        $sUploadedFile = $sUploadDir . basename($_FILES['photo']['name']);
   if (move_uploaded_file($_FILES['photo']['tmp_name'], $sUploadedFile)) {
        $sThumbnail = $_FILES['photo']['name'];
        $sThumbnail = $random_digit."_".$sThumbnail;//File simpan
        $sFileName = strtolower(($sThumbnail));
        if (file_exists(($sUploadDir.$_FILES['photo']['name'])))
        rename(($sUploadDir.$_FILES['photo']['name']), ($sUploadDir.$sFileName));
       
echo "file uploaded successfully";
    }
}
else{

echo "uploaded";
}

?>