Trouble with php upload - php

Question

I am working on php upload and i have an issue on how to automatically rename a file it does exist already in file folder. Could you give me any road or tips about it? thanks
here is my full code - the code is for testing purpose only
$destination = 'C:/upload_test/';
$max=75200;
if (isset($_POST['upload'])) {
if (isset($_FILES['image']['tmp_name'])) {
$fileTaille= $_FILES['image']['size'];
if ($fileTaille==true) {
if ($fileTaille > $max) {
echo "Your file is too large, select a file smaller than". " ".$fileTaille;
exit(include 'form.php');
}
}
else {
echo "No file selected";
exit(include 'form.php');
}
}
$file_type=getimagesize($_FILES['image']['tmp_name']);
if ($file_type==true) {
echo "File is an image - " .$file_type["mime"]." ";
}
else{
echo "Could not get file type";
}
$fileType = exif_imagetype($_FILES['image']['tmp_name']);
$allowed = array(IMAGETYPE_JPEG, IMAGETYPE_PNG, IMAGETYPE_GIF);
if (!in_array($fileType, $allowed)) {
echo "File type not accepted, Only JPEG file allowed";
exit(include 'form.php');
}
$sanitize_file = preg_replace("/[^A-Z0-9\.\_-]/i", " ", $_FILES["image"]["name"]);
$fileName = $recipient . basename($recipient);
if (file_exists($fileName)) {
echo "File already exist";
exit(include 'form.php');
}
}
if (isset($_FILES['image']['tmp_name'])) {
$result = move_uploaded_file($_FILES['image']['tmp_name'], $recipient . $sanitize_file);
if ($result == true) {
echo "file moved "." ";
}else
{
echo "Could not move filed";
}
$permission = chmod($$recipient . $sanitize_file, 0644);
if ($permission==false) {
echo "No permission to the file";
}
else
{
echo "permission given";
}
}