PHP Consecutive File Naming - php

Question

So I'm fairly new to PHP and have been working on a web app that allows users to submit designs which are then saved as images (using html2canvas.js) to the server. I have the app working at the moment but it saves over any previous image with the same file name.
What I would like it to do is save with a consecutive number at the end of the file name so that previous designs are not overwritten. Working code below - the idea with the if else statement is that it checks for an existing file, if there isnt one, creates it (this code works) but if there is an existing file ... I dont know..
<?php
session_start();
$customerName = $_SESSION["design_name"];
//Get the base-64 string from data
$filteredData=substr($_POST['img_val_server'], strpos($_POST['img_val_server'], ",")+1);
//Decode the string
$unencodedData=base64_decode($filteredData);
//Check for previous user images
$fileName = '/customer-submits/design-' . $customerName . '.png';
if (file_exists($filename)) {
//THIS IS WHERE IS WANT THE FILE TO SAVE CONSECUTIVELY
} else {
//Save the image
file_put_contents('customer-submits/design-' . $customerName . '.png', $unencodedData);
$file = 'customer-submits/design-' . $customerName . '.png' ;
$fileName = basename($file);
$fileSize = filesize($file);
set_time_limit(0);
header("Pragma: public");
header("Expires: 0"); // Cache Options
header("Cache-Control: must-revalidate, post-check=0, pre-check=0"); // Cache Options
header("Content-type: application/octet-stream");
header("Content-Disposition: filename=\" " . $fileName ."\"");
header("Content-length: " . $fileSize);
readfile($file);
include 'sendMail.php';
echo send_mail();
}
?>
Would obviously very much appreciate any help with this, as Im struggling to get my head around php!

Answer 1

This should add a new number to the end of the customers name if a similar customers name appears.
$num = 0;
while (file_exists($filename)==TRUE) {
$num++;
$file = 'customer-submits/design-' . $customerName $num . '.png' ;
}
I added ==TRUE into my previous code which makes it a Boolean and should take away the parsing error you got earlier.

Answer 2

Try this after "//Check for previous user images", replacing the if...else:
$indx = 1;
$filename = '/customer-submits/design-' . $customerName . $indx . '.png';
while (file_exists ($filename) {
$indx++;
$filename = '/customer-submits/design-' . $customerName . $indx . '.png';
}