PHP - Watermarking Pdf Files Before Download Or View

$uploadDir = '../uploads/';

if(isset($_POST['upload']))
{
foreach ($_FILES as $file)
{
$fileName = $file['name'];
$tmpName = $file['tmp_name'];
$fileSize = $file['size'];
$fileType = $file['type'];

if($fileName==""){

$filePath = '../img/none.jpg';
}
else{

$filePath = $uploadDir . $fileName;
}

////generate random name
//// get the file extension first
$ext = substr(strrchr($fileName, "."), 1); 
//
//// make the random file name
$randName = md5(rand() * time());
//
//// and now we have the unique file name for the upload file
$filePath = $uploadDir . $randName . '.' . $ext;
// Replace spaces with a '_'
$filePath = str_replace(" ", "_", $filePath);
$result = move_uploaded_file($tmpName, $filePath);

//if (!$result) {
//echo "Error uploading file";
//exit;
//}


if(!get_magic_quotes_gpc())
{
$fileName = addslashes($fileName);
$filePath = addslashes($filePath);
}
$fileinsert[]=$filePath;
}
/*
 * PHP GD
 * adding watermark to an image with GD library
 */

// Load the watermark and the photo to apply the watermark to
$stamp = imagecreatefrompng('../img/watermark_fotos.png');
$im = imagecreatefromjpeg('$filePath');

// Set the margins for the stamp and get the height/width of the stamp image
$marge_right = 10;
$marge_bottom = 10;
$sx = imagesx($stamp);
$sy = imagesy($stamp);

// Copy the stamp image onto our photo using the margin offsets and the photo 
// width to calculate positioning of the stamp. 
imagecopy($im, $stamp, imagesx($im) - $sx - $marge_right, imagesy($im) - $sy - $marge_bottom, 0, 0, imagesx($stamp), imagesy($stamp));

// Output and free memory
header('Content-type: image/png');
imagepng($im);
imagedestroy($im);

Basically I would like to place a link on my website and have the user download a file, but rather than just right clicking and choosing save target as, the link must be clicked, on the next page the file is fetched and then the client can download the file. How would I go about setting this up please?

When the download appears the link that is produced doesn't show the actual download either, so users can't leech of it.

Thanks

I have made a Php program that downloads an Inno setup installation file for installing a program. However, if I for one or another reason want to make a new download of the same Inno setup installation file, the previous file will still be found in the Download folder. Each of the downloads get a number in parenthesis, setup(1), setup(2), setup(3) etc. However, I wondered if it is posible to erase the previous file in the same process as I download a new one, so that however many downloads I do, there will all the time only be one occurence of this file in the Download folder.

The download code is as follows:

$exe = "Inno script/Test_setup.exe";
	header("Content-Type: application/octet-stream"); 
	header("Content-Disposition: attachment; filename=\"Test_setup.exe\""); 
	header("Content-Length: " . filesize($exe)); 
	readfile($exe); 

Thanks in advance.

Sincerely

array:
[SomePath/test.php] = "All In this php file is being read by a new smart function!";
[SomePath/Weird/hello.txt = "Hello world. This is me and im just trying to get some help!";

So far I have managed to create an upload process which uploads a picture, updates the database on file location and then tries to upload the db a 2nd time to update the Thumbnails file location (i tried updating the thumbnails location in one go and for some reason this causes failure)

But the main problem is that it doesn't upload some files

Here is my upload.php

<?php
include 'dbconnect.php';

$statusMsg = '';

$Title = $conn -> real_escape_string($_POST['Title']) ; 
$BodyText = $conn -> real_escape_string($_POST['ThreadBody']) ; 
	 

// File upload path
$targetDir = "upload/";
$fileName = basename($_FILES["file"]["name"]);
$targetFilePath = $targetDir . $fileName;
$fileType = pathinfo($targetFilePath,PATHINFO_EXTENSION);
$Thumbnail = "upload/Thumbnails/'$fileName'";

if(isset($_POST["submit"]) && !empty($_FILES["file"]["name"])){
    // Allow certain file formats
    $allowTypes = array('jpg','png','jpeg','gif','pdf', "webm", "mp4");
    if(in_array($fileType, $allowTypes)){

        // Upload file to server
        if(move_uploaded_file($_FILES["file"]["tmp_name"], $targetFilePath)){

            // Insert image file name into database
            $insert = $conn->query("INSERT into Threads (Title, ThreadBody, filename) VALUES ('$Title', '$BodyText', '$fileName')");
            if($insert){
               $statusMsg = "The file ".$fileName. " has been uploaded successfully."; 

		$targetFilePathArg = escapeshellarg($targetFilePath);
		$output=null;
		$retval=null;
		 //exec("convert $targetFilePathArg -resize 300x200 ./upload/Thumbnails/'$fileName'", $output, $retval);
		 exec("convert $targetFilePathArg -resize 200x200 $Thumbnail", $output, $retval);
		echo "REturned with status $retval and output:\n" ; 
		if ($retval == null) { 
		echo "Retval is null\n" ;
		echo "Thumbnail equals $Thumbnail\n" ; 
		}

            }else{
                $statusMsg = "File upload failed, please try again.";
            } 
        }else{
            $statusMsg = "Sorry, there was an error uploading your file.";
        }
    }else{
        $statusMsg = 'Sorry, only JPG, JPEG, PNG, GIF, mp4, webm & PDF files are allowed to upload.';
    }
}else{
    $statusMsg = 'Please select a file to upload.';
}

//Update SQL db by setting the thumbnail column to equal $Thumbnail
$update = $conn->query("update Threads set thumbnail = '$Thumbnail' where filename = '$fileName'");
            if($update){
               $statusMsg = "Updated the thumbnail to sql correctly.";
		echo $statusMsg ;  } 
else 
{ echo "\n Failed to update Thumbnail. Thumbnail equals $Thumbnail" ; } 


// Display status message
echo $statusMsg;
?>

And this does work on most files however it is not working on a 9.9mb png file  which is named "test.png" I tested on another 3.3 mb gif file and that failed too?

For some reason it returns the following

Updated the thumbnail to sql correctly.Updated the thumbnail to sql correctly.

Whereas on the files it works on it returns

REturned with status 0 and output: Retval is null Thumbnail equals upload/Thumbnails/'rainbow-trh-stache.gif' Failed to update Thumbnail. Thumbnail equals upload/Thumbnails/'rainbow-trh-stache.gif'The file rainbow-trh-stache.gif has been uploaded successfully.

Any idea on why this is?