Submit form with attachment to email - php

Question

My code here is:
<form action="#" method="POST" enctype="multipart/form-data" >
<input type="file" name="csv_file[]" />
<br/>
<input type="file" name="csv_file[]" />
<br/>
<input type="file" name="csv_file[]" />
<br/>
<input type="submit" name="upload" value="Upload" />
<br/>
</form>
<?php
if($_POST) {
for($i=0; $i < count($_FILES['csv_file']['name']); $i++){
$ftype[] = $_FILES['csv_file']['type'][$i];
$fname[] = $_FILES['csv_file']['name'][$i];
}
// array with filenames to be sent as attachment
$files = $fname;
// email fields: to, from, subject, and so on
$to = "example#gmail.com";
$from = "example#gmail.com";
$subject ="My subject";
$message = "My message";
$headers = "From: $from";
// boundary
$semi_rand = md5(time());
$mime_boundary = "==Multipart_Boundary_x{$semi_rand}x";
// headers for attachment
$headers .= "\nMIME-Version: 1.0\n" . "Content-Type: multipart/mixed;\n" . " boundary=\"{$mime_boundary}\"";
// multipart boundary
$message = "This is a multi-part message in MIME format.\n\n" . "--{$mime_boundary}\n" . "Content-Type: text/plain; charset=\"iso-8859-1\"\n" . "Content-Transfer-Encoding: 7bit\n\n" . $message . "\n\n";
$message .= "--{$mime_boundary}\n";
// preparing attachments
for($x=0;$x<count($files);$x++){
$file = fopen($files[$x],"rb");
$data = fread($file,filesize($files[$x]));
fclose($file);
$data = chunk_split(base64_encode($data));
$message .= "Content-Type: {\"application/octet-stream\"};\n" . " name=\"$files[$x]\"\n" .
"Content-Disposition: attachment;\n" . " filename=\"$files[$x]\"\n" .
"Content-Transfer-Encoding: base64\n\n" . $data . "\n\n";
$message .= "--{$mime_boundary}\n";
}
// send
$ok = #mail($to, $subject, $message, $headers);
if ($ok) {
echo "<p>mail sent to $to!</p>";
} else {
echo "<p>mail could not be sent!</p>";
}
}
?>
I got the code from here: https://stackoverflow.com/a/27565430/4357238
the form successfully sends the email and when i get the email, the name of the file(s) show up but the file is an empty file (0 bytes).
For example, i send a file called car.jpg and when it gets to my email, it shows up on my email as car.jpg but when i download the file and open the file, it says the file is broken and it cannot be opened because the file is empty.
what is wrong and how can i fix it?