JSPDF create a pdf and attach to email

Hello, I'm having trouble generating an email with an attachment. The attachment is a PDF file generated by the JSPDF library. First I started by generating the pdf and calling the php script through ajax.

var pdf = doc.output(); 
$.post(
    "/smt/mail.php", 
    { 
        data: pdf 
    }, 
    function(data) {
        console.log(data.resultado); 
    }
, 'json');

I also tried with the line of code var pdf = btoa(doc.output());

but the error seems to be the same In the PHP script I have:

$semi_rand = md5(time()); 
$mime_boundary = "==Multipart_Boundary_x{$semi_rand}x";    

// multipart boundary 
$message = "--{$mime_boundary}\n" . "Content-Type: text/html; charset=\"UTF-8\"\n" .
"Content-Transfer-Encoding: 7bit\n\n" . $message . "\n\n"; 

// preparing attachments
if(count($files) > 0){
    for($i=0;$i<count($files);$i++){
        if(is_file($files[$i])){

            $message .= "--{$mime_boundary}\n";
            $fp =    fopen($files[$i],"rb");
            $data =  fread($fp,filesize($files[$i]));
            fclose($fp);
            $data = chunk_split(base64_encode($data));
            $message .= "Content-Type: application/octet-stream; name=\"".basename($files[$i])."\"\n" . 
            "Content-Description: ".basename($files[$i])."\n" .
            "Content-Disposition: attachment;\n" . " filename=\"".basename($files[$i])."\"; size=".filesize($files[$i]).";\n" . 
            "Content-Transfer-Encoding: base64\n\n" . $data . "\n\n";
        }
    }
}
$message .= "--{$mime_boundary}--";


$mail = new PHPMailer(true);
try{
$mail->IsSMTP();
$mail->SMTPAuth   = true;                  // enable SMTP authentication
//$mail->SMTPDebug = 1;
$mail->CharSet = 'UTF-8';
//$mail->Host = 'smtp.office365.com';
$mail->Host = 'mail2.mailbox.pt';
$mail->Username   = "****"; // SMTP account username example
$mail->Password   = "****";        // SMTP account password example
$mail->SMTPSecure = 'tls';                            // Enable TLS encryption, 'ssl' also accepted
$mail->Port = 587;    
$mail->From = "***";
$mail->FromName = "******";
$mail->AddAddress($to, "Test"); 
$mail->AddReplyTo("****", '*****');
$mail->IsHTML(true);
$mail->Subject = $subject;
$mail->Body    =  $message;

$mail->Send())

With this code I can send the mail however without the attachment After a bit of debugging I made sure that the condition line if(is_file[$i]) returned false.

Can someone help me?

Thanks in advance