MacOS – How to create a script with Automator to watermark each PDF in a folder with a different watermark

I am trying to create a script to watermark a group a PDF files in a folder, each PDF has to have a unique watermark.

All the PDFs are in one folder, all the watermarks are in .png located in another folder.
I currently have watermark script which I found on Apple Forums, but this was made to watermark all files with one watermark only.

What I need is a way to watermark each PDF file with it's own different watermark (there are 400 pdfs and 400 different watermarks)

Here is the contents of the watermark tool.py:

#!/usr/bin/python
# Watermark each page in a PDF document

import sys #, os
import getopt
import math
from Quartz.CoreGraphics import *
from Quartz.ImageIO import *

def drawWatermark(ctx, image, xOffset, yOffset, angle, scale, opacity):
    if image:
        imageWidth = CGImageGetWidth(image)
        imageHeight = CGImageGetHeight(image)
        imageBox = CGRectMake(0, 0, imageWidth, imageHeight)
        
        CGContextSaveGState(ctx)
        CGContextSetAlpha(ctx, opacity)
        CGContextTranslateCTM(ctx, xOffset, yOffset)
        CGContextScaleCTM(ctx, scale, scale)
        CGContextTranslateCTM(ctx, imageWidth / 2, imageHeight / 2)
        CGContextRotateCTM(ctx, angle * math.pi / 180)
        CGContextTranslateCTM(ctx, -imageWidth / 2, -imageHeight / 2)
        CGContextDrawImage(ctx, imageBox, image)
        CGContextRestoreGState(ctx)

def createImage(imagePath):
    image = None
    
    # provider = CGDataProviderCreateWithFilename(imagePath)    # FIXED: replaced by the following CGDataProviderCreateWithURL()
    url = CFURLCreateFromFileSystemRepresentation(kCFAllocatorDefault, imagePath, len(imagePath), False)
    provider = CGDataProviderCreateWithURL(url)
    
    if provider:
        imageSrc = CGImageSourceCreateWithDataProvider(provider, None)
        if imageSrc:
            image = CGImageSourceCreateImageAtIndex(imageSrc, 0, None)
    if not image:
        print "Cannot import the image from file %s" % imagePath
    return image

def watermark(inputFile, watermarkFiles, outputFile, under, xOffset, yOffset, angle, scale, opacity, verbose):
    
    images = map(createImage, watermarkFiles)
    
    ctx = CGPDFContextCreateWithURL(CFURLCreateFromFileSystemRepresentation(kCFAllocatorDefault, outputFile, len(outputFile), False), None, None)
    if ctx:
        pdf = CGPDFDocumentCreateWithURL(CFURLCreateFromFileSystemRepresentation(kCFAllocatorDefault, inputFile, len(inputFile), False))
        if pdf:
            
            for i in range(1, CGPDFDocumentGetNumberOfPages(pdf) + 1):
                image = images[i % len(images) - 1]
                page = CGPDFDocumentGetPage(pdf, i)
                if page:
                    mediaBox = CGPDFPageGetBoxRect(page, kCGPDFMediaBox)
                    if CGRectIsEmpty(mediaBox):
                        mediaBox = None
                    
                    CGContextBeginPage(ctx, mediaBox)
                    if under:
                        drawWatermark(ctx, image, xOffset, yOffset, angle, scale, opacity)
                    CGContextDrawPDFPage(ctx, page)
                    if not under:
                        drawWatermark(ctx, image, xOffset, yOffset, angle, scale, opacity)
                    CGContextEndPage(ctx)
    
        del pdf
        CGPDFContextClose(ctx)
    del ctx

def main(argv):
    
    verbose = False
    readFilename = None
    writeFilename = None
    under = False
    xOffset = 0.0   # FIXED: changed to float value
    yOffset = 0.0   # FIXED: changed to float value
    angle = 0.0     # FIXED: changed to float value
    scale = 1.0     # FIXED: added
    opacity = 1.0
    
    # Parse the command line options
    try:
        options, args = getopt.getopt(argv, "vutx:y:a:p:s:i:o:", ["verbose", "under", "over", "xOffset=", "yOffset=", "angle=", "opacity=", "scale=", "input=", "output=", ])
    except getopt.GetoptError:
        usage()
        sys.exit(2)

    for option, arg in options:
        
        print option, arg
        
        if option in ("-i", "--input") :
            if verbose:
                print "Reading pages from %s." % (arg)
            readFilename = arg
        
        elif option in ("-o", "--output") :
            if verbose:
                print "Setting %s as the output." % (arg)
            writeFilename = arg
        
        elif option in ("-v", "--verbose") :
            print "Verbose mode enabled."
            verbose = True
        
        elif option in ("-u", "--under"):
            print "watermark under PDF"
            under = True
        
        elif option in ("-t", "--over"):    # FIXED: changed to "-t" from "t"
            print "watermark over PDF"
            under = False
        
        elif option in ("-x", "--xOffset"):
            xOffset = float(arg)
        
        elif option in ("-y", "--yOffset"):
            yOffset = float(arg)
        
        elif option in ("-a", "--angle"):
            angle = -float(arg)
        
        elif option in ("-s", "--scale"):
            scale = float(arg)
        
        elif option in ("-p", "--opacity"):
            opacity = float(arg)
        
        else:
            print "Unknown argument: %s" % (option)

    if (len(args) > 0):
        watermark(readFilename, args, writeFilename, under, xOffset, yOffset, angle, scale, opacity, verbose);
    else:
        shutil.copyfile(readFilename, writeFilename);

def usage():
    print "Usage: watermark --input <file> --output <file> <watermark files>..."

if __name__ == "__main__":
    print sys.argv
    main(sys.argv[1:])