Monitoring Folders - Python

Question

I am trying to write a python script which will monitor folders. The files are being written into the folder from a third party GUI based program. Some exported files grow in situ and other are written in a tmp folder elsewhere before being copied into the target folder. In the tmp folder cases, an empty folder is placed at the target destination until the file is ready to move. There may be multiples of these empty folders, but they are only created after the previous one has been populated.

The below appears to work well until there are Zero size files/folders.

I think the main issue lies in zero_files. Providing the rest for context.

import os
import datetime
import time
import itertools

print('Starting to Monitor File growth')
print(datetime.datetime.now())
print("")

path = os.path.normpath(r'C:\Users\ed\Desktop\Test_Run')
check_rate = 180
#time in seconds between checks

print("Waiting for a moment before starting monitoring")
print("")

time.sleep(60)
#wait for the first files to appear

def get_directory_size(directory):
    """Returns the `directory` size in bytes."""
    total = 0
    try:
        # print("[+] Getting the size of", directory)
        for entry in os.scandir(directory):
            if entry.is_file():
                # if it's a file, use stat() function
                total += entry.stat().st_size
            elif entry.is_dir():
                # if it's a directory, recursively call this function
                try:
                    total += get_directory_size(entry.path)
                except FileNotFoundError:
                    pass
    except NotADirectoryError:
        # if `directory` isn't a directory, get the file size then
        return os.path.getsize(directory)
    except PermissionError:
        # if for whatever reason we can't open the folder, return 0
        return 0
    return total

def folder_growing(path):
    sizes = [1,2]
    while sizes[-1] > sizes[-2]:
        time.sleep(check_rate)
        sizes.append(get_directory_size(path))
        print('Monitoring Folder')
    
def zero_files(path):
    files = os.listdir(path)
    a= []
    for i in files:
        file_size = a.append(os.path.getsize(f'{path}\\{i}'))
        a.sort()
    try:
        while a[-1] == 0:
            file_size = a.append(os.path.getsize(f'{path}\\{i}'))
            a.sort()
            print("test")
            time.sleep(120)
    except FileNotFoundError:
        pass

print(f"***Checking folders every", (int(check_rate/60)),"mins***")

get_directory_size(path)

folder_growing(path)

time.sleep(120)

zero_files(path)


wait = 10

print('No Folder Growth Detected')
print("")
print(f"***Waiting ", (int(wait/60)),"mins for Safety***")
time.sleep(wait)
print("")
print(datetime.datetime.now())
print("Done")