relative-to-absolute.py

import os
import re
from argparse import ArgumentParser

argument_parser = ArgumentParser()
argument_parser.add_argument('root')
argument_parser.add_argument('file')

args = argument_parser.parse_args()

args_root = os.path.abspath(args.root)
args_file = os.path.abspath(args.file)

module = args_root[args_root.rfind('/') + 1:]
module_path = args_file.replace(args_root, '')
module_path = module_path[1:module_path.rfind('/')]
module_path = module_path.replace('/', '.')
module_path = f'{module}.{module_path}'
module_parts = module_path.split('.')

regex = r'from (\.+)'

print(f'Processing {args_file}...')

with open(args_file, 'r') as file:
    content = file.read()

x = {}
matches = re.finditer(regex, content, re.MULTILINE)
for match_index, match in enumerate(matches, start=1):
    matched_string = match.group()
    x[matched_string] = None

x = sorted(x.keys(), key=lambda x: len(x), reverse=True)

for old in x:
    dot_count = old.count('.')

    replace = '.'.join(module_parts[:len(module_parts)-(dot_count-1)])

    new = f'from {replace}.'

    content = content.replace(old, new)

with open(args_file, 'w') as file:
    file.write(content)