#!/usr/bin/env python3

import argparse
import os
import re


def _main():
    example_dir = os.path.dirname(__file__)

    args = _parse_args()

    renames = []

    for name in sorted(os.listdir(example_dir)):
        path = os.path.join(example_dir, name)
        match = re.match("([0-9]+)(-.*)", name)

        if os.path.isdir(path) and match is not None:
            old_number = int(match[1])
            is_in_range = (
                (args.from_number is None or args.from_number <= old_number) and
                (args.to_number is None or old_number <= args.to_number)
            )
            if is_in_range:
                new_number = old_number + args.delta
                new_name = f"{new_number:02}{match[2]}"
                new_path = os.path.join(example_dir, new_name)
                print(f"{name} -> {new_name}")

                if os.path.exists(new_path):
                    raise ValueError("destination already exists")

                renames.append((path, new_path))

    for old_path, new_path in renames:
        os.rename(old_path, new_path)


def _parse_args():
    parser = argparse.ArgumentParser()

    parser.add_argument("--delta", required=True, type=int)
    parser.add_argument("--from", required=False, type=int, dest="from_number")
    parser.add_argument("--to", required=False, type=int, dest="to_number")

    return parser.parse_args()


if __name__ == "__main__":
    _main()