Script to set download path

set_download_path.py

import os
import sys
from pathlib import Path
from typing import List, Optional

def _exit(message: str, status=0):
    'Gracefully exit with status code and message to stderr.'
    if status != 0:
        sys.stderr.write(message)
    raise SystemExit(status)


def set_download_path(path: Optional[str] = None) -> Path:
    '''
    Perform several sanity checks against given path (in string), exit if at least one check are not passed.
    Return PurePath object from given path, if path is None return PurePath object from current working directory.
    '''
    if not path:
        dest_dir = Path.cwd().resolve()
    else:
        _path = Path(path)
        message = ('Given path is not {reason}.\n'
                    'Please specify different path or not specify path at all '
                    'to download to current directory.')
        if not Path.exists(_path):
            _exit(message.format(reason = 'exist'), 1)
        elif not Path.is_dir(_path):
            _exit(message.format(reason = 'a folder'), 1)
        elif not os.access(_path, os.W_OK):
            _exit(message.format(reason = 'writable'), 1)
        else:
            dest_dir = _path

    return dest_dir