TAMU ENGR 102 add_user.py

import sys
import getpass
from login import get_password


def add_user(username: str = None, password: str = None) -> None:
    """
    Add a user to the password file.

    username -- the username (default None, will prompt user)
    password -- the password (default None, will prompt user)
    """

    if not username:
        username = input('username: ')
    if len(username) == 0:
            print('[FATAL] username cannot be empty. exiting...')
            return

    # enforce case insensitivity for username
    username = username.lower()

    if not validate_username(username):
        print('[FATAL] username contains illegal characters.  exiting...')
        return

    try:
        _passwd = get_password(username)
        print('[FATAL] user "{username:s}" already exists. exiting...'.format(username=username))
        return
    except (FileNotFoundError, LookupError):
        # FileNotFoundError: password file doesn't exist, will be created
        # LookupError: username does not exist, will be created
        pass

    if not password:
        password1 = getpass.getpass('password: ')
        password2 = getpass.getpass('confirm password: ')
        if not password1 == password2:
            print('[FATAL] passwords do not match. exiting...')
            return
        password = password1
    if len(password) == 0:
            print('[FATAL] password cannot be empty. exiting...')
            return

    with open('passwd', 'at') as passwd:
        passwd.write('{username:s}:{password:s}\n'.format(\
        username=username, password=password))


def validate_username(username: str) -> bool:
    for c in username:
        if c not in '_abcdefghijklmnopqrstuvwxyz0123456789':
            return False
    return True


if __name__ == '__main__':
    argc = len (sys.argv)
    uname = sys.argv[1] if argc > 1 else None
    pword = sys.argv[2] if argc > 2 else None
    add_user(uname, pword)