TAMU ENGR 102 login.py

import getpass


def login() -> None:
    username = input('username: ')
    password = getpass.getpass('password: ')
    if authenticate(username, password):
        print('ACCESS GRANTED')
    else:
        print('ACCESS DENIED')


def authenticate(username: str, password: str) -> bool:
    try:
        stored_password = get_password(username)
    except (FileNotFoundError, LookupError):
        return False
    return stored_password == password


def get_password(username: str) -> str:
    # if user exists, return user's stored password
    # else raise Exception (file not found or user does not exist)
    username = username.lower()
    passwd = open('passwd')
    for line in passwd:
        # trim the newline
        line = line[:-1]
        uname, pword = line.split(':')
        if username == uname:
            return pword
    raise LookupError('user does not exist')


if __name__ == '__main__':
    login()