import __main__
from os import urandom as _urandom
from hashlib import sha1 as _sha1
from base64 import encodebytes as _encodebytes, b64encode as _b64encode
from json import load as _load, dump as _dump
from os.path import dirname as _dirname, abspath as _abspath, join as _join, isfile as _isfile


_HERE = _dirname(_abspath(__main__.__file__))
_SSHA_PASSWORD_DIR = _join(_HERE, 'password', 'ssha.json')


# unproudly borrowed from
# http://www.openldap.org/faq/data/cache/347.html
def ssha_encode(password):
    # do not regenerate SSHA
    if _isfile(_SSHA_PASSWORD_DIR):
        with open(_SSHA_PASSWORD_DIR, 'r') as fh:
            passwords = _load(fh)
    else:
        passwords = {}
    if password in passwords:
        return passwords[password]
    salt = _urandom(4)
    h = _sha1(password.encode())
    h.update(salt)
    ret = _b64encode(b"{SSHA}" + _encodebytes(h.digest() + salt)[:-1]).decode()
    passwords[password] = ret
    with open(_SSHA_PASSWORD_DIR, 'w') as fh:
        _dump(passwords, fh)
    return ret