#!/usr/local/bin/python3
# -*- coding: utf-8 -*-
#
# @(#)$Id: //Administration/Server/Konfiguration/Dateien/_main/fmgbackup4/root/bin/genpwd.py#1 $
# $Change: 28588 $ $DateTime: 2018/10/31 13:11:48 $ $Author: fag $
#
r"""Generate passwords.

Usage: genpwd.py [ Options ] required_length

Options:

  --type, -t    web, web-safe, web-safe2, base64, base32, ascii85

:Author:  Franz Glasner

"""

from __future__ import (division, absolute_import, print_function)

__author__ = "Franz Glasner"

__version__ = "0.1"


import getopt
import sys
import os
import base64


WEB_CHARS = b"ABCDEFGHIJKLMNOPQRSTUVWYXZabcdefghijklmnopqrstuvwxyz0123456789.,-_;!()[]{}*"
WEB_SAFE_CHARS = b"ABCDEFGHJKLMNPQRSTUVWYXZabcdefghijkmnopqrstuvwxyz23456789.,-_;!"
WEB_SAFE2_CHARS = b".,-_;!" + WEB_SAFE_CHARS

PY2 = sys.version_info[0] <= 2


def main():
    opt_type = "web-safe2"
    opts, args = getopt.getopt(sys.argv[1:],
                               "t:",
                               ["type="])
    for opt, val in opts:
        if opt in ("-t", "--type"):
            if val not in ("web", "web-safe", "web-safe2",
                           "base64", "base32", "ascii85", ):
                raise getopt.GetoptError("invalid type: %s" % val, "")
            opt_type = val
        else:
            raise RuntimeError("inconsistent getopt handling")

    try:
        req_length = int(args[0], 10)
    except IndexError:
        raise getopt.GetoptError("no length given")

    if opt_type == "web":
        pwd = gen_web(req_length, WEB_CHARS)
    elif opt_type == "web-safe":
        pwd = gen_web(req_length, WEB_SAFE_CHARS)
    elif opt_type == "web-safe2":
        pwd = gen_web(req_length, WEB_SAFE2_CHARS)
    elif opt_type == "base64":
        encoder = base64.b64encode
        pwd = gen_bin(req_length, encoder)
    elif opt_type == "base32":
        encoder = base64.b32encode
        pwd = gen_bin(req_length, encoder)
    elif opt_type == "ascii85":
        encoder = base64.a85encode
        pwd = gen_bin(req_length, encoder)
    else:
        raise NotImplementedError("type not yet implemented: %s" % opt_type)
    print(pwd)


def gen_web(length, chars):
    mult = 256//len(chars)
    repertoire = chars * mult
    assert len(repertoire) <= 256
    pwd = []
    while len(pwd) < length:
        c = os.urandom(1)
        if PY2:
            c = ord(c)
        else:
            c = c[0]
        if c < len(repertoire):
            pwd.append(repertoire[c])
    if PY2:
        pwd = b''.join(pwd)
    else:
        pwd = bytes(pwd)
    return pwd


def gen_bin(length, encoder):
    pwd = encoder(os.urandom(length))
    return pwd[:length]


if __name__ == "__main__":
    main()