#!/usr/bin/env python

"""
SYNOPSIS

    randpass [-h, --help] [--cap] [--nato]

DESCRIPTION

    This generates a random password that is easy to pronounce. The passwords
    are built up of pairs of Conssonants and Vowels. It helps to read the
    letters in pairs. These passwords are easy to pronounce and I found that I
    can remember them for a few minutes without trying very hard.

    This is not intended to create great passwords, but "good enough"
    passwords. Some misguided admins create passwords so complicated that 
    they guarantee that I will never remember them.

    The "apg" program uses an algorithm defined in FIPS PUB 181 which claims,
    "Approximately 18 million 6-character, 5.7 billion 8-character, and 1.6
    trillion 10-character passwords can be created by the program." The "pwgen"
    program simimlarly generates passwords. I don't find either of those
    password generators to create very pronouncable passwords. Most
    authentication systems limit login attempts, so I think these numbers are
    academic. The system in this script by default yields up to 61,412,500
    8-letter passwords -- which may not be a lot if you are using this for your
    recall codes, but at least it beats "poe". If the passwords are not long
    enough for your application then use the --num option to create a longer
    password. By default this script creates passwords made of three pairs of
    letters plus two digits (8 characters total).

EXAMPLES

    $ randpass
    mayomi22

    $ randpass --cap
    MoNuRi45

    $ randpass --nato
    wenogu36, "whiskey echo november oscar golf uniform three six"

    $ randpass --cap --nato
    HeSoTu95, "hotel echo sierra oscar tango uniform nine five"
    
    $ randpass --num=6
    hiwasitagumo67

AUTHOR

    Noah <noah@noah.org>

LICENSE

    This script is in the public domain, free from copyrights or restrictions.

VERSION

    $Id: randpass.py 144 2007-12-19 01:00:41Z root $
"""

import sys, os, traceback, optparse
import random

def nato (s):

    """This translates a string into NATO phonetics.
    """

    alpha = {'a':'alpha', 'b':'bravo', 'c':'charlie', 'd':'delta',
            'e':'echo', 'f':'foxtrot', 'g':'golf', 'h':'hotel', 'i':'india',
            'j':'juliet', 'k':'kilo', 'l':'lima', 'm':'mike', 'n':'november',
            'o':'oscar', 'p':'papa', 'q':'quebec', 'r':'romeo', 's':'sierra',
            't':'tango', 'u':'uniform', 'v':'victor', 'w':'whiskey',
            'y':'yankee', 'z':'zulu',
            '0':'zero', '1':'one', '2':'two', '3':'three', '4':'four',
            '5':'five', '6':'six', '7':'seven', '8':'eight', '9':'niner'}
    s = s.lower()
    n = ''
    n = [n+alpha[c] for c in s if c in alpha]
    n = ' '.join(n)
    return n

def main ():

    global options, args
    
    #C = ('th','ch','w','r','t','y','p','s','d','f','g','h','j','k','z','v','b','n','m')
    C = ('w','r','t','y','p','s','d','f','g','h','j','k','z','v','b','n','m')
    V = ('a','e','i','o','u')
    ph = [(c+v) for c in C for v in V]
    pc = len(ph)

    p = []
    for i in range(options.num):
        if options.cap:
            p.append (ph[random.randrange(pc)].capitalize())
        else:
            p.append (ph[random.randrange(pc)])
    n3 = random.choice('0123456789')
    n4 = random.choice('0123456789')
    if options.verbose:
        print "%d possible %d phoneme words" % (pow(pc,options.num),options.num)
        print "%d possible with a two digit random number" % (pow(pc,options.num)*100)
    pw = ''.join(p) + n3 + n4
    if options.nato:
        print pw + ', "' + nato(pw) + '"'
    else:
        print pw

if __name__ == '__main__':
    try:
        parser = optparse.OptionParser(formatter=optparse.TitledHelpFormatter(), usage=globals()['__doc__'], version='$Id: py.tpl 144 2007-12-19 01:00:41Z root $')
        parser.add_option ('-v', '--verbose', action='store_true', default=False, help='verbose output')
        parser.add_option ('-p', '--nato', action='store_true', default=False, help='NATO phonetic output')
        parser.add_option ('-c', '--cap', action='store_true', default=False, help='Capitalize each phoneme')
        parser.add_option ('-n', '--num', type='int', default=3, help='Number of phonemes')

        (options, args) = parser.parse_args()
        #if len(args) < 1:
        #    parser.error ('missing argument')
        main()
        sys.exit(0)
    except KeyboardInterrupt, e: # Ctrl-C
        raise e
    except SystemExit, e: # sys.exit()
        raise e
    except Exception, e:
        print 'ERROR, UNEXPECTED EXCEPTION'
        print str(e)
        traceback.print_exc()
        os._exit(1)