#!/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
    that it can generate "Approximately 18 million 6-character, 5.7 billion
    8-character, and 1.6 trillion 10-character passwords." The "pwgen" program
    simimlarly generates passwords. I don't find either of those password
    generators to create very pronouncable or memorable 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
    character passwords -- which may not be a lot if you are using this for
    your bomber recall code, 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).

    The formula to give the search-space size of an arbitrary length password
    from an arbitrary length alphabet is as follows:
        sum([ALPHABET_LENGTH**nn for nn in range(PW_LENGTH+1)])
    So for an 8 character password using only lower-case letters, the
    search-space size is 217180147159 characters. The argorithm in this
    password generator does not easily fit this formula.

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 Spurrier <noah@noah.org>

LICENSE

    This license is approved by the OSI and FSF as GPL-compatible.
        http://opensource.org/licenses/isc-license.txt

    Copyright (c) 2012, Noah Spurrier
    PERMISSION TO USE, COPY, MODIFY, AND/OR DISTRIBUTE THIS SOFTWARE FOR ANY
    PURPOSE WITH OR WITHOUT FEE IS HEREBY GRANTED, PROVIDED THAT THE ABOVE
    COPYRIGHT NOTICE AND THIS PERMISSION NOTICE APPEAR IN ALL COPIES.
    THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
    MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

VERSION

    1
"""

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='1')
        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)