#! /usr/bin/env python3

import secrets
import argparse
import shutil

lower   = [chr(c) for c in range(ord('a'), ord('z') + 1)]
upper   = [chr(c) for c in range(ord('A'), ord('Z') + 1)]
number  = [chr(c) for c in range(ord('0'), ord('9') + 1)]
special = """!@#$%^&*()_+{}=-[];,.<>/?'""" + '"'

def parse_args():
  parser = argparse.ArgumentParser(description='Generate secure passwords with configurable character classes')

  parser.add_argument('-a', help='include lower case letters, default is yes', action='store_true')
  parser.add_argument('-A', help='include upper case letters, default is yes', action='store_true')
  parser.add_argument('-n', help='include numbers, default is yes', action='store_true')
  parser.add_argument('-s', help='include special characters, default is no', action='store_true')

  parser.add_argument('count', help='the number of password to generate, default is 5',
                      type=int, default=5, nargs='?')
  parser.add_argument('length', help='the length of the password being generated, default is 16',
                      type=int, default=16, nargs='?')

  return parser.parse_args()

def generate_characters(args):
  if (not args.a and not args.A and not args.n and not args.s):
    return "".join(lower) + "".join(upper) + "".join(number)

  chars = ""

  if args.a:
    chars += "".join(lower)

  if args.A:
    chars += "".join(upper)

  if args.n:
    chars += "".join(number)

  if args.s:
    chars += special

  return chars

def generate_pw(chars, length):
  return "".join([secrets.choice(chars) for i in range(length)])

def pretify(pws):
  columns = shutil.get_terminal_size((80,20)).columns

  n = int(columns / (len(pws[0]) + 1))

  rows = [' '.join(pws[i:i + n]) for i in range(0, len(pws), n)]

  return '\n'.join(rows)

def main():
  args = parse_args()

  chars = generate_characters(args)

  pws = [generate_pw(chars, args.length) for i in range(args.count)]

  print(pretify(pws))

if __name__ == '__main__':
  main()