#!/usr/bin/env python
"""
Generate a random password with controllable characteristics.
Mark Fickett [ naib.webhop.org ]
2008 Dec 15
"""

import string
import random
import optparse

def GeneratePassword(
	length=8,
	exclude='',
	lowercaseWeight=1.0,
	uppercaseWeight=1.0,
	digitWeight=1.0,
	punctuationWeight=1.0) :
	charInfo = [
		(lowercaseWeight,	string.lowercase),
		(uppercaseWeight,	string.uppercase),
		(digitWeight,		string.digits),
		(punctuationWeight,	string.punctuation),
	]
	choices = []
	excludeSet = set(exclude)
	totalWeight = 0
	for weight, charString in charInfo:
		charSet = set(charString)
		charSet -= excludeSet
		sectionWeight = max(0, weight)*len(charSet)
		if sectionWeight == 0:
			continue
		choices.append( (sectionWeight, list(charSet)) )
		totalWeight += sectionWeight

	password = ''
	if totalWeight == 0:
		return password

	for n in xrange(0, length):
		i = random.random()*totalWeight
		for wt, charList in choices:
			if i < wt:
				index = int((i/wt)*len(charList))
				password += charList[index]
				break
			else:
				i -= wt

	return password

def main():
	parser = optparse.OptionParser()
	parser.add_option("-n", "--numchars", dest="numchars", default=8,
		help="number of characters in the desired password")
	parser.add_option("-e", "--exclude", dest="exclude", default='',
		help="exclude characters found in EXCLUDESTRING",
		metavar="EXCLUDESTRING")
	parser.add_option("-l", "--lowercase-weight", dest="lower", default=1,
		help="relative weighting for characters in the lowercase set")
	parser.add_option("-u", "--uppercase-weight", dest="upper", default=1,
		help="relative weighting for characters in the uppercase set")
	parser.add_option("-d", "--digit-weight", dest="digit", default=1,
		help="relative weighting for characters in the digit set")
	parser.add_option("-p", "--punctuation-weight", dest="punct", default=1,
		help="relative weighting for characters in the punctuation set")
	options, args = parser.parse_args()

	print GeneratePassword(
		length =		int(options.numchars),
		exclude =		str(options.exclude),
		lowercaseWeight =	float(options.lower),
		uppercaseWeight =	float(options.upper),
		digitWeight =		float(options.digit),
		punctuationWeight =	float(options.punct))

if __name__ == "__main__":
	main()