#!/usr/bin/env python
# -*- coding: utf-8; -*-
"""
* Copyright 2014 Alexandre Possebom
* Copyright 2014 Red Dye No. 2
* Copyright (C) 2011-2013 TG Byte Software GmbH
* Copyright (C) 2009-2011 Thilo-Alexander Ginkel.
* Copyright (C) 2010-2014 Eric Woodruff
* Copyright (C) 2006-2010 Steve Cooper

This file is part of twik.

Twik is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Twik is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Twik.  If not, see <http://www.gnu.org/licenses/>.
"""

import argparse
import base64
import getpass
import hmac
import sys
from hashlib import sha1

from .util import Util


class Twik(object):
	def injectcharacter(self, mhash, offset, reserved, seed, length, cstart, cnum):
		pos0 = seed % length
		pos = (pos0 + offset) % length
		for i in range(0, length - reserved):
			tmp = (pos0 + reserved + i) % length
			char = ord(mhash[tmp])
			if char >= ord(cstart) and char < ord(cstart) + cnum:
				return mhash
		head = mhash[:pos] if pos > 0 else ''
		inject = ((seed + ord(mhash[pos])) % cnum) + ord(cstart)
		tail = mhash[pos+1:] if (pos + 1 < len(mhash)) else mhash
		return head + chr(inject) + tail


	def removespecialcharacters(self, mhash, seed, length):
		inputchars = list(mhash)
		pivot = 0
		for i in range(0, length):
			if not inputchars[i].isdigit() and not inputchars[i].isalpha():
				inputchars[i] = chr(((seed + pivot) % 26 + ord('A')))
				pivot = i + 1
		return ''.join(inputchars)

	def converttodigits(self, mhash, seed, length):
		inputchars = list(mhash)
		pivot = 0
		for i in range(0, length):
			if not inputchars[i].isdigit():
				inputchars[i] = chr(((seed + ord(inputchars[pivot])) % 10 +
					ord('0')))
				pivot = i + 1
		return ''.join(inputchars)

	def generatehash(self, tag, key, length, password_type):
		digest = hmac.new(str.encode(key), str.encode(tag), sha1).digest()
		mhash = base64.b64encode(digest)[:-1]
		mhash = mhash.decode('utf-8')
		seed = sum([ord(i) for i in mhash])

		# NUMERIC
		if password_type == 3:
			mhash = self.converttodigits(mhash, seed, length)
		else:
			mhash = self.injectcharacter(mhash, 0, 4, seed, length, '0', 10)
			# ALPHANUMERIC_AND_SPECIAL_CHARS
			if password_type == 1:
				mhash = self.injectcharacter(mhash, 1, 4, seed, length, '!', 15)
			mhash = self.injectcharacter(mhash, 2, 4, seed, length, 'A', 26)
			mhash = self.injectcharacter(mhash, 3, 4, seed, length, 'a', 26)

			# ALPHANUMERIC
			if password_type == 2:
				mhash = self.removespecialcharacters(mhash, seed, length)

		return mhash[:length]


	def getpassword(self, tag, private_key, master_key, length, password_type):
		if length > 26 or length < 4:
			return None
		mhash = self.generatehash(private_key, tag, 24, 1)
		password = self.generatehash(mhash, master_key, length, password_type)
		return password

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