#!/usr/bin/env python

import sys
import os.path
import zipfile
from lxml import etree
from random import randint
from binascii import hexlify as _hexlify

# source of random data
#randdev = '/dev/urandom'
randdev = '/dev/random'
#randdev = '/dev/hwrng'
#randdev = '/var/run/rtl_entropy.fifo'

# 3 digit book id
#id = '%03d' % randint(0, 999)

# 2 digit book id with 1 digit checksum
id = '%02d' % randint(0, 99)
id += str((10 - int(id[0]) - int(id[1])) % 10)

def chartodigit(char):
  seed = int(_hexlify(char), 16)
  max = str(256**len(char)-1)
  count = len(max)
  for i in range(1, count):
    div = int(max[:i].ljust(count, '0'))
    if seed < div:
      return str(seed).zfill(count-i)[-(count-i):]
  return ''

infile = 'otp-template.odt'
outfile = 'otp-in-' + id + '.odt'

if os.path.exists(outfile):
  print >> sys.stderr, outfile, 'already exists'
  sys.exit(1)

# get 4125 digits from 1713 bytes
rng = open(randdev, 'rb')
digits = ''
for i in range(6):
  digits += chartodigit(rng.read(267))
digits += chartodigit(rng.read(49))
digits += chartodigit(rng.read(49))
digits += chartodigit(rng.read(13))
while len(digits) < 4125:
  digits += chartodigit(rng.read(5))
rng.close
digits = digits[:4125]

# add spaces every 5 digits
n = 5
temp = ''
for i in range(0, len(digits), n):
  temp += digits[i:i+n] + ' '
digits = temp

# split into 275 digit blocks
n = 330	# 275 digits + 55 spaces
pages = [digits[i:i+n] for i in range(0, len(digits), n)]

# sort pages
pages.sort()

# print
#order = [6, 10, 14, 0, 3, 7, 11, 1, 4, 8, 12, 2, 5, 9, 13]
#for i in order:
#  print '\n','\n',pages[i]

# open zip files
template = zipfile.ZipFile(infile)
otp = zipfile.ZipFile(outfile, 'w', zipfile.ZIP_DEFLATED)

# parse template
content = etree.parse(template.open('content.xml'))

# replace text
text = content.xpath('//text:p', namespaces={'text': 'urn:oasis:names:tc:opendocument:xmlns:text:1.0'})
for e in text:
  if e.text != None:
    # replace pages
    if e.text[:4] == 'PAGE':
      e.text = pages[int(e.text[4:])]
  for c in e:
    # replace book number
    if c.tail == '??? ':
      c.tail = id + ' '

# save new book
for item in template.infolist():
  buffer = template.read(item.filename)
  if (item.filename != 'content.xml'):
    otp.writestr(item, buffer)
  else:
    otp.writestr('content.xml', etree.tostring(content, xml_declaration=True, encoding='UTF-8'))

# close files
template.close()
otp.close()