# -*- coding: UTF-8 -*-

"""Scytale-N Codec - scytale content encoding.

This codec:

- en/decodes strings from str to str

- en/decodes strings from bytes to bytes

- decodes file content to str (read)

- encodes file content from str to bytes (write)

"""

from math import ceil

from ..__common__ import *

__examples__ = {

'enc(scytale0|scytale--10|scytale01)': None,

'enc(scytale2|scytale-2|scytale_2)': {'this is a test': "ti satshsi et"},

'enc(scytale5|scytale-5|scytale_5)': {'this is a test': "tithsei ssat "},

}

__guess__ = ["scytale-%d" % i for i in range(1, 10)]

PADDING_CHAR = ""

def scytale_encode(l):

def encode(text, errors="strict"):

s, n = "", int(ceil(len(text) / float(l)))

for x in range(l):

for y in range(n):

try:

s += text[y*l+x]

except IndexError:

s += PADDING_CHAR

return s, len(s)

return encode

def scytale_decode(l):

def decode(text, errors="strict"):

s, n = "", int(ceil(len(text) / float(l)))

pl = l * n - len(text)

for x in range(n):

for y in range(l):

if y >= l-pl and x == n-1:

continue

s += text[y*n+x-max(0,y-(l-pl))]

s = s.rstrip(PADDING_CHAR)

return s, len(s)

return decode

add("scytale", scytale_encode, scytale_decode, r"^scytale[-_]?([1-9]\d*)$")