# -*- coding: UTF-8 -*-
"""Citrix Codec - citrix password 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)

Reference: https://crypto.interactive-maths.com/atbash-cipher.html
"""
from ..__common__ import *


__examples__ = {
    'enc(citrix-ctx0)':                 None,
    'enc(citrix|citrix-1|citrix_ctx1)': {'this is a test': "NBBMNAAGIDEPJJBMNIFNIMEMJKEL"},
}
__guess__ = ["citrix-ctx1"]


_dec = lambda g: ((ord(g[0]) - 0x41) & 0xf) ^ ((((ord(g[1]) - 0x41) & 0xf) << 4) & 0xf0)
_enc = lambda o: chr(((o >> 4) & 0xf) + 0x41) + chr((o & 0xf) + 0x41)


def citrix_encode(t):
    def encode(text, errors="strict"):
        l = len(text)
        r, x = "", 0
        for c in text:
            x = ord(c) ^ 0xa5 ^ x
            r += _enc(x)
        return r, l
    return encode


def citrix_decode(t):
    def decode(text, errors="strict"):
        l = len(text)
        text = text[::-1]
        r = ""
        for i in range(0, l, 2):
            x = 0 if i + 2 >= l else _dec(text[i+2:i+4])
            x ^= _dec(text[i:i+2]) ^ 0xa5
            r += chr(x)
        return r[::-1], l
    return decode


add("citrix", citrix_encode, citrix_decode, r"citrix(|[-_]?(?:ctx)?1)$", entropy=4., printables_rate=1.,
    expansion_factor=2.)