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

"""Base122 Codec - base122 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 ._base import main

from ..__common__ import *

__examples__ = {

'enc(base122|base-122)': {

'this is a test': ":\x1aʗ\x19\x01Rs\x10\x18$\x07#\x15ft",

b'This is another longer test string with d1g1t5 and sp3c141 characters !\n': \

b"*\x1a\xca\x97\x19\x01Rs\x10\x18-f{QPe9\x08\xcb\x86{9Ne9\x08\x0eF+Mh 9]\x0e\xd3\x8b"

b"9N ;Z.FA\x01H13L.C)\x01Bn2\x08\x0e7\x01MF1\x1a\x0c$\x06\x1b!Br0XnF+If \x10B@"

},

'enc-dec(base_122)': ["@random"],

}

_BAD = [0, 10, 13, 34, 38, 92]

_i = lambda c: c if isinstance(c, int) else ord(c)

# inspired from: https://github.com/kevinAlbs/Base122/blob/master/base122.js

def base122_encode(input, errors="strict"):

idx, bit, r, l = 0, 0, [], len(input)

def _get_7bits(idx, bit):

if idx >= l:

return idx, bit, False

B1 = _i(input[idx])

p1 = (((254 >> bit) & B1) << bit) >> 1

bit += 7

if bit < 8:

return idx, bit, p1

bit -= 8

idx += 1

if idx >= l:

return idx, bit, p1

B2 = _i(input[idx])

p2 = (((65280 >> bit) & B2) & 255) >> (8 - bit)

return idx, bit, (p1 | p2)

while True:

if idx >= l:

break

# get seven bits of input data

idx, bit, B = _get_7bits(idx, bit)

# check for illegal chars

try:

bad_idx = _BAD.index(B)

except ValueError:

r.append(B)

continue

idx, bit, nB = _get_7bits(idx, bit)

if nB is False:

nB, bad_idx = B, 7

B1, B2 = 194, 128

B1 |= (7 & bad_idx) << 2

B1 |= int((nB & 64) > 0)

B2 |= nB & 63

r.extend([B1, B2])

return "".join(map(chr, r)).encode("latin-1"), len(input)

# inspired from: https://github.com/kevinAlbs/Base122/blob/master/base122.js

def base122_decode(input, errors="strict"):

currB, bob, r, input = 0, 0, [], list(map(ord, input))

def _get_7bits(currB, bob, B, decoded):

B <<= 1

currB |= (B % 0x100000000) >> bob

bob += 7

if bob >= 8:

decoded += [currB]

bob -= 8

return (B << (7 - bob)) & 255, bob

for i in range(len(input)):

if input[i] >= 128:

try:

currB, bob = _get_7bits(currB, bob, _BAD[(input[i] >> 8) & 7], r)

except IndexError:

pass

currB, bob = _get_7bits(currB, bob, input[i] & 127, r)

else:

currB, bob = _get_7bits(currB, bob, input[i], r)

return "".join(map(chr, r)).rstrip("\0"), len(input)

add("base122", base122_encode, base122_decode, r"^base[-_]?122$", expansion_factor=1.085)

main122 = main(122, "<http://blog.kevinalbs.com/base122>", wrap=False)