module Codec.Binary.Base32Hex
( encode
, decode
, decode'
, chop
, unchop
) where
import Control.Monad
import Data.Array
import Data.Bits
import Data.Maybe
import Data.Word
import qualified Data.Map as M
import qualified Codec.Binary.Base32 as Base32
_encMap =
[ (0, '0'), (1, '1'), (2, '2'), (3, '3'), (4, '4')
, (5, '5'), (6, '6'), (7, '7'), (8, '8'), (9, '9')
, (10, 'A'), (11, 'B'), (12, 'C'), (13, 'D'), (14, 'E')
, (15, 'F'), (16, 'G'), (17, 'H'), (18, 'I'), (19, 'J')
, (20, 'K'), (21, 'L'), (22, 'M'), (23, 'N'), (24, 'O')
, (25, 'P'), (26, 'Q'), (27, 'R'), (28, 'S'), (29, 'T')
, (30, 'U'), (31, 'V') ]
encodeArray :: Array Word8 Char
encodeArray = array (0, 32) _encMap
decodeMap :: M.Map Char Word8
decodeMap = M.fromList [(snd i, fst i) | i <- _encMap]
encode :: [Word8]
-> String
encode = let
pad n = replicate n 0
enc [] = ""
enc l@[o] = (++ "======") . take 2 . enc $ l ++ pad 4
enc l@[o1, o2] = (++ "====") . take 4 . enc $ l ++ pad 3
enc l@[o1, o2, o3] = (++ "===") . take 5 . enc $ l ++ pad 2
enc l@[o1, o2, o3, o4] = (++ "=") . take 7 . enc $ l ++ pad 1
enc (o1 : o2 : o3 : o4 : o5 : os) = let
i1 = o1 `shiftR` 3
i2 = (o1 `shiftL` 2 .|. o2 `shiftR` 6) .&. 0x1f
i3 = o2 `shiftR` 1 .&. 0x1f
i4 = (o2 `shiftL` 4 .|. o3 `shiftR` 4) .&. 0x1f
i5 = (o3 `shiftL` 1 .|. o4 `shiftR` 7) .&. 0x1f
i6 = o4 `shiftR` 2 .&. 0x1f
i7 = (o4 `shiftL` 3 .|. o5 `shiftR` 5) .&. 0x1f
i8 = o5 .&. 0x1f
in foldr ((:) . (encodeArray !)) "" [i1, i2, i3, i4, i5, i6, i7, i8] ++ enc os
in enc
decode' :: String
-> [Maybe Word8]
decode' = let
pad n = replicate n $ Just 0
dec [] = []
dec l@[Just eo1, Just eo2] = take 1 . dec $ l ++ pad 6
dec l@[Just eo1, Just eo2, Just eo3, Just eo4] = take 2 . dec $ l ++ pad 4
dec l@[Just eo1, Just eo2, Just eo3, Just eo4, Just eo5] = take 3 . dec $ l ++ pad 3
dec l@[Just eo1, Just eo2, Just eo3, Just eo4, Just eo5, Just eo6, Just eo7] = take 4 . dec $ l ++ pad 1
dec (Just eo1 : Just eo2 : Just eo3 : Just eo4 : Just eo5 : Just eo6 : Just eo7 : Just eo8 : eos) = let
o1 = eo1 `shiftL` 3 .|. eo2 `shiftR` 2
o2 = eo2 `shiftL` 6 .|. eo3 `shiftL` 1 .|. eo4 `shiftR` 4
o3 = eo4 `shiftL` 4 .|. eo5 `shiftR` 1
o4 = eo5 `shiftL` 7 .|. eo6 `shiftL` 2 .|. eo7 `shiftR` 3
o5 = eo7 `shiftL` 5 .|. eo8
in Just o1 : Just o2 : Just o3 : Just o4 : Just o5 : dec eos
dec _ = [Nothing]
in
dec . map (flip M.lookup decodeMap) . takeWhile (/= '=')
decode :: String
-> Maybe [Word8]
decode = sequence . decode'
chop :: Int
-> String
-> [String]
chop = Base32.chop
unchop :: [String]
-> String
unchop = Base32.unchop