-- |
-- Module    : Codec.Binary.Base16
-- Copyright : (c) 2007 Magnus Therning
-- License   : BSD3
--
-- Implemented as specified in RFC 4648 (<http://tools.ietf.org/html/rfc4648>).
--
-- Further documentation and information can be found at
-- <http://www.haskell.org/haskellwiki/Library/Data_encoding>.
module Codec.Binary.Base16
    ( EncIncData(..)
    , EncIncRes(..)
    , encodeInc
    , encode
    , DecIncData(..)
    , DecIncRes(..)
    , decodeInc
    , decode
    , chop
    , unchop
    ) where

import Codec.Binary.Util

import Control.Monad
import Data.Array
import Data.Bits
import Data.Maybe
import Data.Word
import qualified Data.Map as M

-- {{{1 enc/dec map
_encMap :: [(Word8, Char)]
_encMap =
    [ (Word8
0, Char
'0'), (Word8
1, Char
'1'), (Word8
2, Char
'2'), (Word8
3, Char
'3'), (Word8
4, Char
'4')
    , (Word8
5, Char
'5'), (Word8
6, Char
'6'), (Word8
7, Char
'7'), (Word8
8, Char
'8'), (Word8
9, Char
'9')
    , (Word8
10, Char
'A'), (Word8
11, Char
'B'), (Word8
12, Char
'C'), (Word8
13, Char
'D'), (Word8
14, Char
'E')
    , (Word8
15, Char
'F') ]

-- {{{1 encodeArray
encodeArray :: Array Word8 Char
encodeArray :: Array Word8 Char
encodeArray = (Word8, Word8) -> [(Word8, Char)] -> Array Word8 Char
forall i e. Ix i => (i, i) -> [(i, e)] -> Array i e
array (Word8
0, Word8
64) [(Word8, Char)]
_encMap

-- {{{1 decodeMap
decodeMap :: M.Map Char Word8
decodeMap :: Map Char Word8
decodeMap  = [(Char, Word8)] -> Map Char Word8
forall k a. Ord k => [(k, a)] -> Map k a
M.fromList [((Word8, Char) -> Char
forall a b. (a, b) -> b
snd (Word8, Char)
i, (Word8, Char) -> Word8
forall a b. (a, b) -> a
fst (Word8, Char)
i) | (Word8, Char)
i <- [(Word8, Char)]
_encMap]

-- {{{1 encode
-- | Incremental encoder function.
encodeInc :: EncIncData -> EncIncRes String
encodeInc :: EncIncData -> EncIncRes String
encodeInc EncIncData
EDone = String -> EncIncRes String
forall i. i -> EncIncRes i
EFinal []
encodeInc (EChunk [Word8]
os) = String -> (EncIncData -> EncIncRes String) -> EncIncRes String
forall i. i -> (EncIncData -> EncIncRes i) -> EncIncRes i
EPart ([String] -> String
forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat ([String] -> String) -> [String] -> String
forall a b. (a -> b) -> a -> b
$ (Word8 -> String) -> [Word8] -> [String]
forall a b. (a -> b) -> [a] -> [b]
map Word8 -> String
toHex [Word8]
os) EncIncData -> EncIncRes String
encodeInc

-- | Encode data.
encode :: [Word8] -> String
encode :: [Word8] -> String
encode = (EncIncData -> EncIncRes String) -> [Word8] -> String
forall {a}. (EncIncData -> EncIncRes [a]) -> [Word8] -> [a]
encoder EncIncData -> EncIncRes String
encodeInc

-- {{{1 decode
-- | Incremental decoder function.
decodeInc :: DecIncData String -> DecIncRes String
decodeInc :: DecIncData String -> DecIncRes String
decodeInc DecIncData String
d = String -> DecIncData String -> DecIncRes String
dI [] DecIncData String
d
    where
        dec2 :: String -> Maybe Word8
dec2 String
cs = let
                ds :: [Maybe Word8]
ds = (Char -> Maybe Word8) -> String -> [Maybe Word8]
forall a b. (a -> b) -> [a] -> [b]
map ((Char -> Map Char Word8 -> Maybe Word8)
-> Map Char Word8 -> Char -> Maybe Word8
forall a b c. (a -> b -> c) -> b -> a -> c
flip Char -> Map Char Word8 -> Maybe Word8
forall k a. Ord k => k -> Map k a -> Maybe a
M.lookup Map Char Word8
decodeMap) String
cs
                es :: [Word8]
es@[Word8
e1, Word8
e2] = (Maybe Word8 -> Word8) -> [Maybe Word8] -> [Word8]
forall a b. (a -> b) -> [a] -> [b]
map Maybe Word8 -> Word8
forall a. HasCallStack => Maybe a -> a
fromJust [Maybe Word8]
ds
                o :: Word8
o = Word8
e1 Word8 -> Int -> Word8
forall a. Bits a => a -> Int -> a
`shiftL` Int
4 Word8 -> Word8 -> Word8
forall a. Bits a => a -> a -> a
.|. Word8
e2
                allJust :: [Maybe a] -> Bool
allJust = [Bool] -> Bool
forall (t :: * -> *). Foldable t => t Bool -> Bool
and ([Bool] -> Bool) -> ([Maybe a] -> [Bool]) -> [Maybe a] -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Maybe a -> Bool) -> [Maybe a] -> [Bool]
forall a b. (a -> b) -> [a] -> [b]
map Maybe a -> Bool
forall a. Maybe a -> Bool
isJust
            in if [Maybe Word8] -> Bool
forall {a}. [Maybe a] -> Bool
allJust [Maybe Word8]
ds
                then Word8 -> Maybe Word8
forall a. a -> Maybe a
Just Word8
o
                else Maybe Word8
forall a. Maybe a
Nothing

        dI :: String -> DecIncData String -> DecIncRes String
dI [] DecIncData String
DDone = [Word8] -> String -> DecIncRes String
forall i. [Word8] -> i -> DecIncRes i
DFinal [] []
        dI String
lo DecIncData String
DDone = [Word8] -> String -> DecIncRes String
forall i. [Word8] -> i -> DecIncRes i
DFail [] String
lo
        dI String
lo (DChunk String
s) = [Word8] -> String -> DecIncRes String
doDec [] (String
lo String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
s)
            where
                doDec :: [Word8] -> String -> DecIncRes String
doDec [Word8]
acc s' :: String
s'@(Char
c1:Char
c2:String
cs) = DecIncRes String
-> (Word8 -> DecIncRes String) -> Maybe Word8 -> DecIncRes String
forall b a. b -> (a -> b) -> Maybe a -> b
maybe
                    ([Word8] -> String -> DecIncRes String
forall i. [Word8] -> i -> DecIncRes i
DFail [Word8]
acc String
s')
                    (\ Word8
b -> [Word8] -> String -> DecIncRes String
doDec ([Word8]
acc [Word8] -> [Word8] -> [Word8]
forall a. [a] -> [a] -> [a]
++ [Word8
b]) String
cs)
                    (String -> Maybe Word8
dec2 [Char
c1, Char
c2])
                doDec [Word8]
acc String
s = [Word8]
-> (DecIncData String -> DecIncRes String) -> DecIncRes String
forall i. [Word8] -> (DecIncData i -> DecIncRes i) -> DecIncRes i
DPart [Word8]
acc (String -> DecIncData String -> DecIncRes String
dI String
s)

-- | Decode data.
decode :: String -> Maybe [Word8]
decode :: String -> Maybe [Word8]
decode = (DecIncData String -> DecIncRes String) -> String -> Maybe [Word8]
forall i. (DecIncData i -> DecIncRes i) -> i -> Maybe [Word8]
decoder DecIncData String -> DecIncRes String
decodeInc

-- {{{1 chop
-- | Chop up a string in parts.
--
--   The length given is rounded down to the nearest multiple of 2.
chop :: Int     -- ^ length of individual lines
    -> String
    -> [String]
chop :: Int -> String -> [String]
chop Int
n String
"" = []
chop Int
n String
s = let
        enc_len :: Int
enc_len | Int
n Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
< Int
2 = Int
2
                | Bool
otherwise = Int
n Int -> Int -> Int
forall a. Integral a => a -> a -> a
`div` Int
2 Int -> Int -> Int
forall a. Num a => a -> a -> a
* Int
2
    in Int -> String -> String
forall a. Int -> [a] -> [a]
take Int
enc_len String
s String -> [String] -> [String]
forall a. a -> [a] -> [a]
: Int -> String -> [String]
chop Int
n (Int -> String -> String
forall a. Int -> [a] -> [a]
drop Int
enc_len String
s)

-- {{{1 unchop
-- | Concatenate the strings into one long string.
unchop :: [String]
    -> String
unchop :: [String] -> String
unchop = (String -> String -> String) -> String -> [String] -> String
forall a b. (a -> b -> b) -> b -> [a] -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr String -> String -> String
forall a. [a] -> [a] -> [a]
(++) String
""