-- |
-- Module    : Codec.Binary.Yenc
-- Copyright : (c) 2007 Magnus Therning
-- License   : BSD3
--
-- Implementation based on the specification found at
-- <http://yence.sourceforge.net/docs/protocol/version1_3_draft.html>.
--
-- Further documentation and information can be found at
-- <http://www.haskell.org/haskellwiki/Library/Data_encoding>.
module Codec.Binary.Yenc
    ( EncIncData(..)
    , EncIncRes(..)
    , encodeInc
    , encode
    , DecIncData(..)
    , DecIncRes(..)
    , decodeInc
    , decode
    , chop
    , unchop
    ) where

import Codec.Binary.Util

import Data.Word

_criticalsIn :: [Word8]
_criticalsIn = [Word8
0xd6, Word8
0xe0, Word8
0xe3, Word8
0x13]
_equal :: Word8
_equal = Word8
0x3d

-- {{{1 encode
-- | Incremental encoder function.
encodeInc :: EncIncData -> EncIncRes [Word8]
encodeInc :: EncIncData -> EncIncRes [Word8]
encodeInc EncIncData
e = EncIncData -> EncIncRes [Word8]
eI EncIncData
e
    where
        enc :: [Word8] -> [Word8]
enc [] = []
        enc (Word8
o:[Word8]
os)
            | Word8
o Word8 -> [Word8] -> Bool
forall a. Eq a => a -> [a] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` [Word8]
_criticalsIn = Word8
_equal Word8 -> [Word8] -> [Word8]
forall a. a -> [a] -> [a]
: Word8
o Word8 -> Word8 -> Word8
forall a. Num a => a -> a -> a
+ Word8
106 Word8 -> [Word8] -> [Word8]
forall a. a -> [a] -> [a]
: [Word8] -> [Word8]
enc [Word8]
os
            | Bool
otherwise = Word8
o Word8 -> Word8 -> Word8
forall a. Num a => a -> a -> a
+ Word8
42 Word8 -> [Word8] -> [Word8]
forall a. a -> [a] -> [a]
: [Word8] -> [Word8]
enc [Word8]
os

        eI :: EncIncData -> EncIncRes [Word8]
eI EncIncData
EDone = [Word8] -> EncIncRes [Word8]
forall i. i -> EncIncRes i
EFinal []
        eI (EChunk [Word8]
bs) = [Word8] -> (EncIncData -> EncIncRes [Word8]) -> EncIncRes [Word8]
forall i. i -> (EncIncData -> EncIncRes i) -> EncIncRes i
EPart ([Word8] -> [Word8]
enc [Word8]
bs) EncIncData -> EncIncRes [Word8]
encodeInc

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

-- {{{1 decode
-- | Incremental decoder function.
decodeInc :: DecIncData [Word8] -> DecIncRes [Word8]
decodeInc :: DecIncData [Word8] -> DecIncRes [Word8]
decodeInc DecIncData [Word8]
d = [Word8] -> DecIncData [Word8] -> DecIncRes [Word8]
dI [] DecIncData [Word8]
d
    where
        dI :: [Word8] -> DecIncData [Word8] -> DecIncRes [Word8]
dI [] DecIncData [Word8]
DDone = [Word8] -> [Word8] -> DecIncRes [Word8]
forall i. [Word8] -> i -> DecIncRes i
DFinal [] []
        dI [Word8]
lo DecIncData [Word8]
DDone = [Word8] -> [Word8] -> DecIncRes [Word8]
forall i. [Word8] -> i -> DecIncRes i
DFail [] [Word8]
lo
        dI [Word8]
lo (DChunk [Word8]
s) = [Word8] -> [Word8] -> DecIncRes [Word8]
doDec [] ([Word8]
lo [Word8] -> [Word8] -> [Word8]
forall a. [a] -> [a] -> [a]
++ [Word8]
s)
            where
                doDec :: [Word8] -> [Word8] -> DecIncRes [Word8]
doDec [Word8]
acc (Word8
0x3d:Word8
d:[Word8]
ds) = [Word8] -> [Word8] -> DecIncRes [Word8]
doDec ([Word8]
acc [Word8] -> [Word8] -> [Word8]
forall a. [a] -> [a] -> [a]
++ [Word8
d Word8 -> Word8 -> Word8
forall a. Num a => a -> a -> a
+ Word8
150]) [Word8]
ds
                doDec [Word8]
acc (Word8
d:[Word8]
ds) = [Word8] -> [Word8] -> DecIncRes [Word8]
doDec ([Word8]
acc [Word8] -> [Word8] -> [Word8]
forall a. [a] -> [a] -> [a]
++ [Word8
d Word8 -> Word8 -> Word8
forall a. Num a => a -> a -> a
+ Word8
214]) [Word8]
ds
                doDec [Word8]
acc [Word8]
s' = [Word8]
-> (DecIncData [Word8] -> DecIncRes [Word8]) -> DecIncRes [Word8]
forall i. [Word8] -> (DecIncData i -> DecIncRes i) -> DecIncRes i
DPart [Word8]
acc ([Word8] -> DecIncData [Word8] -> DecIncRes [Word8]
dI [Word8]
s')

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

-- {{{1 chop
-- | Chop up a string in parts.
chop :: Int     -- ^ length of individual lines
    -> [Word8]
    -> [[Word8]]
chop :: Int -> [Word8] -> [[Word8]]
chop Int
_ [] = []
chop Int
n [Word8]
ws = let
        _n :: Int
_n = Int -> Int -> Int
forall a. Ord a => a -> a -> a
max Int
n Int
1
        ([Word8]
p1, [Word8]
p2) = Int -> [Word8] -> ([Word8], [Word8])
forall a. Int -> [a] -> ([a], [a])
splitAt Int
_n [Word8]
ws
    in
        if [Word8] -> Word8
forall a. HasCallStack => [a] -> a
last [Word8]
p1 Word8 -> Word8 -> Bool
forall a. Eq a => a -> a -> Bool
== Word8
_equal
            then ([Word8]
p1 [Word8] -> [Word8] -> [Word8]
forall a. [a] -> [a] -> [a]
++ Int -> [Word8] -> [Word8]
forall a. Int -> [a] -> [a]
take Int
1 [Word8]
p2) [Word8] -> [[Word8]] -> [[Word8]]
forall a. a -> [a] -> [a]
: Int -> [Word8] -> [[Word8]]
chop Int
_n (Int -> [Word8] -> [Word8]
forall a. Int -> [a] -> [a]
drop Int
1 [Word8]
p2)
            else [Word8]
p1 [Word8] -> [[Word8]] -> [[Word8]]
forall a. a -> [a] -> [a]
: Int -> [Word8] -> [[Word8]]
chop Int
_n [Word8]
p2

-- {{{1 unchop
-- | Concatenate the strings into one long string.
unchop :: [[Word8]]
    -> [Word8]
unchop :: [[Word8]] -> [Word8]
unchop = [[Word8]] -> [Word8]
forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat