-- |
-- Module    : Codec.Binary.Url
-- Copyright : (c) 2009 Magnus Therning
-- License   : BSD3
--
-- URL encoding, sometimes referred to as URI encoding or percent encoding.
-- Implemented based on RFC 3986 (<http://tools.ietf.org/html/rfc3986>).
--
-- Further documentation and information can be found at
-- <http://www.haskell.org/haskellwiki/Library/Data_encoding>.

module Codec.Binary.Url
    ( EncIncData(..)
    , EncIncRes(..)
    , encodeInc
    , encode
    , DecIncData
    , DecIncRes
    , decodeInc
    , decode
    , chop
    , unchop
    ) where

import Codec.Binary.Util

import qualified Data.Map as M
import Data.Char(ord)
import Data.Word(Word8)
import Data.Maybe(isJust, fromJust)

-- {{{1 enc/dec map
_unreservedChars :: [(Word8, Char)]
_unreservedChars = forall a b. [a] -> [b] -> [(a, b)]
zip [Word8
65..Word8
90] String
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        forall a. [a] -> [a] -> [a]
++ forall a b. [a] -> [b] -> [(a, b)]
zip [Word8
97..Word8
122] String
"abcdefghijklmnopqrstuvwxyz"
        forall a. [a] -> [a] -> [a]
++ forall a b. [a] -> [b] -> [(a, b)]
zip [Word8
48..Word8
57] String
"0123456789"
        forall a. [a] -> [a] -> [a]
++ [(Word8
45, Char
'-'), (Word8
95, Char
'_'), (Word8
46, Char
'.'), (Word8
126, Char
'~')]

encodeMap :: M.Map Word8 Char
encodeMap :: Map Word8 Char
encodeMap = forall k a. Ord k => [(k, a)] -> Map k a
M.fromList [(Word8, Char)]
_unreservedChars

decodeMap :: M.Map Char Word8
decodeMap :: Map Char Word8
decodeMap = forall k a. Ord k => [(k, a)] -> Map k a
M.fromList [(Char
b, Word8
a) | (Word8
a, Char
b) <- [(Word8, Char)]
_unreservedChars]

-- {{{1 encode
-- | Incremental decoder function.
encodeInc :: EncIncData -> EncIncRes String
encodeInc :: EncIncData -> EncIncRes String
encodeInc EncIncData
e = EncIncData -> EncIncRes String
eI EncIncData
e
    where
        enc :: [Word8] -> String
enc [] = []
        enc (Word8
o : [Word8]
os) = case (forall k a. Ord k => k -> Map k a -> Maybe a
M.lookup Word8
o Map Word8 Char
encodeMap) of
            Just Char
c -> Char
c forall a. a -> [a] -> [a]
: [Word8] -> String
enc [Word8]
os
            Maybe Char
Nothing -> (Char
'%' forall a. a -> [a] -> [a]
: Word8 -> String
toHex Word8
o) forall a. [a] -> [a] -> [a]
++ [Word8] -> String
enc [Word8]
os

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

-- | Encode data.
encode :: [Word8] -> String
encode :: [Word8] -> String
encode = 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
        dI :: String -> DecIncData String -> DecIncRes String
dI [] DecIncData String
DDone = forall i. [Word8] -> i -> DecIncRes i
DFinal [] []
        dI String
lo DecIncData String
DDone = forall i. [Word8] -> i -> DecIncRes i
DFail [] String
lo
        dI String
lo (DChunk String
s) = [Word8] -> String -> DecIncRes String
doDec [] (String
lo forall a. [a] -> [a] -> [a]
++ String
s)
            where
                doDec :: [Word8] -> String -> DecIncRes String
doDec [Word8]
acc [] = forall i. [Word8] -> (DecIncData i -> DecIncRes i) -> DecIncRes i
DPart [Word8]
acc (String -> DecIncData String -> DecIncRes String
dI [])
                doDec [Word8]
acc s' :: String
s'@(Char
'%':Char
c0:Char
c1:String
cs) = let
                        o :: Maybe Word8
o = String -> Maybe Word8
fromHex [Char
c0, Char
c1]
                    in if forall a. Maybe a -> Bool
isJust Maybe Word8
o
                        then [Word8] -> String -> DecIncRes String
doDec ([Word8]
acc forall a. [a] -> [a] -> [a]
++ [forall a. HasCallStack => Maybe a -> a
fromJust Maybe Word8
o]) String
cs
                        else forall i. [Word8] -> i -> DecIncRes i
DFail [Word8]
acc String
s'
                doDec [Word8]
acc s' :: String
s'@(Char
c:String
cs)
                    | Char
c forall a. Eq a => a -> a -> Bool
/= Char
'%' = [Word8] -> String -> DecIncRes String
doDec ([Word8]
acc forall a. [a] -> [a] -> [a]
++ [forall a b. (Integral a, Num b) => a -> b
fromIntegral forall a b. (a -> b) -> a -> b
$ Char -> Int
ord Char
c]) String
cs
                    | Bool
otherwise = 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 = forall i. (DecIncData i -> DecIncRes i) -> i -> Maybe [Word8]
decoder DecIncData String -> DecIncRes String
decodeInc

-- {{{1 chop
-- | Chop up a string in parts.
chop :: Int     -- ^ length of individual lines
    -> String
    -> [String]
chop :: Int -> String -> [String]
chop Int
n = let
        _n :: Int
_n = forall a. Ord a => a -> a -> a
max Int
1 Int
n
        _chop :: [a] -> [[a]]
_chop [] = []
        _chop [a]
cs = forall a. Int -> [a] -> [a]
take Int
_n [a]
cs forall a. a -> [a] -> [a]
: [a] -> [[a]]
_chop (forall a. Int -> [a] -> [a]
drop Int
_n [a]
cs)
    in forall {a}. [a] -> [[a]]
_chop

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