{-# LANGUAGE ExistentialQuantification,CPP #-}
module Data.Encoding
	(Encoding(..)
	,EncodingException(..)
	,DecodingException(..)
	,recode
	,recodeLazy
	,DynEncoding()
#ifndef USE_HPC
	,encodingFromString
	,encodingFromStringMaybe
#endif
	)
	where

import Data.ByteString (ByteString)
import qualified Data.ByteString.Lazy as Lazy (ByteString)
import Data.Typeable
import Data.Encoding.Base

#ifndef USE_HPC
import Data.Encoding.ASCII
import Data.Encoding.UTF8
import Data.Encoding.UTF16
import Data.Encoding.UTF32
import Data.Encoding.ISO88591
import Data.Encoding.ISO88592
import Data.Encoding.ISO88593
import Data.Encoding.ISO88594
import Data.Encoding.ISO88595
import Data.Encoding.ISO88596
import Data.Encoding.ISO88597
import Data.Encoding.ISO88598
import Data.Encoding.ISO88599
import Data.Encoding.ISO885910
import Data.Encoding.ISO885911
import Data.Encoding.ISO885913
import Data.Encoding.ISO885914
import Data.Encoding.ISO885915
import Data.Encoding.ISO885916
import Data.Encoding.CP1250
import Data.Encoding.CP1251
import Data.Encoding.CP1252
import Data.Encoding.CP1253
import Data.Encoding.CP1254
import Data.Encoding.CP1255
import Data.Encoding.CP1256
import Data.Encoding.CP1257
import Data.Encoding.CP1258
import Data.Encoding.KOI8R
import Data.Encoding.KOI8U
import Data.Encoding.GB18030
import Data.Char
import Text.Regex
#endif

-- | An untyped encoding. Used in 'System.IO.Encoding.getSystemEncoding'.
data DynEncoding = forall t. (Encoding t,Show t,Typeable t,Eq t)
	=> DynEncoding t 

instance Encoding DynEncoding where
	encode (DynEncoding enc) = encode enc
	encodeLazy (DynEncoding enc) = encodeLazy enc
	encodable (DynEncoding enc) = encodable enc
	decode (DynEncoding enc) = decode enc
	decodeLazy (DynEncoding enc) = decodeLazy enc
	decodable (DynEncoding enc) = decodable enc

instance Show DynEncoding where
	show (DynEncoding enc) = "DynEncoding "++show enc

instance Eq DynEncoding where
	(DynEncoding enc1) == (DynEncoding enc2) = case cast enc2 of
		Nothing -> False
		Just renc2 -> enc1 == renc2

-- | This decodes a string from one encoding and encodes it into another.
recode :: (Encoding from,Encoding to) => from -> to -> ByteString -> ByteString
recode enc_f enc_t bs = encode enc_t (decode enc_f bs)

recodeLazy :: (Encoding from,Encoding to) => from -> to -> Lazy.ByteString -> Lazy.ByteString
recodeLazy enc_f enc_t bs = encodeLazy enc_t (decodeLazy enc_f bs)

#ifndef USE_HPC
-- | Like 'encodingFromString' but returns 'Nothing' instead of throwing an error
encodingFromStringMaybe :: String -> Maybe DynEncoding
encodingFromStringMaybe codeName = case (normalizeEncoding codeName) of
    -- ASCII
    "ascii"              -> Just $ DynEncoding ASCII
    "646"                -> Just $ DynEncoding ASCII
    "ansi_x3_4_1968"     -> Just $ DynEncoding ASCII
    "ansi_x3.4_1986"     -> Just $ DynEncoding ASCII
    "cp367"              -> Just $ DynEncoding ASCII
    "csascii"            -> Just $ DynEncoding ASCII
    "ibm367"             -> Just $ DynEncoding ASCII
    "iso646_us"          -> Just $ DynEncoding ASCII
    "iso_646.irv_1991"   -> Just $ DynEncoding ASCII
    "iso_ir_6"           -> Just $ DynEncoding ASCII
    "us"                 -> Just $ DynEncoding ASCII
    "us_ascii"           -> Just $ DynEncoding ASCII
    -- UTF-8
    "utf_8"              -> Just $ DynEncoding UTF8
    "u8"                 -> Just $ DynEncoding UTF8
    "utf"                -> Just $ DynEncoding UTF8
    "utf8"               -> Just $ DynEncoding UTF8
    "utf8_ucs2"          -> Just $ DynEncoding UTF8
    "utf8_ucs4"          -> Just $ DynEncoding UTF8
    -- UTF-16
    "utf_16"             -> Just $ DynEncoding UTF16
    "u16"                -> Just $ DynEncoding UTF16
    "utf16"              -> Just $ DynEncoding UTF16
    -- UTF-32
    "utf_32"             -> Just $ DynEncoding UTF32
    -- KOI8-R
    "koi8_r"             -> Just $ DynEncoding KOI8R
    "cskoi8r"            -> Just $ DynEncoding KOI8R
    -- KOI8-I
    "koi8_u"             -> Just $ DynEncoding KOI8U
    -- ISO-8859-1
    "iso_8859_1"         -> Just $ DynEncoding ISO88591
    "iso8859_1"          -> Just $ DynEncoding ISO88591
    "8859"               -> Just $ DynEncoding ISO88591
    "cp819"              -> Just $ DynEncoding ISO88591
    "csisolatin1"        -> Just $ DynEncoding ISO88591
    "ibm819"             -> Just $ DynEncoding ISO88591
    "iso8859"            -> Just $ DynEncoding ISO88591
    "iso_8859_1_1987"    -> Just $ DynEncoding ISO88591
    "iso_ir_100"         -> Just $ DynEncoding ISO88591
    "l1"                 -> Just $ DynEncoding ISO88591
    "latin"              -> Just $ DynEncoding ISO88591
    "latin1"             -> Just $ DynEncoding ISO88591
    -- ISO-8859-2
    "iso_8859_2"         -> Just $ DynEncoding ISO88592
    "iso8859_2"          -> Just $ DynEncoding ISO88592
    "csisolatin2"        -> Just $ DynEncoding ISO88592
    "iso_8859_2_1987"    -> Just $ DynEncoding ISO88592
    "iso_ir_101"         -> Just $ DynEncoding ISO88592
    "l2"                 -> Just $ DynEncoding ISO88592
    "latin2"             -> Just $ DynEncoding ISO88592
    -- ISO-8859-3
    "iso_8859_3"         -> Just $ DynEncoding ISO88593
    "iso8859_3"          -> Just $ DynEncoding ISO88593
    "csisolatin3"        -> Just $ DynEncoding ISO88593
    "iso_8859_3_1988"    -> Just $ DynEncoding ISO88593
    "iso_ir_109"         -> Just $ DynEncoding ISO88593
    "l3"                 -> Just $ DynEncoding ISO88593
    "latin3"             -> Just $ DynEncoding ISO88593
    --ISO-8859-4
    "iso_8859_4"         -> Just $ DynEncoding ISO88594
    "iso8859_4"          -> Just $ DynEncoding ISO88594
    "csisolatin4"        -> Just $ DynEncoding ISO88594
    "iso_8859_4_1988"    -> Just $ DynEncoding ISO88594
    "iso_ir_110"         -> Just $ DynEncoding ISO88594
    "l4"                 -> Just $ DynEncoding ISO88594
    "latin4"             -> Just $ DynEncoding ISO88594
    --ISO-8859-5
    "iso_8859_5"         -> Just $ DynEncoding ISO88595
    "iso8859_5"          -> Just $ DynEncoding ISO88595
    "csisolatincyrillic" -> Just $ DynEncoding ISO88595
    "cyrillic"           -> Just $ DynEncoding ISO88595
    "iso_8859_5_1988"    -> Just $ DynEncoding ISO88595
    "iso_ir_144"         -> Just $ DynEncoding ISO88595
    -- ISO-8859-6
    "iso_8859_6"         -> Just $ DynEncoding ISO88596
    "iso8859_6"          -> Just $ DynEncoding ISO88596
    "arabic"             -> Just $ DynEncoding ISO88596
    "asmo_708"           -> Just $ DynEncoding ISO88596
    "csisolatinarabic"   -> Just $ DynEncoding ISO88596
    "ecma_114"           -> Just $ DynEncoding ISO88596
    "iso_8859_6_1987"    -> Just $ DynEncoding ISO88596
    "iso_ir_127"         -> Just $ DynEncoding ISO88596
    -- ISO-8859-7
    "iso_8859_7"         -> Just $ DynEncoding ISO88597
    "iso8859_7"          -> Just $ DynEncoding ISO88597
    "csisolatingreek"    -> Just $ DynEncoding ISO88597
    "ecma_118"           -> Just $ DynEncoding ISO88597
    "elot_928"           -> Just $ DynEncoding ISO88597
    "greek"              -> Just $ DynEncoding ISO88597
    "greek8"             -> Just $ DynEncoding ISO88597
    "iso_8859_7_1987"    -> Just $ DynEncoding ISO88597
    "iso_ir_126"         -> Just $ DynEncoding ISO88597
    -- ISO-8859-8
    "iso_8859_8"         -> Just $ DynEncoding ISO88598
    "iso8859_8"          -> Just $ DynEncoding ISO88598
    "csisolatinhebrew"   -> Just $ DynEncoding ISO88598
    "hebrew"             -> Just $ DynEncoding ISO88598
    "iso_8859_8_1988"    -> Just $ DynEncoding ISO88598
    "iso_ir_138"         -> Just $ DynEncoding ISO88598
    -- ISO-8859-9
    "iso_8859_9"         -> Just $ DynEncoding ISO88599
    "iso8859_9"          -> Just $ DynEncoding ISO88599
    "csisolatin5"        -> Just $ DynEncoding ISO88599
    "iso_8859_9_1989"    -> Just $ DynEncoding ISO88599
    "iso_ir_148"         -> Just $ DynEncoding ISO88599
    "l5"                 -> Just $ DynEncoding ISO88599
    "latin5"             -> Just $ DynEncoding ISO88599
    -- ISO-8859-10
    "iso_8859_10"        -> Just $ DynEncoding ISO885910
    "iso8859_10"         -> Just $ DynEncoding ISO885910
    "csisolatin6"        -> Just $ DynEncoding ISO885910
    "iso_8859_10_1992"   -> Just $ DynEncoding ISO885910
    "iso_ir_157"         -> Just $ DynEncoding ISO885910
    "l6"                 -> Just $ DynEncoding ISO885910
    "latin6"             -> Just $ DynEncoding ISO885910
    -- ISO-8859-11
    "iso_8859_11"        -> Just $ DynEncoding ISO885911
    "iso8859_11"         -> Just $ DynEncoding ISO885911
    "thai"               -> Just $ DynEncoding ISO885911
    "iso_8859_11_2001"   -> Just $ DynEncoding ISO885911
    -- ISO-8859-13
    "iso_8859_13"        -> Just $ DynEncoding ISO885913
    "iso8859_13"         -> Just $ DynEncoding ISO885913
    -- ISO-8859-14
    "iso_8859_14"        -> Just $ DynEncoding ISO885914
    "iso8859_14"         -> Just $ DynEncoding ISO885914
    "iso_8859_14_1998"   -> Just $ DynEncoding ISO885914
    "iso_celtic"         -> Just $ DynEncoding ISO885914
    "iso_ir_199"         -> Just $ DynEncoding ISO885914
    "l8"                 -> Just $ DynEncoding ISO885914
    "latin8"             -> Just $ DynEncoding ISO885914
    -- ISO-8859-15
    "iso_8859_15"        -> Just $ DynEncoding ISO885915
    "iso8859_15"         -> Just $ DynEncoding ISO885915
    "latin9"             -> Just $ DynEncoding ISO885915
    "l9"                 -> Just $ DynEncoding ISO885915
    -- ISO-8859-16
    "iso_8859_16"        -> Just $ DynEncoding ISO885916
    "iso8859_16"         -> Just $ DynEncoding ISO885916
    "iso_8859_16_2001"   -> Just $ DynEncoding ISO885916
    "iso_ir_226"         -> Just $ DynEncoding ISO885916
    "l10"                -> Just $ DynEncoding ISO885916
    "latin10"            -> Just $ DynEncoding ISO885916
    -- CP1250
    "cp1250"             -> Just $ DynEncoding CP1250
    "windows_1250"       -> Just $ DynEncoding CP1250
    -- CP1251
    "cp1251"             -> Just $ DynEncoding CP1251
    "windows_1251"       -> Just $ DynEncoding CP1251
    -- CP1252
    "cp1252"             -> Just $ DynEncoding CP1252
    "windows_1252"       -> Just $ DynEncoding CP1252
    -- CP1253
    "cp1253"             -> Just $ DynEncoding CP1253
    "windows_1253"       -> Just $ DynEncoding CP1253
    -- CP1254
    "cp1254"             -> Just $ DynEncoding CP1254
    "windows_1254"       -> Just $ DynEncoding CP1254
    -- CP1255
    "cp1255"             -> Just $ DynEncoding CP1255
    "windows_1255"       -> Just $ DynEncoding CP1255
    -- CP1256
    "cp1256"             -> Just $ DynEncoding CP1256
    "windows_1256"       -> Just $ DynEncoding CP1256
    -- CP1257
    "cp1257"             -> Just $ DynEncoding CP1257
    "windows_1257"       -> Just $ DynEncoding CP1257
    -- CP1258
    "cp1258"             -> Just $ DynEncoding CP1258
    "windows_1258"       -> Just $ DynEncoding CP1258
    -- GB18030
    "gb18030"            -> Just $ DynEncoding GB18030
    "gb18030_2000"       -> Just $ DynEncoding GB18030
    -- defaults to nothing
    _                    -> Nothing
  where
    normalizeEncoding s = map toLower $ subRegex sep s "_"
    sep = mkRegex "[^0-9A-Za-z]+"



-- | Takes the name of an encoding and creates a dynamic encoding from it.
encodingFromString :: String -> DynEncoding
encodingFromString str = maybe
	(error $ "Data.Encoding.encodingFromString: Unknown encoding: "++show str)
	id
	(encodingFromStringMaybe str)
#endif