module Data.Encoding.Preprocessor.Mapping where

import Distribution.Simple.PreProcess
import Distribution.Simple.Utils
import System.IO
import System.FilePath
import Data.List (intersperse,unfoldr)
import Data.Maybe
import Data.Char
import Data.Word
import Data.Ix
import Data.Bits
import Data.Encoding.Preprocessor.Addr
import Data.Array.Static.Builder
import Data.CharMap.Builder

data MappingType
    = ISOMapping
    | JISMapping
    deriving (Eq,Ord,Show,Read)

readTranslation :: Int -> FilePath -> IO [(Integer,Maybe Char)]
readTranslation offset file = do
  cont <- readFile file
  return $ mapMaybe (\ln -> case drop offset ln of
                             [src] -> Just (src,Nothing)
                             [src,trg] -> Just (src,Just $ chr $ fromIntegral trg)
                             _ ->  Nothing) (parseTranslationTable cont)

parseTranslationTable :: String -> [[Integer]]
parseTranslationTable cont = filter (not.null) (map (\ln -> map read (takeWhile ((/='#').head) (words ln))) (lines cont))

{-fillTranslations :: (Ix a,Show a) => a -> a -> [(a,Maybe Char)] -> [(a,Maybe Char)]
fillTranslations f t = merge (range (f,t))
    where
      merge xs [] = map (\x -> (x,Nothing)) xs
      merge [] cs  = error $ "Data.Encoding.Helper.Template.fillTranslations: Character translations out of range: " ++ show cs
      merge (x:xs) (y:ys) = if x < fst y
                            then (x,Nothing):(merge xs (y:ys))
                            else y:(merge xs ys)-}

fillTranslations :: (Enum a,Eq a) => [(a,Maybe Char)] -> (a,a,[Maybe Char])
fillTranslations [] = error "fillTranslations: zero elements"
fillTranslations ((s,c):rest) = let (e,r) = fill' s rest
                                    fill' cur [] = (cur,[])
                                    fill' cur all@((n,c):rest2) = if succ cur == n
                                                                  then (let (e',res) = fill' n rest2
                                                                        in (e',c:res))
                                                                  else (let (e',res) = fill' (succ cur) all
                                                                        in (e',Nothing:res))
                                in (s,e,c:r)

validTranslations :: [(a,Maybe Char)] -> [(a,Char)]
validTranslations = mapMaybe (\(n,mc) -> case mc of
                                          Nothing -> Nothing
                                          Just c -> Just (n,c))

mappingPreprocessor :: PreProcessor
mappingPreprocessor = PreProcessor
                  {platformIndependent = True
                  ,runPreProcessor = \(sbase,sfile) (tbase,tfile) verb -> do
                                       let (dir,fn) = splitFileName sfile
                                       let (bname,ext) = splitExtensions fn
                                       let dirs = splitDirectories dir
                                       let tp = case ext of
                                                  ".mapping" -> ISOMapping
                                                  ".mapping2" -> JISMapping
                                       info verb (tfile++" generated from mapping "++sfile)
                                       preprocessMapping tp (sbase </> sfile) (tbase </> tfile) dirs bname
                  }

preprocessMapping :: MappingType -> FilePath -> FilePath -> [String] -> String -> IO ()
preprocessMapping tp src trg mods name = do
  trans <- readTranslation 0 src
  let mod = concat $ intersperse "." (mods++[name])
  let wsize = case tp of
                ISOMapping -> 1
                JISMapping -> 2
  let bsize = show (wsize*8) ++ (if wsize > 1 then "be" else "")

  --let (larr,off,arr) = staticArray32 trans
  let (sarr,earr,els) = fillTranslations trans
  {-let (lmp,idx,val) = staticMap wsize trans-}
  let arrname = "decoding_array_"++name
  let mpname = "encoding_map_"++name
  let bcheck exp = if sarr/=0 || earr/=255
                   then ("(if "++
                         concat (intersperse "||" $ (if sarr/=0 then ["w<"++show sarr] else [])++(if earr/=255 then ["w>"++show earr] else []))++
                         " then throwException $ IllegalCharacter $ fromIntegral w else "++exp++")"
                        ) else exp
  let mp = buildCharMap (mapMaybe (\(i,c) -> do
                                     rc <- c
                                     return $ SingleMapping 
                                            rc 
                                            (reverse $ unfoldr (\(w,n) -> if n == 0 
                                                                         then Nothing 
                                                                         else Just (fromIntegral w,(w `shiftR` 8,n-1))) (i,wsize))
                             ) trans
                        )
  {-let mp = case wsize of
             1 -> buildStaticMap (mapMaybe (\(i,c) -> case c of
                                                      Nothing -> Nothing
                                                      Just rc -> Just (rc,fromIntegral i::Word8)) trans)
             2 -> buildStaticMap (mapMaybe (\(i,c) -> case c of
                                                      Nothing -> Nothing
                                                      Just rc -> Just (rc,fromIntegral i::Word16)) trans)-}
  writeFile trg $ unlines $
                ["{-# LANGUAGE MagicHash,DeriveDataTypeable #-}"
                ,"module "++mod++"("++name++"(..)) where"
                ,""
                ,"import Data.Encoding.Base"
                ,"import Data.Encoding.ByteSource"
                ,"import Data.Encoding.ByteSink"
                ,"import Data.Encoding.Exception"
                ,"import Data.CharMap"
                ,"import Data.Array.Static"
                ,"import Data.Map.Static"
                ,"import Control.Throws"
                ,"import Prelude hiding (lookup)"
                ,"import Data.Word"
                ,""
                ,"import Data.Typeable"
                ,""
                ,"data "++name++" = "++name
                ,"  deriving (Show,Eq,Typeable)"
                ,""
                ,arrname++" = "++buildStaticArray (sarr,earr) els
                ,""
                ,mpname++" :: CharMap"
                ,mpname++" = "++mp
                ,""
                ,"instance Encoding "++name++" where"
                ,"  decodeChar _ = do"
                ,"    w <- fetchWord"++bsize
                ,"    "++bcheck "return ()"
                ,"    case "++arrname++"!w of"
                ,"      Nothing -> throwException $ IllegalCharacter $ fromIntegral w"
                ,"      Just c -> return c"
                ,"  encodeChar _ c = mapEncode c "++mpname
                ,"  encodeable _ c = mapMember c "++mpname
                ]