import Text.Highlighting.Illuminate.Types
import Data.Sequence (Seq, (><), (<|), (|>), singleton, viewl, ViewL(..))
import qualified Data.Sequence as Seq (empty)
import qualified Data.Foldable as F
import Data.List (span, break, splitAt, isPrefixOf)
{-# LINE 1 "templates/wrappers.hs" #-}
{-# LINE 1 "templates/wrappers.hs" #-}
{-# LINE 1 "<built-in>" #-}
{-# LINE 1 "<command line>" #-}
{-# LINE 1 "templates/wrappers.hs" #-}
-- -----------------------------------------------------------------------------
-- Alex wrapper code.
--
-- This code is in the PUBLIC DOMAIN; you may copy it freely and use
-- it for any purpose whatsoever.

{-# LINE 18 "templates/wrappers.hs" #-}

-- -----------------------------------------------------------------------------
-- The input type


type AlexInput = (AlexPosn,     -- current position,
                  Char,         -- previous char
                  String)       -- current input string

alexInputPrevChar :: AlexInput -> Char
alexInputPrevChar (p,c,s) = c

alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
alexGetChar (p,c,[]) = Nothing
alexGetChar (p,_,(c:s))  = let p' = alexMove p c in p' `seq`
                                Just (c, (p', c, s))


{-# LINE 51 "templates/wrappers.hs" #-}

-- -----------------------------------------------------------------------------
-- Token positions

-- `Posn' records the location of a token in the input text.  It has three
-- fields: the address (number of chacaters preceding the token), line number
-- and column of a token within the file. `start_pos' gives the position of the
-- start of the file and `eof_pos' a standard encoding for the end of file.
-- `move_pos' calculates the new position after traversing a given character,
-- assuming the usual eight character tab stops.


data AlexPosn = AlexPn !Int !Int !Int
        deriving (Eq,Show)

alexStartPos :: AlexPosn
alexStartPos = AlexPn 0 1 1

alexMove :: AlexPosn -> Char -> AlexPosn
alexMove (AlexPn a l c) '\t' = AlexPn (a+1)  l     (((c+7) `div` 8)*8+1)
alexMove (AlexPn a l c) '\n' = AlexPn (a+1) (l+1)   1
alexMove (AlexPn a l c) _    = AlexPn (a+1)  l     (c+1)


-- -----------------------------------------------------------------------------
-- Default monad


data AlexState = AlexState {
        alex_pos :: !AlexPosn,  -- position at current input location
        alex_inp :: String,     -- the current input
        alex_chr :: !Char,      -- the character before the input
        alex_scd :: !Int        -- the current startcode

      , alex_ust :: AlexUserState -- AlexUserState will be defined in the user program

    }

-- Compile with -funbox-strict-fields for best results!

runAlex :: String -> Alex a -> Either String a
runAlex input (Alex f) 
   = case f (AlexState {alex_pos = alexStartPos,
                        alex_inp = input,       
                        alex_chr = '\n',

                        alex_ust = alexInitUserState,

                        alex_scd = 0}) of Left msg -> Left msg
                                          Right ( _, a ) -> Right a

newtype Alex a = Alex { unAlex :: AlexState -> Either String (AlexState, a) }

instance Monad Alex where
  m >>= k  = Alex $ \s -> case unAlex m s of 
                                Left msg -> Left msg
                                Right (s',a) -> unAlex (k a) s'
  return a = Alex $ \s -> Right (s,a)

alexGetInput :: Alex AlexInput
alexGetInput
 = Alex $ \s@AlexState{alex_pos=pos,alex_chr=c,alex_inp=inp} -> 
        Right (s, (pos,c,inp))

alexSetInput :: AlexInput -> Alex ()
alexSetInput (pos,c,inp)
 = Alex $ \s -> case s{alex_pos=pos,alex_chr=c,alex_inp=inp} of
                  s@(AlexState{}) -> Right (s, ())

alexError :: String -> Alex a
alexError message = Alex $ \s -> Left message

alexGetStartCode :: Alex Int
alexGetStartCode = Alex $ \s@AlexState{alex_scd=sc} -> Right (s, sc)

alexSetStartCode :: Int -> Alex ()
alexSetStartCode sc = Alex $ \s -> Right (s{alex_scd=sc}, ())

alexMonadScan = do
  inp <- alexGetInput
  sc <- alexGetStartCode
  case alexScan inp sc of
    AlexEOF -> alexEOF
    AlexError inp' -> alexError "lexical error"
    AlexSkip  inp' len -> do
        alexSetInput inp'
        alexMonadScan
    AlexToken inp' len action -> do
        alexSetInput inp'
        action inp len

-- -----------------------------------------------------------------------------
-- Useful token actions

type AlexAction result = AlexInput -> Int -> result

-- just ignore this token and scan another one
-- skip :: AlexAction result
skip input len = alexMonadScan

-- ignore this token, but set the start code to a new value
-- begin :: Int -> AlexAction result
begin code input len = do alexSetStartCode code; alexMonadScan

-- perform an action for this token, and set the start code to a new value
-- andBegin :: AlexAction result -> Int -> AlexAction result
(action `andBegin` code) input len = do alexSetStartCode code; action input len

-- token :: (String -> Int -> token) -> AlexAction token
token t input len = return (t input len)



-- -----------------------------------------------------------------------------
-- Monad (with ByteString input)

{-# LINE 251 "templates/wrappers.hs" #-}


-- -----------------------------------------------------------------------------
-- Basic wrapper

{-# LINE 273 "templates/wrappers.hs" #-}


-- -----------------------------------------------------------------------------
-- Basic wrapper, ByteString version

{-# LINE 297 "templates/wrappers.hs" #-}

{-# LINE 322 "templates/wrappers.hs" #-}


-- -----------------------------------------------------------------------------
-- Posn wrapper

-- Adds text positions to the basic model.

{-# LINE 339 "templates/wrappers.hs" #-}


-- -----------------------------------------------------------------------------
-- Posn wrapper, ByteString version

{-# LINE 354 "templates/wrappers.hs" #-}


-- -----------------------------------------------------------------------------
-- GScan wrapper

-- For compatibility with previous versions of Alex, and because we can.

-- -----------------------------------------------------------------------------
-- Custom code for highlighting

alexEOF = return $ singleton (EOF,"")

type AlexUserState = [(Int,TokenType)]  -- a stack of codes and default token types

alexInitUserState = [(0,Plain)]

tok :: TokenType -> AlexInput -> Int -> Alex Tokens
tok t (_,_,s) len = return $ singleton (t, take len s)

getUserState :: Alex AlexUserState
getUserState = Alex $ \s@AlexState{alex_ust=ust} -> Right (s, ust)

setUserState :: AlexUserState -> Alex ()
setUserState newstate = Alex $ \s -> Right (s{alex_ust=newstate}, ())

modifyUserState :: (AlexUserState -> AlexUserState) -> Alex ()
modifyUserState fn = Alex $ \s@AlexState{alex_ust=ust} -> Right (s{alex_ust = fn ust}, ())

plain :: AlexInput -> Int -> Alex Tokens
plain (_,_,s) len = do
  ((_,defaultToken) : _) <- getUserState
  return $ singleton (defaultToken, take len s)

pushContext :: (Int, TokenType) -> b -> Alex b
pushContext newcontext toks = do
  modifyUserState (newcontext :)
  alexSetStartCode $ fst newcontext
  return toks

popContext :: b -> Alex b
popContext toks = do
  contexts <- getUserState
  case contexts of
       []      -> error "Empty contexts stack!"
       [x]     -> return toks
       (x:y:xs) -> do
           setUserState (y:xs)
           alexSetStartCode $ fst y
           return toks

scanForStop :: String -> String -> Int
scanForStop stop ('\n':xs) = 1 +
  let (sps, xs') = span (`elem` " \t") xs
      offset = length sps + length stop
  in  if stop `isPrefixOf` xs'
         then case (takeWhile (`elem` " \t") $ drop (length stop) xs') of
                   ('\n':_)  -> offset
                   []        -> offset
                   _         -> offset + scanForStop stop (drop offset xs')
         else length sps + scanForStop stop xs'
scanForStop stop (_:xs) = 1 + scanForStop stop xs
scanForStop stop [] = 0

hereDoc :: Tokens -> Alex Tokens
hereDoc toks = Alex $ \s ->
  let inp = alex_inp s
      unescape ('\\':x:xs) = x : unescape xs
      unescape (x:xs) = x : unescape xs
      unescape [] = []
      unstring = tail . init . unescape
  in  case viewl toks of
        ((tt,str) :< empty) | tt `elem` [String, VarId] ->
            let stop = if tt == String then unstring str else str
                off = scanForStop stop inp
                (res, newinp) = splitAt off inp
                newpos = foldl alexMove (alex_pos s) res
                s' = s{alex_pos = newpos, alex_inp = newinp, alex_chr = '\n'}
            in  Right (s', toks |> (String, res))
        _                   -> Left "hereDoc expecting String or VarId"

(==>) :: (AlexInput -> Int -> Alex a) -> (a -> Alex b) -> (AlexInput -> Int -> Alex b)
(act1 ==> act2) inp len = do
  res <- act1 inp len
  act2 res

scanner :: Scanner
scanner str = runAlex str $ do
  let loop acc = do toks <- alexMonadScan
                    case viewl toks of
                       ((t,_) :< _) | t == EOF -> return acc
                       _ -> loop (acc >< toks)
  loop Seq.empty

tokenizeWith :: Lexer -> AlexInput -> Int -> Alex Tokens
tokenizeWith lx (_,_,s) len = do
  case (scan lx) (take len s) of
    Left e   -> fail e
    Right r  -> return r

scanWith :: Lexer -> Tokens -> Alex Tokens
scanWith lx toks = Alex $ \s ->
  case (scan lx) (alex_inp s) of
    Left e  -> Left e
    Right r -> Right (s', toks >< r)
      where s' = s{alex_pos = newpos, alex_inp = newinp, alex_chr = lastchar}
            parsed_chars = F.concatMap snd r
            newpos = foldl alexMove (alex_pos s) parsed_chars
            lastchar = if null parsed_chars then '\n' else last parsed_chars
            newinp = drop (length parsed_chars) (alex_inp s)