{-# OPTIONS_GHC -Wall #-}
module Graphics.Vty.LLInput
    ( Key(..), Modifier(..), Button(..), Event(..), initTermInput ) where

import Data.Char
import Data.Maybe( mapMaybe )
import Data.List( inits )
import Data.Word
import qualified Data.Map as M( fromList, lookup )
import qualified Data.Set as S( fromList, member )

import Codec.Binary.UTF8.Generic (decode)

import Control.Concurrent
import System.Posix.Signals.Exts
import System.Posix.Signals
import System.Posix.Terminal
import System.Console.Terminfo

import System.Posix.IO (stdInput, fdRead, setFdOption, FdOption(..))

-- |Representations of non-modifier keys.
data Key = KEsc | KFun Int | KBackTab | KPrtScr | KPause | KASCII Char | KBS | KIns
         | KHome | KPageUp | KDel | KEnd | KPageDown | KNP5 | KUp | KMenu
         | KLeft | KDown | KRight | KEnter deriving (Eq,Show,Ord)
-- |Modifier keys.  Key codes are interpreted such that users are more likely to
-- have Meta than Alt; for instance on the PC Linux console, 'MMeta' will
-- generally correspond to the physical Alt key.
data Modifier = MShift | MCtrl | MMeta | MAlt deriving (Eq,Show,Ord)
-- |Mouse buttons.  Not yet used.
data Button = BLeft | BMiddle | BRight deriving (Eq,Show,Ord)
-- |Generic events.
data Event = EvKey Key [Modifier] | EvMouse Int Int Button [Modifier]
           | EvResize Int Int deriving (Eq,Show,Ord)

--import GHC.Conc (labelThread)
threadName :: String -> IO ()
--threadName str = myThreadId >>= flip labelThread str
threadName _str = return ()

data KClass = Valid Key [Modifier] | Invalid | Prefix | MisPfx Key [Modifier] [Char]
    deriving(Show)

-- | Set up the terminal for input.  Returns a function which reads key
-- events, and a function for shutting down the terminal access.
initTermInput :: IO (IO Event, IO ())
initTermInput = do
  threadName "main"
  kchan <- newEmptyMVar
  oattr <- getTerminalAttributes stdInput
  let nattr = foldl withoutMode oattr [StartStopOutput, KeyboardInterrupts,
                                       EnableEcho, ProcessInput]
  setTerminalAttributes stdInput nattr Immediately
  terminal <- setupTermFromEnv 

  let iothread :: MVar Event -> IO ()
      iothread chn = threadName "kbd" >> loop [] where
          loop kb = case (classify kb) of
                      Prefix       -> do ch <- getInput
                                         loop (kb ++ [ch])
                      Invalid      -> loop ""
                      MisPfx k m s -> putMVar chn (EvKey k m) >> loop s
                      Valid k m    -> putMVar chn (EvKey k m) >> loop ""
          getInput = do 
              catch 
                  (do
                      setFdOption stdInput NonBlockingRead True
                      (bytes, bytes_read) <- fdRead stdInput 1 
                      if (bytes_read > 0)
                          then return (head bytes)
                          else do
                              threadDelay 50000
                              return '\xFFFE'
                  )
                  (\_ -> do
                      threadDelay 50000
                      return '\xFFFE')
      
      compile :: [[([Char],(Key,[Modifier]))]] -> [Char] -> KClass
      compile lst = cl' where
          lst' = concat lst
          pfx = S.fromList $ concatMap (init . inits . fst) $ lst'
          mlst = M.fromList lst'
          cl' str = case S.member str pfx of
                      True -> Prefix
                      False -> case M.lookup str mlst of
                                 Just (k,m) -> Valid k m
                                 Nothing -> case head $ mapMaybe (\s -> (,) s `fmap` M.lookup s mlst) $ init $ inits str of
                                              (s,(k,m)) -> MisPfx k m (drop (length s) str)
      
      -- ANSI specific bits


      classify, classifyTab :: [Char] -> KClass
      
      classify "\xFFFD" = Invalid 
      classify "\xFFFE" = Invalid
      classify s@(c:_) | ord c >= 0xC2 = 
          if utf8Length (ord c) > length s then Prefix else classifyUtf8 s -- beginning of an utf8 sequence
      classify other = classifyTab other

      classifyUtf8 s = case decode ((map (fromIntegral . ord) s) :: [Word8]) of
          Just (unicodeChar, _) -> Valid (KASCII unicodeChar) []
          _ -> Invalid -- something bad happened; just ignore and continue.
         
      classifyTab = compile (caps_classify_table : ansi_classify_table)
   
      caps_tabls = [("khome", (KHome, [])), 
                    ("kend",  (KEnd,  [])),
                    ("cbt",   (KBackTab, [])),
                    ("kcud1", (KDown,  [])),
                    ("kcuu1", (KUp,  [])),
                    ("kcuf1", (KRight,  [])),
                    ("kcub1", (KLeft,  [])),

                    ("kLFT", (KLeft, [MShift])),
                    ("kRIT", (KRight, [MShift]))
                   ]
   
      caps_classify_table = [(x,y) | (Just x,y) <- map (first (getCapability terminal . tiGetStr)) $ caps_tabls]
      
      ansi_classify_table :: [[([Char], (Key, [Modifier]))]]
      ansi_classify_table =
         [ let k c s = ("\ESC["++c,(s,[])) in [ k "G" KNP5, k "P" KPause,  k "A" KUp, k "B" KDown, k "C" KRight, k "D" KLeft ],

           -- Support for arrows
           [("\ESC[" ++ charCnt ++ show mc++c,(s,m)) 
            | charCnt <- ["1;", ""], -- we can have a count or not
            (m,mc) <- [([MShift],2::Int), ([MCtrl],5), ([MMeta],3), 
                       ([MShift, MCtrl],6), ([MShift, MMeta],4)], -- modifiers and their codes
            (c,s) <- [("A", KUp), ("B", KDown), ("C", KRight), ("D", KLeft)] -- directions and their codes
           ],
           
           let k n s = ("\ESC["++show n++"~",(s,[])) in zipWith k [2::Int,3,5,6] [KIns,KDel,KPageUp,KPageDown],

           -- Support for simple characters.
           [ (x:[],(KASCII x,[])) | x <- map toEnum [0..255] ],

           -- Support for function keys (should use terminfo)
           [ ("\ESC[["++[toEnum(64+i)],(KFun i,[])) | i <- [1..5] ],
           let f ff nrs m = [ ("\ESC["++show n++"~",(KFun (n-(nrs!!0)+ff), m)) | n <- nrs ] in
           concat [ f 6 [17..21] [], f 11 [23,24] [], f 1 [25,26] [MShift], f 3 [28,29] [MShift], f 5 [31..34] [MShift] ],
           [ ('\ESC':[x],(KASCII x,[MMeta])) | x <- '\ESC':'\t':[' ' .. '\DEL'] ],

           -- Ctrl+Char
           [ ([toEnum x],(KASCII y,[MCtrl])) 
              | (x,y) <- zip ([0..31]) ('@':['a'..'z']++['['..'_']),
                y /= 'i' -- Resolve issue #3 where CTRL-i hides TAB.
           ],
           
           -- Ctrl+Meta+Char
           [ ('\ESC':[toEnum x],(KASCII y,[MMeta,MCtrl])) | (x,y) <- zip [0..31] ('@':['a'..'z']++['['..'_']) ],

           -- Special support
           [ -- special support for ESC 
             ("\ESC",(KEsc,[])) , ("\ESC\ESC",(KEsc,[MMeta])), 

             -- Special support for backspace
             ("\DEL",(KBS,[])), ("\ESC\DEL",(KBS,[MMeta])),
             
             -- Special support for Enter
             ("\ESC\^J",(KEnter,[MMeta])), ("\^J",(KEnter,[])) ] 
         ]
   
  iothr <- forkIO $ iothread kchan
  let pokeIO = (Catch $ do threadName "winch|cont"
                           let e = error "(getsize in input layer)"
                           setTerminalAttributes stdInput nattr Immediately
                           putMVar kchan (EvResize e e))
  installHandler windowChange pokeIO Nothing
  installHandler continueProcess pokeIO Nothing
  let uninit = do killThread iothr
                  installHandler windowChange Ignore Nothing
                  installHandler continueProcess Ignore Nothing
                  setTerminalAttributes stdInput oattr Immediately
  return (takeMVar kchan, uninit)

first :: (a -> b) -> (a,c) -> (b,c)
first f (x,y) = (f x, y)

utf8Length :: (Num t, Ord a, Num a) => a -> t
utf8Length c 
    | c < 0x80 = 1
    | c < 0xE0 = 2
    | c < 0xF0 = 3
    | otherwise = 4