module System.Console.Haskeline.Backend.Win32(
                win32Term,
                win32TermStdin,
                fileRunTerm
                )where


import System.IO
import Foreign
import Foreign.C
import System.Win32 hiding (multiByteToWideChar)
import Graphics.Win32.Misc(getStdHandle, sTD_OUTPUT_HANDLE)
import Data.List(intercalate)
import Control.Concurrent hiding (throwTo)
import Data.Char(isPrint)
import Data.Maybe(mapMaybe)
import Control.Monad

import System.Console.Haskeline.Key
import System.Console.Haskeline.Monads
import System.Console.Haskeline.LineState
import System.Console.Haskeline.Term as Term
import System.Console.Haskeline.Backend.WCWidth

import Data.ByteString.Internal (createAndTrim)
import qualified Data.ByteString as B

#include "win_console.h"

foreign import stdcall "windows.h ReadConsoleInputW" c_ReadConsoleInput
    :: HANDLE -> Ptr () -> DWORD -> Ptr DWORD -> IO Bool
    
foreign import stdcall "windows.h WaitForSingleObject" c_WaitForSingleObject
    :: HANDLE -> DWORD -> IO DWORD

foreign import stdcall "windows.h GetNumberOfConsoleInputEvents"
    c_GetNumberOfConsoleInputEvents :: HANDLE -> Ptr DWORD -> IO Bool

getNumberOfEvents :: HANDLE -> IO Int
getNumberOfEvents h = alloca $ \numEventsPtr -> do
    failIfFalse_ "GetNumberOfConsoleInputEvents"
        $ c_GetNumberOfConsoleInputEvents h numEventsPtr
    fmap fromEnum $ peek numEventsPtr

getEvent :: HANDLE -> Chan Event -> IO Event
getEvent h = keyEventLoop (eventReader h)

eventReader :: HANDLE -> IO [Event]
eventReader h = do
    let waitTime = 500 -- milliseconds
    ret <- c_WaitForSingleObject h waitTime
    yield -- otherwise, the above foreign call causes the loop to never 
          -- respond to the killThread
    if ret /= (#const WAIT_OBJECT_0)
        then eventReader h
        else do
            es <- readEvents h
            return $ mapMaybe processEvent es

consoleHandles :: MaybeT IO Handles
consoleHandles = do
    h_in <- open "CONIN$"
    h_out <- open "CONOUT$"
    return Handles { hIn = h_in, hOut = h_out }
  where
   open file = handle (\(_::IOException) -> mzero) $ liftIO
                $ createFile file (gENERIC_READ .|. gENERIC_WRITE)
                        (fILE_SHARE_READ .|. fILE_SHARE_WRITE) Nothing
                        oPEN_EXISTING 0 Nothing

                       
processEvent :: InputEvent -> Maybe Event
processEvent KeyEvent {keyDown = True, unicodeChar = c, virtualKeyCode = vc,
                    controlKeyState = cstate}
    = fmap (\e -> KeyInput [Key modifier' e]) $ keyFromCode vc `mplus` simpleKeyChar
  where
    simpleKeyChar = guard (c /= '\NUL') >> return (KeyChar c)
    testMod ck = (cstate .&. ck) /= 0
    modifier' = if hasMeta modifier && hasControl modifier
                    then noModifier {hasShift = hasShift modifier}
                    else modifier
    modifier = Modifier {hasMeta = testMod ((#const RIGHT_ALT_PRESSED) 
                                        .|. (#const LEFT_ALT_PRESSED))
                        ,hasControl = testMod ((#const RIGHT_CTRL_PRESSED) 
                                        .|. (#const LEFT_CTRL_PRESSED))
                                    && not (c > '\NUL' && c <= '\031')
                        ,hasShift = testMod (#const SHIFT_PRESSED)
                                    && not (isPrint c)
                        }

processEvent WindowEvent = Just WindowResize
processEvent _ = Nothing

keyFromCode :: WORD -> Maybe BaseKey
keyFromCode (#const VK_BACK) = Just Backspace
keyFromCode (#const VK_LEFT) = Just LeftKey
keyFromCode (#const VK_RIGHT) = Just RightKey
keyFromCode (#const VK_UP) = Just UpKey
keyFromCode (#const VK_DOWN) = Just DownKey
keyFromCode (#const VK_DELETE) = Just Delete
keyFromCode (#const VK_HOME) = Just Home
keyFromCode (#const VK_END) = Just End
keyFromCode (#const VK_PRIOR) = Just PageUp
keyFromCode (#const VK_NEXT) = Just PageDown
-- The Windows console will return '\r' when return is pressed.
keyFromCode (#const VK_RETURN) = Just (KeyChar '\n')
-- TODO: KillLine?
-- TODO: function keys.
keyFromCode _ = Nothing
    
data InputEvent = KeyEvent {keyDown :: BOOL,
                          repeatCount :: WORD,
                          virtualKeyCode :: WORD,
                          virtualScanCode :: WORD,
                          unicodeChar :: Char,
                          controlKeyState :: DWORD}
            -- TODO: WINDOW_BUFFER_SIZE_RECORD
            -- I cant figure out how the user generates them.
           | WindowEvent
           | OtherEvent
                        deriving Show

peekEvent :: Ptr () -> IO InputEvent
peekEvent pRecord = do
    eventType :: WORD <- (#peek INPUT_RECORD, EventType) pRecord
    let eventPtr = (#ptr INPUT_RECORD, Event) pRecord
    case eventType of
        (#const KEY_EVENT) -> getKeyEvent eventPtr
        (#const WINDOW_BUFFER_SIZE_EVENT) -> return WindowEvent
        _ -> return OtherEvent

readEvents :: HANDLE -> IO [InputEvent]
readEvents h = do
    n <- getNumberOfEvents h
    alloca $ \numEventsPtr -> 
        allocaBytes (n * #size INPUT_RECORD) $ \pRecord -> do
            failIfFalse_ "ReadConsoleInput" 
                $ c_ReadConsoleInput h pRecord (toEnum n) numEventsPtr
            numRead <- fmap fromEnum $ peek numEventsPtr
            forM [0..toEnum numRead-1] $ \i -> peekEvent
                $ pRecord `plusPtr` (i * #size INPUT_RECORD)

getKeyEvent :: Ptr () -> IO InputEvent
getKeyEvent p = do
    kDown' <- (#peek KEY_EVENT_RECORD, bKeyDown) p
    repeat' <- (#peek KEY_EVENT_RECORD, wRepeatCount) p
    keyCode <- (#peek KEY_EVENT_RECORD, wVirtualKeyCode) p
    scanCode <- (#peek KEY_EVENT_RECORD, wVirtualScanCode) p
    char :: CWchar <- (#peek KEY_EVENT_RECORD, uChar) p
    state <- (#peek KEY_EVENT_RECORD, dwControlKeyState) p
    return KeyEvent {keyDown = kDown',
                            repeatCount = repeat',
                            virtualKeyCode = keyCode,
                            virtualScanCode = scanCode,
                            unicodeChar = toEnum (fromEnum char),
                            controlKeyState = state}

data Coord = Coord {coordX, coordY :: Int}
                deriving Show
                
#let alignment t = "%lu", (unsigned long)offsetof(struct {char x__; t (y__); }, y__)
instance Storable Coord where
    sizeOf _ = (#size COORD)
    alignment _ = (#alignment COORD)
    peek p = do
        x :: CShort <- (#peek COORD, X) p
        y :: CShort <- (#peek COORD, Y) p
        return Coord {coordX = fromEnum x, coordY = fromEnum y}
    poke p c = do
        (#poke COORD, X) p (toEnum (coordX c) :: CShort)
        (#poke COORD, Y) p (toEnum (coordY c) :: CShort)
                
                            
foreign import ccall "haskeline_SetPosition"
    c_SetPosition :: HANDLE -> Ptr Coord -> IO Bool
    
setPosition :: HANDLE -> Coord -> IO ()
setPosition h c = with c $ failIfFalse_ "SetConsoleCursorPosition" 
                    . c_SetPosition h
                    
foreign import stdcall "windows.h GetConsoleScreenBufferInfo"
    c_GetScreenBufferInfo :: HANDLE -> Ptr () -> IO Bool
    
getPosition :: HANDLE -> IO Coord
getPosition = withScreenBufferInfo $ 
    (#peek CONSOLE_SCREEN_BUFFER_INFO, dwCursorPosition)

withScreenBufferInfo :: (Ptr () -> IO a) -> HANDLE -> IO a
withScreenBufferInfo f h = allocaBytes (#size CONSOLE_SCREEN_BUFFER_INFO)
                                $ \infoPtr -> do
        failIfFalse_ "GetConsoleScreenBufferInfo"
            $ c_GetScreenBufferInfo h infoPtr
        f infoPtr

getBufferSize :: HANDLE -> IO Layout
getBufferSize = withScreenBufferInfo $ \p -> do
    c <- (#peek CONSOLE_SCREEN_BUFFER_INFO, dwSize) p
    return Layout {width = coordX c, height = coordY c}

foreign import stdcall "windows.h WriteConsoleW" c_WriteConsoleW
    :: HANDLE -> Ptr TCHAR -> DWORD -> Ptr DWORD -> Ptr () -> IO Bool

writeConsole :: HANDLE -> String -> IO ()
-- For some reason, Wine returns False when WriteConsoleW is called on an empty
-- string.  Easiest fix: just don't call that function.
writeConsole _ "" = return ()
writeConsole h str = withArray tstr $ \t_arr -> alloca $ \numWritten -> do
    failIfFalse_ "WriteConsole" 
        $ c_WriteConsoleW h t_arr (toEnum $ length str) numWritten nullPtr
  where
    tstr = map (toEnum . fromEnum) str

foreign import stdcall "windows.h MessageBeep" c_messageBeep :: UINT -> IO Bool

messageBeep :: IO ()
messageBeep = c_messageBeep (-1) >> return ()-- intentionally ignore failures.


----------
-- Console mode
foreign import stdcall "windows.h GetConsoleMode" c_GetConsoleMode
    :: HANDLE -> Ptr DWORD -> IO Bool

foreign import stdcall "windows.h SetConsoleMode" c_SetConsoleMode
    :: HANDLE -> DWORD -> IO Bool

withWindowMode :: MonadException m => Handles -> m a -> m a
withWindowMode hs f = do
    let h = hIn hs
    bracket (getConsoleMode h) (setConsoleMode h)
            $ \m -> setConsoleMode h (m .|. (#const ENABLE_WINDOW_INPUT)) >> f
  where
    getConsoleMode h = liftIO $ alloca $ \p -> do
            failIfFalse_ "GetConsoleMode" $ c_GetConsoleMode h p
            peek p
    setConsoleMode h m = liftIO $ failIfFalse_ "SetConsoleMode" $ c_SetConsoleMode h m

----------------------------
-- Drawing

data Handles = Handles { hIn, hOut :: HANDLE }

closeHandles :: Handles -> IO ()
closeHandles hs = closeHandle (hIn hs) >> closeHandle (hOut hs)

newtype Draw m a = Draw {runDraw :: ReaderT Handles m a}
    deriving (Monad,MonadIO,MonadException, MonadReader Handles)

type DrawM a = (MonadIO m, MonadReader Layout m) => Draw m ()

instance MonadTrans Draw where
    lift = Draw . lift

getPos :: MonadIO m => Draw m Coord
getPos = asks hOut >>= liftIO . getPosition
    
setPos :: MonadIO m => Coord -> Draw m ()
setPos c = do
    h <- asks hOut
    liftIO (setPosition h c)

printText :: MonadIO m => String -> Draw m ()
printText txt = do
    h <- asks hOut
    liftIO (writeConsole h txt)
    
printAfter :: [Grapheme] -> DrawM ()
printAfter gs = do
    -- NOTE: you may be tempted to write
    -- do {p <- getPos; printText (...); setPos p}
    -- Unfortunately, that would be WRONG, because if printText wraps
    -- a line at the bottom of the window, causing the window to scroll,
    -- then the old value of p will be incorrect.
    printText (graphemesToString gs)
    movePosLeft gs
    
drawLineDiffWin :: LineChars -> LineChars -> DrawM ()
drawLineDiffWin (xs1,ys1) (xs2,ys2) = case matchInit xs1 xs2 of
    ([],[])     | ys1 == ys2            -> return ()
    (xs1',[])   | xs1' ++ ys1 == ys2    -> movePosLeft xs1'
    ([],xs2')   | ys1 == xs2' ++ ys2    -> movePosRight xs2'
    (xs1',xs2')                         -> do
        movePosLeft xs1'
        let m = gsWidth xs1' + gsWidth ys1 - (gsWidth xs2' + gsWidth ys2)
        let deadText = stringToGraphemes $ replicate m ' '
        printText (graphemesToString xs2')
        printAfter (ys2 ++ deadText)

movePosRight, movePosLeft :: [Grapheme] -> DrawM ()
movePosRight str = do
    p <- getPos
    w <- asks width
    setPos $ moveCoord w p str
  where
    moveCoord _ p [] = p
    moveCoord w p cs = case splitAtWidth (w - coordX p) cs of
                        (_,[],len) | len < w - coordX p -- stayed on same line
                            -> Coord { coordY = coordY p,
                                       coordX = coordX p + len
                                     }
                        (_,cs',_) -- moved to next line
                            -> moveCoord w Coord {
                                            coordY = coordY p + 1,
                                            coordX = 0
                                           } cs'

movePosLeft str = do
    p <- getPos
    w <- asks width
    setPos $ moveCoord w p str
  where
    moveCoord _ p [] = p
    moveCoord w p cs = case splitAtWidth (coordX p) cs of
                        (_,[],len) -- stayed on same line
                            -> Coord { coordY = coordY p,
                                       coordX = coordX p - len
                                     }
                        (_,_:cs',_) -- moved to previous line
                            -> moveCoord w Coord {
                                            coordY = coordY p - 1,
                                            coordX = w-1
                                           } cs'

crlf :: String
crlf = "\r\n"

instance (MonadException m, MonadReader Layout m) => Term (Draw m) where
    drawLineDiff (xs1,ys1) (xs2,ys2) = let
        fixEsc = filter ((/= '\ESC') . baseChar)
        in drawLineDiffWin (fixEsc xs1, fixEsc ys1) (fixEsc xs2, fixEsc ys2)
    -- TODO now that we capture resize events.
    -- first, looks like the cursor stays on the same line but jumps
    -- to the beginning if cut off.
    reposition _ _ = return ()

    printLines [] = return ()
    printLines ls = printText $ intercalate crlf ls ++ crlf
    
    clearLayout = do
        lay <- ask
        setPos (Coord 0 0)
        printText (replicate (width lay * height lay) ' ')
        setPos (Coord 0 0)
    
    moveToNextLine s = do
        movePosRight (snd s)
        printText "\r\n" -- make the console take care of creating a new line
    
    ringBell True = liftIO messageBeep
    ringBell False = return () -- TODO

win32TermStdin :: MaybeT IO RunTerm
win32TermStdin = do
    liftIO (hIsTerminalDevice stdin) >>= guard
    win32Term

win32Term :: MaybeT IO RunTerm
win32Term = do
    hs <- consoleHandles
    ch <- liftIO newChan
    fileRT <- liftIO $ fileRunTerm stdin
    return fileRT {
                            termOps = Left TermOps {
                                getLayout = getBufferSize (hOut hs)
                                , withGetEvent = withWindowMode hs
                                                    . win32WithEvent hs ch
                                , saveUnusedKeys = saveKeys ch
                                , evalTerm = EvalTerm (runReaderT' hs . runDraw)
                                                    (Draw . lift)
                                },
                            closeTerm = closeHandles hs
                        }

win32WithEvent :: MonadException m => Handles -> Chan Event
                                        -> (m Event -> m a) -> m a
win32WithEvent h eventChan f = f $ liftIO $ getEvent (hIn h) eventChan

-- stdin is not a terminal, but we still need to check the right way to output unicode to stdout.
fileRunTerm :: Handle -> IO RunTerm
fileRunTerm h_in = do
    putter <- putOut
    cp <- getCodePage
    return RunTerm {
                    closeTerm = return (),
                    putStrOut = putter,
                    termOps = Right FileOps {
                                inputHandle = h_in,
                                getLocaleChar = getMultiByteChar cp h_in,
                                maybeReadNewline = hMaybeReadNewline h_in,
                                getLocaleLine = Term.hGetLine h_in
                                            >>= liftIO . codePageToUnicode cp
                            }

                    }

-- On Windows, Unicode written to the console must be written with the WriteConsole API call.
-- And to make the API cross-platform consistent, Unicode to a file should be UTF-8.
putOut :: IO (String -> IO ())
putOut = do
    outIsTerm <- hIsTerminalDevice stdout
    if outIsTerm
        then do
            h <- getStdHandle sTD_OUTPUT_HANDLE
            return (writeConsole h)
        else do
            cp <- getCodePage
            return $ \str -> unicodeToCodePage cp str >>= B.putStr >> hFlush stdout



------------------------
-- Multi-byte conversion

foreign import stdcall "WideCharToMultiByte" wideCharToMultiByte
        :: CodePage -> DWORD -> LPCWSTR -> CInt -> LPCSTR -> CInt
                -> LPCSTR -> LPBOOL -> IO CInt

unicodeToCodePage :: CodePage -> String -> IO B.ByteString
unicodeToCodePage cp wideStr = withCWStringLen wideStr $ \(wideBuff, wideLen) -> do
    -- first, ask for the length without filling the buffer.
    outSize <- wideCharToMultiByte cp 0 wideBuff (toEnum wideLen)
                    nullPtr 0 nullPtr nullPtr
    -- then, actually perform the encoding.
    createAndTrim (fromEnum outSize) $ \outBuff -> 
        fmap fromEnum $ wideCharToMultiByte cp 0 wideBuff (toEnum wideLen)
                    (castPtr outBuff) outSize nullPtr nullPtr

foreign import stdcall "MultiByteToWideChar" multiByteToWideChar
        :: CodePage -> DWORD -> LPCSTR -> CInt -> LPWSTR -> CInt -> IO CInt

codePageToUnicode :: CodePage -> B.ByteString -> IO String
codePageToUnicode cp bs = B.useAsCStringLen bs $ \(inBuff, inLen) -> do
    -- first ask for the size without filling the buffer.
    outSize <- multiByteToWideChar cp 0 inBuff (toEnum inLen) nullPtr 0
    -- then, actually perform the decoding.
    allocaArray0 (fromEnum outSize) $ \outBuff -> do
    outSize' <- multiByteToWideChar cp 0 inBuff (toEnum inLen) outBuff outSize
    peekCWStringLen (outBuff, fromEnum outSize')
                

getCodePage :: IO CodePage
getCodePage = do
    conCP <- getConsoleCP
    if conCP > 0
        then return conCP
        else getACP

foreign import stdcall "IsDBCSLeadByteEx" c_IsDBCSLeadByteEx
        :: CodePage -> BYTE -> BOOL

getMultiByteChar :: CodePage -> Handle -> MaybeT IO Char
getMultiByteChar cp h = hWithBinaryMode h loop
  where
    loop = do
        b1 <- hGetByte h
        bs <- if c_IsDBCSLeadByteEx cp b1
                then hGetByte h >>= \b2 -> return [b1,b2]
                else return [b1]
        cs <- liftIO $ codePageToUnicode cp (B.pack bs)
        case cs of
            [] -> loop
            (c:_) -> return c