{-# OPTIONS_JHC -fno-prelude -fffi -funboxed-values #-}
module Jhc.Handle(
    Handle(..),
    IOMode(..),
    stdin,
    stdout,
    stderr,
    withHandle,
    hClose,
    hIsOpen,
    openBinaryPipe,
    openPipe,
    openBinaryFile,
    openFile
    ) where

import Foreign.C.Error
import Foreign.C.String
import Foreign.Marshal.Utils
import Foreign.Storable
import Jhc.Addr
import Jhc.Basics
import Jhc.Enum
import Jhc.Monad
import Jhc.Type.Handle
import Jhc.Order
import Jhc.Show
import Prelude.IO
import System.C.Stdio

deriving instance Eq IOMode
deriving instance Ord IOMode
deriving instance Enum IOMode
--deriving instance Bounded IOMode

instance Show IOMode where
    show ReadMode = "ReadMode"
    show WriteMode = "WriteMode"
    show AppendMode = "AppendMode"
    show ReadWriteMode = "ReadWriteMode"

instance Show Handle where
    showsPrec _ h s = handleName h ++ s

stdin, stdout, stderr :: Handle

{-# INLINE make_builtin #-}
make_builtin mode name std = Handle { handleName = name, handleFile = std, handleIOMode = mode, handleBinary = False, handleIsPipe = False }

stdin = make_builtin ReadMode "stdin" c_stdin
stdout = make_builtin WriteMode "stdout" c_stdout
stderr = make_builtin WriteMode "stderr" c_stderr

foreign import ccall "stdio.h &stdin" c_stdin :: Ptr FILE
foreign import ccall "stdio.h &stdout" c_stdout :: Ptr FILE
foreign import ccall "stdio.h &stderr" c_stderr :: Ptr FILE

withHandle h action = do
    ptr <- peek (handleFile h)
    case ptr == nullPtr of
        True -> fail $ handleName h ++ ": handle  is closed"
        False -> action ptr

hClose h = do
    ptr <- peek (handleFile h)
    case ptr == nullPtr of
        True -> return ()
        False -> do ec <- if handleIsPipe h then c_pclose ptr
                                            else c_fclose ptr
                    if ec /= 0 then fail ("hClose "++handleName h++" failed")
                               else return ()
                    poke (handleFile h) nullPtr

hIsOpen h = do
    ptr <- peek (handleFile h)
    return (ptr /= nullPtr)

throwErrnoFN     :: String	-- ^ textual description of the error location
               -> String
	       -> IO a
throwErrnoFN loc fn  = do
    errno <- getErrno
    ioError (errnoToIOError loc errno Nothing (Just fn))

openFile :: FilePath -> IOMode -> IO Handle
openFile fp m = do
    ptr <- withCString fp $ \cfp -> c_fopen cfp (Ptr (toStr m))
    if ptr == nullPtr then throwErrnoFN "openFile" fp  else do
        pptr <- new ptr
        return Handle { handleBinary = False, handleIsPipe = False, handleName = fp, handleIOMode = m, handleFile = pptr }

openPipe :: String -> IOMode -> IO Handle
openPipe c m = do
    ptr <- withCString c $ \command -> c_popen command (Ptr (toStr m))
    -- if ptr == nullPtr then throwErrnoFN "openPipe" c else do
    pptr <- new ptr
    return Handle { handleBinary = False, handleIsPipe = True, handleName = c, handleIOMode = m, handleFile = pptr }

openBinaryPipe :: String -> IOMode -> IO Handle
openBinaryPipe c m = do
    ptr <- withCString c $ \command -> c_popen command (Ptr (toStr m))
    if ptr == nullPtr then throwErrnoFN "openPipe" c  else do
        pptr <- new ptr
        return Handle { handleBinary = True, handleIsPipe = True, handleName = c, handleIOMode = m, handleFile = pptr }

openBinaryFile :: FilePath -> IOMode -> IO Handle
openBinaryFile fp m = do
    h <- openFile fp m
    return h { handleBinary = True }

toStr x = Addr_ (case x of
    ReadMode -> "r"#
    WriteMode -> "w"#
    AppendMode -> "a"#
    ReadWriteMode -> "r+"#)