{-# LANGUAGE GADTs #-}
{-# LANGUAGE RankNTypes #-}
-- | @since 2.2.0
module Distribution.Utils.IOData
    ( -- * 'IOData' & 'IODataMode' type
      IOData (..)
    , IODataMode (..)
    , KnownIODataMode (..)
    , withIOData
    , null
    , hPutContents
    ) where

import qualified Data.ByteString.Lazy as LBS
import           Distribution.Compat.Prelude hiding (null)
import qualified Prelude
import qualified System.IO

-- | Represents either textual or binary data passed via I/O functions
-- which support binary/text mode
--
-- @since 2.2
data IOData
    = IODataText String
    -- ^ How Text gets encoded is usually locale-dependent.
    | IODataBinary LBS.ByteString
    -- ^ Raw binary which gets read/written in binary mode.

withIOData :: IOData -> (forall mode. IODataMode mode -> mode -> r) -> r
withIOData :: forall r.
IOData -> (forall mode. IODataMode mode -> mode -> r) -> r
withIOData (IODataText String
str) forall mode. IODataMode mode -> mode -> r
k   = forall mode. IODataMode mode -> mode -> r
k IODataMode String
IODataModeText String
str
withIOData (IODataBinary ByteString
lbs) forall mode. IODataMode mode -> mode -> r
k = forall mode. IODataMode mode -> mode -> r
k IODataMode ByteString
IODataModeBinary ByteString
lbs

-- | Test whether 'IOData' is empty
null :: IOData -> Bool
null :: IOData -> Bool
null (IODataText String
s)   = forall (t :: * -> *) a. Foldable t => t a -> Bool
Prelude.null String
s
null (IODataBinary ByteString
b) = ByteString -> Bool
LBS.null ByteString
b

instance NFData IOData where
    rnf :: IOData -> ()
rnf (IODataText String
s)     = forall a. NFData a => a -> ()
rnf String
s
    rnf (IODataBinary ByteString
lbs) = forall a. NFData a => a -> ()
rnf ByteString
lbs

-- | @since 2.2
class NFData mode => KnownIODataMode mode where
    -- | 'IOData' Wrapper for 'System.IO.hGetContents'
    --
    -- __Note__: This operation uses lazy I/O. Use 'NFData' to force all
    -- data to be read and consequently the internal file handle to be
    -- closed.
    --
    hGetIODataContents :: System.IO.Handle -> Prelude.IO mode

    toIOData   :: mode -> IOData
    iodataMode :: IODataMode mode

-- | @since 3.2
data IODataMode mode where
    IODataModeText   :: IODataMode String
    IODataModeBinary :: IODataMode LBS.ByteString

instance a ~ Char => KnownIODataMode [a] where
    hGetIODataContents :: Handle -> IO [a]
hGetIODataContents Handle
h = do
        Handle -> Bool -> IO ()
System.IO.hSetBinaryMode Handle
h Bool
False
        Handle -> IO String
System.IO.hGetContents Handle
h

    toIOData :: [a] -> IOData
toIOData = String -> IOData
IODataText
    iodataMode :: IODataMode [a]
iodataMode = IODataMode String
IODataModeText

instance KnownIODataMode LBS.ByteString where
    hGetIODataContents :: Handle -> IO ByteString
hGetIODataContents Handle
h = do
        Handle -> Bool -> IO ()
System.IO.hSetBinaryMode Handle
h Bool
True
        Handle -> IO ByteString
LBS.hGetContents Handle
h

    toIOData :: ByteString -> IOData
toIOData = ByteString -> IOData
IODataBinary
    iodataMode :: IODataMode ByteString
iodataMode = IODataMode ByteString
IODataModeBinary

-- | 'IOData' Wrapper for 'System.IO.hPutStr' and 'System.IO.hClose'
--
-- This is the dual operation ot 'hGetIODataContents',
-- and consequently the handle is closed with `hClose`.
--
-- /Note:/ this performs lazy-IO.
--
-- @since 2.2
hPutContents :: System.IO.Handle -> IOData -> Prelude.IO ()
hPutContents :: Handle -> IOData -> IO ()
hPutContents Handle
h (IODataText String
c) = do
    Handle -> Bool -> IO ()
System.IO.hSetBinaryMode Handle
h Bool
False
    Handle -> String -> IO ()
System.IO.hPutStr Handle
h String
c
    Handle -> IO ()
System.IO.hClose Handle
h
hPutContents Handle
h (IODataBinary ByteString
c) = do
    Handle -> Bool -> IO ()
System.IO.hSetBinaryMode Handle
h Bool
True
    Handle -> ByteString -> IO ()
LBS.hPutStr Handle
h ByteString
c
    Handle -> IO ()
System.IO.hClose Handle
h