{-# LANGUAGE BangPatterns, CPP, MagicHash, UnboxedTuples, UnliftedFFITypes, DeriveDataTypeable #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies #-}

-- |
-- Module      : Data.Primitive.ByteArray
-- Copyright   : (c) Roman Leshchinskiy 2009-2012
-- License     : BSD-style
--
-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
-- Portability : non-portable
--
-- Primitive operations on ByteArrays
--

module Data.Primitive.ByteArray (
  -- * Types
  ByteArray(..), MutableByteArray(..), ByteArray#, MutableByteArray#,

  -- * Allocation
  newByteArray, newPinnedByteArray, newAlignedPinnedByteArray,
  resizeMutableByteArray,

  -- * Element access
  readByteArray, writeByteArray, indexByteArray,

  -- * Constructing
  byteArrayFromList, byteArrayFromListN,

  -- * Folding
  foldrByteArray,

  -- * Freezing and thawing
  unsafeFreezeByteArray, unsafeThawByteArray,

  -- * Block operations
  copyByteArray, copyMutableByteArray,
#if __GLASGOW_HASKELL__ >= 708
  copyByteArrayToAddr, copyMutableByteArrayToAddr,
#endif
  moveByteArray,
  setByteArray, fillByteArray,

  -- * Information
  sizeofByteArray,
  sizeofMutableByteArray, getSizeofMutableByteArray, sameMutableByteArray,
#if __GLASGOW_HASKELL__ >= 802
  isByteArrayPinned, isMutableByteArrayPinned,
#endif
  byteArrayContents, mutableByteArrayContents

) where

import Control.Monad.Primitive
import Control.Monad.ST
import Data.Primitive.Types

import Foreign.C.Types
import Data.Word ( Word8 )
import GHC.Base ( Int(..) )
#if __GLASGOW_HASKELL__ >= 708
import qualified GHC.Exts as Exts ( IsList(..) )
#endif
import GHC.Prim
#if __GLASGOW_HASKELL__ >= 706
    hiding (setByteArray#)
#endif

import Data.Typeable ( Typeable )
import Data.Data ( Data(..) )
import Data.Primitive.Internal.Compat ( isTrue#, mkNoRepType )
import Numeric

#if MIN_VERSION_base(4,9,0)
import qualified Data.Semigroup as SG
import qualified Data.Foldable as F
#endif

#if !(MIN_VERSION_base(4,8,0))
import Data.Monoid (Monoid(..))
#endif

#if __GLASGOW_HASKELL__ >= 802
import GHC.Exts as Exts (isByteArrayPinned#,isMutableByteArrayPinned#)
#endif

#if __GLASGOW_HASKELL__ >= 804
import GHC.Exts (compareByteArrays#)
#else
import System.IO.Unsafe (unsafeDupablePerformIO)
#endif

-- | Byte arrays
data ByteArray = ByteArray ByteArray# deriving ( Typeable )

-- | Mutable byte arrays associated with a primitive state token
data MutableByteArray s = MutableByteArray (MutableByteArray# s)
                                        deriving( Typeable )

-- | Create a new mutable byte array of the specified size in bytes.
newByteArray :: PrimMonad m => Int -> m (MutableByteArray (PrimState m))
{-# INLINE newByteArray #-}
newByteArray (I# n#)
  = primitive (\s# -> case newByteArray# n# s# of
                        (# s'#, arr# #) -> (# s'#, MutableByteArray arr# #))

-- | Create a /pinned/ byte array of the specified size in bytes. The garbage
-- collector is guaranteed not to move it.
newPinnedByteArray :: PrimMonad m => Int -> m (MutableByteArray (PrimState m))
{-# INLINE newPinnedByteArray #-}
newPinnedByteArray (I# n#)
  = primitive (\s# -> case newPinnedByteArray# n# s# of
                        (# s'#, arr# #) -> (# s'#, MutableByteArray arr# #))

-- | Create a /pinned/ byte array of the specified size in bytes and with the
-- given alignment. The garbage collector is guaranteed not to move it.
newAlignedPinnedByteArray
  :: PrimMonad m
  => Int  -- ^ size
  -> Int  -- ^ alignment
  -> m (MutableByteArray (PrimState m))
{-# INLINE newAlignedPinnedByteArray #-}
newAlignedPinnedByteArray (I# n#) (I# k#)
  = primitive (\s# -> case newAlignedPinnedByteArray# n# k# s# of
                        (# s'#, arr# #) -> (# s'#, MutableByteArray arr# #))

-- | Yield a pointer to the array's data. This operation is only safe on
-- /pinned/ byte arrays allocated by 'newPinnedByteArray' or
-- 'newAlignedPinnedByteArray'.
byteArrayContents :: ByteArray -> Addr
{-# INLINE byteArrayContents #-}
byteArrayContents (ByteArray arr#) = Addr (byteArrayContents# arr#)

-- | Yield a pointer to the array's data. This operation is only safe on
-- /pinned/ byte arrays allocated by 'newPinnedByteArray' or
-- 'newAlignedPinnedByteArray'.
mutableByteArrayContents :: MutableByteArray s -> Addr
{-# INLINE mutableByteArrayContents #-}
mutableByteArrayContents (MutableByteArray arr#)
  = Addr (byteArrayContents# (unsafeCoerce# arr#))

-- | Check if the two arrays refer to the same memory block.
sameMutableByteArray :: MutableByteArray s -> MutableByteArray s -> Bool
{-# INLINE sameMutableByteArray #-}
sameMutableByteArray (MutableByteArray arr#) (MutableByteArray brr#)
  = isTrue# (sameMutableByteArray# arr# brr#)

-- | Resize a mutable byte array. The new size is given in bytes.
--
-- This will either resize the array in-place or, if not possible, allocate the
-- contents into a new, unpinned array and copy the original array's contents.
--
-- To avoid undefined behaviour, the original 'MutableByteArray' shall not be
-- accessed anymore after a 'resizeMutableByteArray' has been performed.
-- Moreover, no reference to the old one should be kept in order to allow
-- garbage collection of the original 'MutableByteArray' in case a new
-- 'MutableByteArray' had to be allocated.
--
-- @since 0.6.4.0
resizeMutableByteArray
  :: PrimMonad m => MutableByteArray (PrimState m) -> Int
                 -> m (MutableByteArray (PrimState m))
{-# INLINE resizeMutableByteArray #-}
#if __GLASGOW_HASKELL__ >= 710
resizeMutableByteArray (MutableByteArray arr#) (I# n#)
  = primitive (\s# -> case resizeMutableByteArray# arr# n# s# of
                        (# s'#, arr'# #) -> (# s'#, MutableByteArray arr'# #))
#else
resizeMutableByteArray arr n
  = do arr' <- newByteArray n
       copyMutableByteArray arr' 0 arr 0 (min (sizeofMutableByteArray arr) n)
       return arr'
#endif

-- | Get the size of a byte array in bytes. Unlike 'sizeofMutableByteArray',
-- this function ensures sequencing in the presence of resizing.
getSizeofMutableByteArray
  :: PrimMonad m => MutableByteArray (PrimState m) -> m Int
{-# INLINE getSizeofMutableByteArray #-}
#if __GLASGOW_HASKELL__ >= 801
getSizeofMutableByteArray (MutableByteArray arr#)
  = primitive (\s# -> case getSizeofMutableByteArray# arr# s# of
                        (# s'#, n# #) -> (# s'#, I# n# #))
#else
getSizeofMutableByteArray arr
  = return (sizeofMutableByteArray arr)
#endif

-- | Convert a mutable byte array to an immutable one without copying. The
-- array should not be modified after the conversion.
unsafeFreezeByteArray
  :: PrimMonad m => MutableByteArray (PrimState m) -> m ByteArray
{-# INLINE unsafeFreezeByteArray #-}
unsafeFreezeByteArray (MutableByteArray arr#)
  = primitive (\s# -> case unsafeFreezeByteArray# arr# s# of
                        (# s'#, arr'# #) -> (# s'#, ByteArray arr'# #))

-- | Convert an immutable byte array to a mutable one without copying. The
-- original array should not be used after the conversion.
unsafeThawByteArray
  :: PrimMonad m => ByteArray -> m (MutableByteArray (PrimState m))
{-# INLINE unsafeThawByteArray #-}
unsafeThawByteArray (ByteArray arr#)
  = primitive (\s# -> (# s#, MutableByteArray (unsafeCoerce# arr#) #))

-- | Size of the byte array in bytes.
sizeofByteArray :: ByteArray -> Int
{-# INLINE sizeofByteArray #-}
sizeofByteArray (ByteArray arr#) = I# (sizeofByteArray# arr#)

-- | Size of the mutable byte array in bytes. This function\'s behavior 
-- is undefined if 'resizeMutableByteArray' is ever called on the mutable
-- byte array given as the argument. Consequently, use of this function
-- is discouraged. Prefer 'getSizeofMutableByteArray', which ensures correct
-- sequencing in the presence of resizing.
sizeofMutableByteArray :: MutableByteArray s -> Int
{-# INLINE sizeofMutableByteArray #-}
sizeofMutableByteArray (MutableByteArray arr#) = I# (sizeofMutableByteArray# arr#)

#if __GLASGOW_HASKELL__ >= 802
-- | Check whether or not the byte array is pinned. Pinned byte arrays cannot
--   be moved by the garbage collector. It is safe to use 'byteArrayContents'
--   on such byte arrays. This function is only available when compiling with
--   GHC 8.2 or newer.
--
--   @since 0.6.4.0
isByteArrayPinned :: ByteArray -> Bool
{-# INLINE isByteArrayPinned #-}
isByteArrayPinned (ByteArray arr#) = isTrue# (Exts.isByteArrayPinned# arr#)

-- | Check whether or not the mutable byte array is pinned. This function is
--   only available when compiling with GHC 8.2 or newer.
--
--   @since 0.6.4.0
isMutableByteArrayPinned :: MutableByteArray s -> Bool
{-# INLINE isMutableByteArrayPinned #-}
isMutableByteArrayPinned (MutableByteArray marr#) = isTrue# (Exts.isMutableByteArrayPinned# marr#)
#endif

-- | Read a primitive value from the byte array. The offset is given in
-- elements of type @a@ rather than in bytes.
indexByteArray :: Prim a => ByteArray -> Int -> a
{-# INLINE indexByteArray #-}
indexByteArray (ByteArray arr#) (I# i#) = indexByteArray# arr# i#

-- | Read a primitive value from the byte array. The offset is given in
-- elements of type @a@ rather than in bytes.
readByteArray
  :: (Prim a, PrimMonad m) => MutableByteArray (PrimState m) -> Int -> m a
{-# INLINE readByteArray #-}
readByteArray (MutableByteArray arr#) (I# i#)
  = primitive (readByteArray# arr# i#)

-- | Write a primitive value to the byte array. The offset is given in
-- elements of type @a@ rather than in bytes.
writeByteArray
  :: (Prim a, PrimMonad m) => MutableByteArray (PrimState m) -> Int -> a -> m ()
{-# INLINE writeByteArray #-}
writeByteArray (MutableByteArray arr#) (I# i#) x
  = primitive_ (writeByteArray# arr# i# x)

-- | Right-fold over the elements of a 'ByteArray'.
foldrByteArray :: forall a b. (Prim a) => (a -> b -> b) -> b -> ByteArray -> b
foldrByteArray f z arr = go 0
  where
    go i
      | sizeofByteArray arr > i * sz = f (indexByteArray arr i) (go (i+1))
      | otherwise                    = z
    sz = sizeOf (undefined :: a)

byteArrayFromList :: Prim a => [a] -> ByteArray
byteArrayFromList xs = byteArrayFromListN (length xs) xs

byteArrayFromListN :: Prim a => Int -> [a] -> ByteArray
byteArrayFromListN n ys = runST $ do
    marr <- newByteArray (n * sizeOf (head ys))
    let go !ix [] = if ix == n
          then return ()
          else die "byteArrayFromListN" "list length less than specified size"
        go !ix (x : xs) = if ix < n
          then do
            writeByteArray marr ix x
            go (ix + 1) xs
          else die "byteArrayFromListN" "list length greater than specified size"
    go 0 ys
    unsafeFreezeByteArray marr

unI# :: Int -> Int#
unI# (I# n#) = n#

-- | Copy a slice of an immutable byte array to a mutable byte array.
copyByteArray
  :: PrimMonad m => MutableByteArray (PrimState m)
                                        -- ^ destination array
                 -> Int                 -- ^ offset into destination array
                 -> ByteArray           -- ^ source array
                 -> Int                 -- ^ offset into source array
                 -> Int                 -- ^ number of bytes to copy
                 -> m ()
{-# INLINE copyByteArray #-}
copyByteArray (MutableByteArray dst#) doff (ByteArray src#) soff sz
  = primitive_ (copyByteArray# src# (unI# soff) dst# (unI# doff) (unI# sz))

-- | Copy a slice of a mutable byte array into another array. The two slices
-- may not overlap.
copyMutableByteArray
  :: PrimMonad m => MutableByteArray (PrimState m)
                                        -- ^ destination array
                 -> Int                 -- ^ offset into destination array
                 -> MutableByteArray (PrimState m)
                                        -- ^ source array
                 -> Int                 -- ^ offset into source array
                 -> Int                 -- ^ number of bytes to copy
                 -> m ()
{-# INLINE copyMutableByteArray #-}
copyMutableByteArray (MutableByteArray dst#) doff
                     (MutableByteArray src#) soff sz
  = primitive_ (copyMutableByteArray# src# (unI# soff) dst# (unI# doff) (unI# sz))

#if __GLASGOW_HASKELL__ >= 708
-- | Copy a slice of a byte array to an unmanaged address. These must not
--   overlap. This function is only available when compiling with GHC 7.8
--   or newer.
--
--   @since 0.6.4.0
copyByteArrayToAddr
  :: PrimMonad m
  => Addr -- ^ destination
  -> ByteArray -- ^ source array
  -> Int -- ^ offset into source array
  -> Int -- ^ number of bytes to copy
  -> m ()
{-# INLINE copyByteArrayToAddr #-}
copyByteArrayToAddr (Addr dst#) (ByteArray src#) soff sz
  = primitive_ (copyByteArrayToAddr# src# (unI# soff) dst# (unI# sz))

-- | Copy a slice of a mutable byte array to an unmanaged address. These must
--   not overlap. This function is only available when compiling with GHC 7.8
--   or newer.
--
--   @since 0.6.4.0
copyMutableByteArrayToAddr
  :: PrimMonad m
  => Addr -- ^ destination
  -> MutableByteArray (PrimState m) -- ^ source array
  -> Int -- ^ offset into source array
  -> Int -- ^ number of bytes to copy
  -> m ()
{-# INLINE copyMutableByteArrayToAddr #-}
copyMutableByteArrayToAddr (Addr dst#) (MutableByteArray src#) soff sz
  = primitive_ (copyMutableByteArrayToAddr# src# (unI# soff) dst# (unI# sz))
#endif

-- | Copy a slice of a mutable byte array into another, potentially
-- overlapping array.
moveByteArray
  :: PrimMonad m => MutableByteArray (PrimState m)
                                        -- ^ destination array
                 -> Int                 -- ^ offset into destination array
                 -> MutableByteArray (PrimState m)
                                        -- ^ source array
                 -> Int                 -- ^ offset into source array
                 -> Int                 -- ^ number of bytes to copy
                 -> m ()
{-# INLINE moveByteArray #-}
moveByteArray (MutableByteArray dst#) doff
              (MutableByteArray src#) soff sz
  = unsafePrimToPrim
  $ memmove_mba dst# (fromIntegral doff) src# (fromIntegral soff)
                     (fromIntegral sz)

-- | Fill a slice of a mutable byte array with a value. The offset and length
-- are given in elements of type @a@ rather than in bytes.
setByteArray
  :: (Prim a, PrimMonad m) => MutableByteArray (PrimState m) -- ^ array to fill
                           -> Int                 -- ^ offset into array
                           -> Int                 -- ^ number of values to fill
                           -> a                   -- ^ value to fill with
                           -> m ()
{-# INLINE setByteArray #-}
setByteArray (MutableByteArray dst#) (I# doff#) (I# sz#) x
  = primitive_ (setByteArray# dst# doff# sz# x)

-- | Fill a slice of a mutable byte array with a byte.
fillByteArray
  :: PrimMonad m => MutableByteArray (PrimState m)
                                        -- ^ array to fill
                 -> Int                 -- ^ offset into array
                 -> Int                 -- ^ number of bytes to fill
                 -> Word8               -- ^ byte to fill with
                 -> m ()
{-# INLINE fillByteArray #-}
fillByteArray = setByteArray

foreign import ccall unsafe "primitive-memops.h hsprimitive_memmove"
  memmove_mba :: MutableByteArray# s -> CInt
              -> MutableByteArray# s -> CInt
              -> CSize -> IO ()

instance Data ByteArray where
  toConstr _ = error "toConstr"
  gunfold _ _ = error "gunfold"
  dataTypeOf _ = mkNoRepType "Data.Primitive.ByteArray.ByteArray"

instance Typeable s => Data (MutableByteArray s) where
  toConstr _ = error "toConstr"
  gunfold _ _ = error "gunfold"
  dataTypeOf _ = mkNoRepType "Data.Primitive.ByteArray.MutableByteArray"

-- | @since 0.6.3.0
instance Show ByteArray where
  showsPrec _ ba =
      showString "[" . go 0
    where
      go i
        | i < sizeofByteArray ba = comma . showString "0x" . showHex (indexByteArray ba i :: Word8) . go (i+1)
        | otherwise              = showChar ']'
        where
          comma | i == 0    = id
                | otherwise = showString ", "


compareByteArrays :: ByteArray -> ByteArray -> Int -> Ordering
{-# INLINE compareByteArrays #-}
#if __GLASGOW_HASKELL__ >= 804
compareByteArrays (ByteArray ba1#) (ByteArray ba2#) (I# n#) =
  compare (I# (compareByteArrays# ba1# 0# ba2# 0# n#)) 0
#else
-- Emulate GHC 8.4's 'GHC.Prim.compareByteArrays#'
compareByteArrays (ByteArray ba1#) (ByteArray ba2#) (I# n#)
    = compare (fromCInt (unsafeDupablePerformIO (memcmp_ba ba1# ba2# n))) 0
  where
    n = fromIntegral (I# n#) :: CSize
    fromCInt = fromIntegral :: CInt -> Int

foreign import ccall unsafe "primitive-memops.h hsprimitive_memcmp"
  memcmp_ba :: ByteArray# -> ByteArray# -> CSize -> IO CInt
#endif


sameByteArray :: ByteArray# -> ByteArray# -> Bool
sameByteArray ba1 ba2 =
    case reallyUnsafePtrEquality# (unsafeCoerce# ba1 :: ()) (unsafeCoerce# ba2 :: ()) of
#if __GLASGOW_HASKELL__ >= 708
      r -> isTrue# r
#else
      1# -> True
      0# -> False
#endif

-- | @since 0.6.3.0
instance Eq ByteArray where
  ba1@(ByteArray ba1#) == ba2@(ByteArray ba2#)
    | sameByteArray ba1# ba2# = True
    | n1 /= n2 = False
    | otherwise = compareByteArrays ba1 ba2 n1 == EQ
    where
      n1 = sizeofByteArray ba1
      n2 = sizeofByteArray ba2

-- | Non-lexicographic ordering. This compares the lengths of
-- the byte arrays first and uses a lexicographic ordering if
-- the lengths are equal. Subject to change between major versions.
-- 
-- @since 0.6.3.0
instance Ord ByteArray where
  ba1@(ByteArray ba1#) `compare` ba2@(ByteArray ba2#)
    | sameByteArray ba1# ba2# = EQ
    | n1 /= n2 = n1 `compare` n2
    | otherwise = compareByteArrays ba1 ba2 n1
    where
      n1 = sizeofByteArray ba1
      n2 = sizeofByteArray ba2
-- Note: On GHC 8.4, the primop compareByteArrays# performs a check for pointer
-- equality as a shortcut, so the check here is actually redundant. However, it
-- is included here because it is likely better to check for pointer equality
-- before checking for length equality. Getting the length requires deferencing
-- the pointers, which could cause accesses to memory that is not in the cache.
-- By contrast, a pointer equality check is always extremely cheap.

appendByteArray :: ByteArray -> ByteArray -> ByteArray
appendByteArray a b = runST $ do
  marr <- newByteArray (sizeofByteArray a + sizeofByteArray b)
  copyByteArray marr 0 a 0 (sizeofByteArray a)
  copyByteArray marr (sizeofByteArray a) b 0 (sizeofByteArray b)
  unsafeFreezeByteArray marr

concatByteArray :: [ByteArray] -> ByteArray
concatByteArray arrs = runST $ do
  let len = calcLength arrs 0
  marr <- newByteArray len
  pasteByteArrays marr 0 arrs
  unsafeFreezeByteArray marr

pasteByteArrays :: MutableByteArray s -> Int -> [ByteArray] -> ST s ()
pasteByteArrays !_ !_ [] = return ()
pasteByteArrays !marr !ix (x : xs) = do
  copyByteArray marr ix x 0 (sizeofByteArray x)
  pasteByteArrays marr (ix + sizeofByteArray x) xs

calcLength :: [ByteArray] -> Int -> Int
calcLength [] !n = n
calcLength (x : xs) !n = calcLength xs (sizeofByteArray x + n)

emptyByteArray :: ByteArray
emptyByteArray = runST (newByteArray 0 >>= unsafeFreezeByteArray)

replicateByteArray :: Int -> ByteArray -> ByteArray
replicateByteArray n arr = runST $ do
  marr <- newByteArray (n * sizeofByteArray arr)
  let go i = if i < n
        then do
          copyByteArray marr (i * sizeofByteArray arr) arr 0 (sizeofByteArray arr)
          go (i + 1)
        else return ()
  go 0
  unsafeFreezeByteArray marr

#if MIN_VERSION_base(4,9,0)
instance SG.Semigroup ByteArray where
  (<>) = appendByteArray
  sconcat = mconcat . F.toList
  stimes i arr
    | itgr < 1 = emptyByteArray
    | itgr <= (fromIntegral (maxBound :: Int)) = replicateByteArray (fromIntegral itgr) arr
    | otherwise = error "Data.Primitive.ByteArray#stimes: cannot allocate the requested amount of memory"
    where itgr = toInteger i :: Integer
#endif

instance Monoid ByteArray where
  mempty = emptyByteArray
#if !(MIN_VERSION_base(4,11,0))
  mappend = appendByteArray
#endif
  mconcat = concatByteArray

#if __GLASGOW_HASKELL__ >= 708
-- | @since 0.6.3.0
instance Exts.IsList ByteArray where
  type Item ByteArray = Word8

  toList = foldrByteArray (:) []
  fromList xs = byteArrayFromListN (length xs) xs
  fromListN = byteArrayFromListN
#endif

die :: String -> String -> a
die fun problem = error $ "Data.Primitive.ByteArray." ++ fun ++ ": " ++ problem