{-# language CPP #-}
module Vulkan.CStruct.Utils  ( pokeFixedLengthByteString
                             , pokeFixedLengthNullTerminatedByteString
                             , peekByteStringFromSizedVectorPtr
                             , lowerArrayPtr
                             , advancePtrBytes
                             , FixedArray
                             ) where

import Foreign.Marshal.Array (allocaArray)
import Foreign.Marshal.Utils (copyBytes)
import Foreign.Storable (peekElemOff)
import Foreign.Storable (pokeElemOff)
import GHC.Ptr (castPtr)
import Foreign.Ptr (plusPtr)
import GHC.TypeNats (natVal)
import qualified Data.ByteString (length)
import Data.ByteString (packCString)
import Data.ByteString (packCStringLen)
import Data.ByteString (take)
import Data.ByteString (unpack)
import Data.ByteString.Unsafe (unsafeUseAsCString)
import Data.Vector (ifoldr)
import qualified Data.Vector (length)
import qualified Data.Vector.Generic ((++))
import qualified Data.Vector.Generic (empty)
import qualified Data.Vector.Generic (fromList)
import qualified Data.Vector.Generic (length)
import qualified Data.Vector.Generic (replicate)
import qualified Data.Vector.Generic (snoc)
import qualified Data.Vector.Generic (take)
import Data.Proxy (Proxy(..))
import Foreign.C.Types (CChar(..))
import Foreign.Storable (Storable)
import Foreign.Ptr (Ptr)
import GHC.TypeNats (type(<=))
import GHC.TypeNats (KnownNat)
import Data.Word (Word8)
import Data.ByteString (ByteString)
import GHC.TypeNats (Nat)
import Data.Kind (Type)
import Data.Vector (Vector)
import qualified Data.Vector.Generic (Vector)

-- | An unpopulated type intended to be used as in @'Ptr' (FixedArray n a)@ to
-- indicate that the pointer points to an array of @n@ @a@s
data FixedArray (n :: Nat) (a :: Type)

-- | Store a 'ByteString' in a fixed amount of space inserting a null
-- character at the end and truncating if necessary.
--
-- If the 'ByteString' is not long enough to fill the space the remaining
-- bytes are unchanged
--
-- Note that if the 'ByteString' is exactly long enough the last byte will
-- still be replaced with 0
pokeFixedLengthNullTerminatedByteString
  :: forall n
   . KnownNat n
  => Ptr (FixedArray n CChar)
  -> ByteString
  -> IO ()
pokeFixedLengthNullTerminatedByteString :: Ptr (FixedArray n CChar) -> ByteString -> IO ()
pokeFixedLengthNullTerminatedByteString to :: Ptr (FixedArray n CChar)
to bs :: ByteString
bs =
  ByteString -> (CString -> IO ()) -> IO ()
forall a. ByteString -> (CString -> IO a) -> IO a
unsafeUseAsCString ByteString
bs ((CString -> IO ()) -> IO ()) -> (CString -> IO ()) -> IO ()
forall a b. (a -> b) -> a -> b
$ \from :: CString
from -> do
    let maxLength :: Int
maxLength = Natural -> Int
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Proxy n -> Natural
forall (n :: Nat) (proxy :: Nat -> *).
KnownNat n =>
proxy n -> Natural
natVal (Proxy n
forall k (t :: k). Proxy t
Proxy @n))
        len :: Int
len       = Int -> Int -> Int
forall a. Ord a => a -> a -> a
min Int
maxLength (ByteString -> Int
Data.ByteString.length ByteString
bs)
        end :: Int
end       = Int -> Int -> Int
forall a. Ord a => a -> a -> a
min (Int
maxLength Int -> Int -> Int
forall a. Num a => a -> a -> a
- 1) Int
len
    -- Copy the entire string into the buffer
    CString -> CString -> Int -> IO ()
forall a. Ptr a -> Ptr a -> Int -> IO ()
copyBytes (Ptr (FixedArray n CChar) -> CString
forall a (n :: Nat). Ptr (FixedArray n a) -> Ptr a
lowerArrayPtr Ptr (FixedArray n CChar)
to) CString
from Int
len
    -- Make the last byte (the one following the string, or the
    -- one at the end of the buffer)
    CString -> Int -> CChar -> IO ()
forall a. Storable a => Ptr a -> Int -> a -> IO ()
pokeElemOff (Ptr (FixedArray n CChar) -> CString
forall a (n :: Nat). Ptr (FixedArray n a) -> Ptr a
lowerArrayPtr Ptr (FixedArray n CChar)
to) Int
end 0

-- | Store a 'ByteString' in a fixed amount of space, truncating if necessary.
--
-- If the 'ByteString' is not long enough to fill the space the remaining
-- bytes are unchanged
pokeFixedLengthByteString
  :: forall n
   . KnownNat n
  => Ptr (FixedArray n Word8)
  -> ByteString
  -> IO ()
pokeFixedLengthByteString :: Ptr (FixedArray n Word8) -> ByteString -> IO ()
pokeFixedLengthByteString to :: Ptr (FixedArray n Word8)
to bs :: ByteString
bs = ByteString -> (CString -> IO ()) -> IO ()
forall a. ByteString -> (CString -> IO a) -> IO a
unsafeUseAsCString ByteString
bs ((CString -> IO ()) -> IO ()) -> (CString -> IO ()) -> IO ()
forall a b. (a -> b) -> a -> b
$ \from :: CString
from -> do
  let maxLength :: Int
maxLength = Natural -> Int
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Proxy n -> Natural
forall (n :: Nat) (proxy :: Nat -> *).
KnownNat n =>
proxy n -> Natural
natVal (Proxy n
forall k (t :: k). Proxy t
Proxy @n))
      len :: Int
len       = Int -> Int -> Int
forall a. Ord a => a -> a -> a
min Int
maxLength (ByteString -> Int
Data.ByteString.length ByteString
bs)
  Ptr Word8 -> Ptr Word8 -> Int -> IO ()
forall a. Ptr a -> Ptr a -> Int -> IO ()
copyBytes (Ptr (FixedArray n Word8) -> Ptr Word8
forall a (n :: Nat). Ptr (FixedArray n a) -> Ptr a
lowerArrayPtr Ptr (FixedArray n Word8)
to) (CString -> Ptr Word8
forall a b. Ptr a -> Ptr b
castPtr @CChar @Word8 CString
from) Int
len

-- | Peek a 'ByteString' from a fixed sized array of bytes
peekByteStringFromSizedVectorPtr
  :: forall n
   . KnownNat n
  => Ptr (FixedArray n Word8)
  -> IO ByteString
peekByteStringFromSizedVectorPtr :: Ptr (FixedArray n Word8) -> IO ByteString
peekByteStringFromSizedVectorPtr p :: Ptr (FixedArray n Word8)
p = CStringLen -> IO ByteString
packCStringLen (Ptr (FixedArray n Word8) -> CString
forall a b. Ptr a -> Ptr b
castPtr Ptr (FixedArray n Word8)
p, Natural -> Int
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Proxy n -> Natural
forall (n :: Nat) (proxy :: Nat -> *).
KnownNat n =>
proxy n -> Natural
natVal (Proxy n
forall k (t :: k). Proxy t
Proxy @n)))

-- | Get the pointer to the first element in the array
lowerArrayPtr
  :: forall a n
   . Ptr (FixedArray n a)
  -> Ptr a
lowerArrayPtr :: Ptr (FixedArray n a) -> Ptr a
lowerArrayPtr = Ptr (FixedArray n a) -> Ptr a
forall a b. Ptr a -> Ptr b
castPtr

-- | A type restricted 'plusPtr'
advancePtrBytes :: Ptr a -> Int -> Ptr a
advancePtrBytes :: Ptr a -> Int -> Ptr a
advancePtrBytes = Ptr a -> Int -> Ptr a
forall a b. Ptr a -> Int -> Ptr b
plusPtr