module RustClient (
    callRustByteChecksum,
    callRustBytePattern,
    callRustMessage,
    callRustSequence,
    callRustSliceSum,
    callRustSummary,
) where

import Control.Exception (bracket)
import Foreign.C.String (CString, peekCString, withCString)
import Foreign.C.Types (CInt (..), CSize (..), CUChar (..), CUInt (..))
import Foreign.Marshal.Alloc (alloca)
import Foreign.Marshal.Array (peekArray, withArrayLen)
import Foreign.Ptr (Ptr, nullPtr)
import Foreign.Storable (peek)
import Interop.Shared (SharedI32Buffer (..), SharedU8Buffer (..), Summary, SharedStats, summaryFromSharedStats)

foreign import ccall unsafe "rust_compute_stats"
    rustComputeStats :: CInt -> CInt -> Ptr SharedStats -> IO CInt

foreign import ccall unsafe "rust_sum_slice"
    rustSumSlice :: Ptr CInt -> CSize -> IO CInt

foreign import ccall unsafe "rust_checksum_bytes"
    rustChecksumBytes :: Ptr CUChar -> CSize -> IO CUInt

foreign import ccall unsafe "rust_make_message"
    rustMakeMessage :: CString -> CInt -> CInt -> IO CString

foreign import ccall unsafe "rust_make_sequence"
    rustMakeSequence :: CInt -> CSize -> Ptr SharedI32Buffer -> IO CInt

foreign import ccall unsafe "rust_make_byte_pattern"
    rustMakeBytePattern :: CUChar -> CSize -> Ptr SharedU8Buffer -> IO CInt

foreign import ccall unsafe "rust_free_string"
    rustFreeString :: CString -> IO ()

foreign import ccall unsafe "rust_free_i32_buffer"
    rustFreeI32Buffer :: Ptr CInt -> CSize -> CSize -> IO ()

foreign import ccall unsafe "rust_free_u8_buffer"
    rustFreeU8Buffer :: Ptr CUChar -> CSize -> CSize -> IO ()

callRustSummary :: Int -> Int -> IO Summary
callRustSummary left right =
    alloca $ \outStats -> do
        status <- rustComputeStats (fromIntegral left) (fromIntegral right) outStats
        if status /= 0
            then fail ("rustComputeStats returned status " ++ show status)
            else summaryFromSharedStats <$> peek outStats

callRustSliceSum :: [Int] -> IO Int
callRustSliceSum values =
    withArrayLen (map fromIntegral values) $ \valueCount valuesPtr ->
        fmap fromIntegral (rustSumSlice valuesPtr (fromIntegral valueCount))

callRustByteChecksum :: [Int] -> IO Int
callRustByteChecksum values =
    withArrayLen (map (fromIntegral . (`mod` 256)) values) $ \valueCount valuesPtr ->
        fmap fromIntegral (rustChecksumBytes valuesPtr (fromIntegral valueCount))

callRustMessage :: String -> Int -> Int -> IO String
callRustMessage name left right =
    withCString name $ \namePtr -> do
        messagePtr <- rustMakeMessage namePtr (fromIntegral left) (fromIntegral right)
        if messagePtr == nullPtr
            then fail "rustMakeMessage returned a null pointer"
            else
                bracket
                    (pure messagePtr)
                    rustFreeString
                    peekCString

callRustSequence :: Int -> Int -> IO [Int]
callRustSequence start count =
    alloca $ \outBuffer -> do
        status <- rustMakeSequence (fromIntegral start) (fromIntegral count) outBuffer
        if status /= 0
            then fail ("rustMakeSequence returned status " ++ show status)
            else do
                buffer <- peek outBuffer
                values <-
                    if sharedBufferPtr buffer == nullPtr
                        then pure []
                        else map fromIntegral <$> peekArray (fromIntegral (sharedBufferLen buffer)) (sharedBufferPtr buffer)
                rustFreeI32Buffer (sharedBufferPtr buffer) (sharedBufferLen buffer) (sharedBufferCap buffer)
                pure values

callRustBytePattern :: Int -> Int -> IO [Int]
callRustBytePattern seed count =
    alloca $ \outBuffer -> do
        status <- rustMakeBytePattern (fromIntegral (seed `mod` 256)) (fromIntegral count) outBuffer
        if status /= 0
            then fail ("rustMakeBytePattern returned status " ++ show status)
            else do
                buffer <- peek outBuffer
                values <-
                    if sharedByteBufferPtr buffer == nullPtr
                        then pure []
                        else map fromIntegral <$> peekArray (fromIntegral (sharedByteBufferLen buffer)) (sharedByteBufferPtr buffer)
                rustFreeU8Buffer (sharedByteBufferPtr buffer) (sharedByteBufferLen buffer) (sharedByteBufferCap buffer)
                pure values