{-# LANGUAGE ForeignFunctionInterface #-}
{-# LANGUAGE EmptyDataDecls #-}

module Haskakafka.Internal where

import Control.Applicative
import Control.Monad
import Data.Word
import Foreign
import Foreign.C.Error
import Foreign.C.String
import Foreign.C.Types
import Haskakafka.InternalEnum
import System.IO
import System.IO.Unsafe (unsafePerformIO)
import System.Posix.IO
import System.Posix.Types

import qualified Data.Map.Strict as Map

#include "rdkafka.h"

type CInt64T = {#type int64_t #}
type CInt32T = {#type int32_t #}

{#pointer *FILE as CFilePtr -> CFile #} 
{#pointer *size_t as CSizePtr -> CSize #}

type Word8Ptr = Ptr Word8
type CCharBufPointer  = Ptr CChar

type RdKafkaMsgFlag = Int
rdKafkaMsgFlagFree :: RdKafkaMsgFlag
rdKafkaMsgFlagFree = 0x1
rdKafkaMsgFlagCopy :: RdKafkaMsgFlag
rdKafkaMsgFlagCopy = 0x2

-- Helper functions
{#fun pure unsafe rd_kafka_version as ^
    {} -> `Int' #}

{#fun pure unsafe rd_kafka_version_str as ^
    {} -> `String' #}

{#fun pure unsafe rd_kafka_err2str as ^
    {enumToCInt `RdKafkaRespErrT'} -> `String' #}

{#fun pure unsafe rd_kafka_errno2err as ^
    {`Int'} -> `RdKafkaRespErrT' cIntToEnum #}


kafkaErrnoString :: IO (String)
kafkaErrnoString = do
    (Errno num) <- getErrno 
    return $ rdKafkaErr2str $ rdKafkaErrno2err (fromIntegral num)

-- Kafka Pointer Types
data RdKafkaConfT
{#pointer *rd_kafka_conf_t as RdKafkaConfTPtr foreign -> RdKafkaConfT #}

data RdKafkaTopicConfT
{#pointer *rd_kafka_topic_conf_t as RdKafkaTopicConfTPtr foreign -> RdKafkaTopicConfT #} 

data RdKafkaT
{#pointer *rd_kafka_t as RdKafkaTPtr foreign -> RdKafkaT #}

data RdKafkaTopicT
{#pointer *rd_kafka_topic_t as RdKafkaTopicTPtr foreign -> RdKafkaTopicT #}

data RdKafkaMessageT = RdKafkaMessageT 
    { err'RdKafkaMessageT :: RdKafkaRespErrT
    , partition'RdKafkaMessageT :: Int
    , len'RdKafkaMessageT :: Int
    , keyLen'RdKafkaMessageT :: Int
    , offset'RdKafkaMessageT :: Int64
    , payload'RdKafkaMessageT :: Word8Ptr
    , key'RdKafkaMessageT :: Word8Ptr
    }
    deriving (Show, Eq)
    
instance Storable RdKafkaMessageT where
    alignment _ = {#alignof rd_kafka_message_t#}
    sizeOf _ = {#sizeof rd_kafka_message_t#}
    peek p = RdKafkaMessageT
        <$> liftM cIntToEnum  ({#get rd_kafka_message_t->err #} p)
        <*> liftM fromIntegral ({#get rd_kafka_message_t->partition #} p)
        <*> liftM fromIntegral ({#get rd_kafka_message_t->len #} p)
        <*> liftM fromIntegral ({#get rd_kafka_message_t->key_len#} p)
        <*> liftM fromIntegral ({#get rd_kafka_message_t->offset#} p)
        <*> liftM castPtr ({#get rd_kafka_message_t->payload#} p)
        <*> liftM castPtr ({#get rd_kafka_message_t->key#} p)
    poke p x = do
      {#set rd_kafka_message_t.err#} p (enumToCInt $ err'RdKafkaMessageT x)
      {#set rd_kafka_message_t.partition#} p (fromIntegral $ partition'RdKafkaMessageT x)
      {#set rd_kafka_message_t.len#} p (fromIntegral $ len'RdKafkaMessageT x)
      {#set rd_kafka_message_t.key_len#} p (fromIntegral $ keyLen'RdKafkaMessageT x)
      {#set rd_kafka_message_t.offset#} p (fromIntegral $ offset'RdKafkaMessageT x)
      {#set rd_kafka_message_t.payload#} p (castPtr $ payload'RdKafkaMessageT x)
      {#set rd_kafka_message_t.key#} p (castPtr $ key'RdKafkaMessageT x)

{#pointer *rd_kafka_message_t as RdKafkaMessageTPtr foreign -> RdKafkaMessageT #}

data RdKafkaMetadataBrokerT = RdKafkaMetadataBrokerT
  { id'RdKafkaMetadataBrokerT  :: Int
  , host'RdKafkaMetadataBrokerT :: CString
  , port'RdKafkaMetadataBrokerT :: Int
  } deriving (Show, Eq)

{#pointer *rd_kafka_metadata_broker_t as RdKafkaMetadataBrokerTPtr -> RdKafkaMetadataBrokerT #}


instance Storable RdKafkaMetadataBrokerT where
  alignment _ = {#alignof rd_kafka_metadata_broker_t#}
  sizeOf _ = {#sizeof rd_kafka_metadata_broker_t#}
  peek p = RdKafkaMetadataBrokerT
    <$> liftM fromIntegral ({#get rd_kafka_metadata_broker_t->id #} p)
    <*> liftM id ({#get rd_kafka_metadata_broker_t->host #} p)
    <*> liftM fromIntegral ({#get rd_kafka_metadata_broker_t->port #} p)
  poke = undefined

data RdKafkaMetadataPartitionT = RdKafkaMetadataPartitionT
  { id'RdKafkaMetadataPartitionT :: Int
  , err'RdKafkaMetadataPartitionT :: RdKafkaRespErrT
  , leader'RdKafkaMetadataPartitionT :: Int
  , replicaCnt'RdKafkaMetadataPartitionT :: Int
  , replicas'RdKafkaMetadataPartitionT :: Ptr CInt32T
  , isrCnt'RdKafkaMetadataPartitionT :: Int
  , isrs'RdKafkaMetadataPartitionT :: Ptr CInt32T
  } deriving (Show, Eq)

instance Storable RdKafkaMetadataPartitionT where
  alignment _ = {#alignof rd_kafka_metadata_partition_t#}
  sizeOf _ = {#sizeof rd_kafka_metadata_partition_t#}
  peek p = RdKafkaMetadataPartitionT
    <$> liftM fromIntegral ({#get rd_kafka_metadata_partition_t->id#} p)
    <*> liftM cIntToEnum ({#get rd_kafka_metadata_partition_t->err#} p)
    <*> liftM fromIntegral ({#get rd_kafka_metadata_partition_t->leader#} p)
    <*> liftM fromIntegral ({#get rd_kafka_metadata_partition_t->replica_cnt#} p)
    <*> liftM castPtr ({#get rd_kafka_metadata_partition_t->replicas#} p)
    <*> liftM fromIntegral ({#get rd_kafka_metadata_partition_t->isr_cnt#} p)
    <*> liftM castPtr ({#get rd_kafka_metadata_partition_t->isrs#} p)

  poke = undefined

{#pointer *rd_kafka_metadata_partition_t as RdKafkaMetadataPartitionTPtr -> RdKafkaMetadataPartitionT #}

data RdKafkaMetadataTopicT = RdKafkaMetadataTopicT
  { topic'RdKafkaMetadataTopicT :: CString
  , partitionCnt'RdKafkaMetadataTopicT :: Int
  , partitions'RdKafkaMetadataTopicT :: Ptr RdKafkaMetadataPartitionT
  , err'RdKafkaMetadataTopicT :: RdKafkaRespErrT
  } deriving (Show, Eq)

instance Storable RdKafkaMetadataTopicT where
  alignment _ = {#alignof rd_kafka_metadata_topic_t#}
  sizeOf _ = {#sizeof rd_kafka_metadata_topic_t #}
  peek p = RdKafkaMetadataTopicT
    <$> liftM id ({#get rd_kafka_metadata_topic_t->topic #} p)
    <*> liftM fromIntegral ({#get rd_kafka_metadata_topic_t->partition_cnt #} p)
    <*> liftM castPtr ({#get rd_kafka_metadata_topic_t->partitions #} p)
    <*> liftM cIntToEnum ({#get rd_kafka_metadata_topic_t->err #} p)
  poke p x = undefined

{#pointer *rd_kafka_metadata_topic_t as RdKafkaMetadataTopicTPtr -> RdKafkaMetadataTopicT #}

data RdKafkaMetadataT = RdKafkaMetadataT
  { brokerCnt'RdKafkaMetadataT :: Int
  , brokers'RdKafkaMetadataT :: RdKafkaMetadataBrokerTPtr
  , topicCnt'RdKafkaMetadataT :: Int
  , topics'RdKafkaMetadataT :: RdKafkaMetadataTopicTPtr
  , origBrokerId'RdKafkaMetadataT :: CInt32T
  } deriving (Show, Eq)

instance Storable RdKafkaMetadataT where
  alignment _ = {#alignof rd_kafka_metadata_t#}
  sizeOf _ = {#sizeof rd_kafka_metadata_t#}
  peek p = RdKafkaMetadataT
    <$> liftM fromIntegral ({#get rd_kafka_metadata_t->broker_cnt #} p)
    <*> liftM castPtr ({#get rd_kafka_metadata_t->brokers #} p)
    <*> liftM fromIntegral ({#get rd_kafka_metadata_t->topic_cnt #} p)
    <*> liftM castPtr ({#get rd_kafka_metadata_t->topics #} p)
    <*> liftM fromIntegral ({#get rd_kafka_metadata_t->orig_broker_id #} p)
  poke p x = undefined

{#pointer *rd_kafka_metadata_t as RdKafkaMetadataTPtr foreign -> RdKafkaMetadataT #}

-- rd_kafka_conf
{#fun unsafe rd_kafka_conf_new as ^
    {} -> `RdKafkaConfTPtr' #}

foreign import ccall unsafe "rdkafka.h &rd_kafka_conf_destroy"
    rdKafkaConfDestroy :: FunPtr (Ptr RdKafkaConfT -> IO ())

{#fun unsafe rd_kafka_conf_dup as ^
    {`RdKafkaConfTPtr'} -> `RdKafkaConfTPtr' #}

newRdKafkaConfT :: IO RdKafkaConfTPtr
newRdKafkaConfT = do
    ret <- rdKafkaConfNew
    addForeignPtrFinalizer rdKafkaConfDestroy ret
    return ret

{#fun unsafe rd_kafka_conf_dump as ^
    {`RdKafkaConfTPtr', castPtr `CSizePtr'} -> `Ptr CString' id #}

{#fun unsafe rd_kafka_conf_dump_free as ^
    {id `Ptr CString', cIntConv `CSize'} -> `()' #}

{#fun unsafe rd_kafka_conf_properties_show as ^
    {`CFilePtr'} -> `()' #}

-- rd_kafka_topic_conf
{#fun unsafe rd_kafka_topic_conf_new as ^
    {} -> `RdKafkaTopicConfTPtr' #}
{#fun unsafe rd_kafka_topic_conf_dup as ^
    {`RdKafkaTopicConfTPtr'} -> `RdKafkaTopicConfTPtr' #}

foreign import ccall unsafe "rdkafka.h &rd_kafka_topic_conf_destroy"
    rdKafkaTopicConfDestroy :: FunPtr (Ptr RdKafkaTopicConfT -> IO ())

newRdKafkaTopicConfT :: IO RdKafkaTopicConfTPtr
newRdKafkaTopicConfT = do
    ret <- rdKafkaTopicConfNew
    addForeignPtrFinalizer rdKafkaTopicConfDestroy ret
    return ret

{#fun unsafe rd_kafka_topic_conf_dump as ^
    {`RdKafkaTopicConfTPtr', castPtr `CSizePtr'} -> `Ptr CString' id #}

-- rd_kafka
{#fun unsafe rd_kafka_new as ^
    {enumToCInt `RdKafkaTypeT', `RdKafkaConfTPtr', id `CCharBufPointer', cIntConv `CSize'} 
    -> `RdKafkaTPtr' #}

foreign import ccall unsafe "rdkafka.h &rd_kafka_destroy"
    rdKafkaDestroy :: FunPtr (Ptr RdKafkaT -> IO ())

nErrorBytes ::  Int
nErrorBytes = 1024 * 8

newRdKafkaT :: RdKafkaTypeT -> RdKafkaConfTPtr -> IO (Either String RdKafkaTPtr)
newRdKafkaT kafkaType confPtr = 
    allocaBytes nErrorBytes $ \charPtr -> do
        duper <- rdKafkaConfDup confPtr
        ret <- rdKafkaNew kafkaType duper charPtr (fromIntegral nErrorBytes)
        withForeignPtr ret $ \realPtr -> do
            if realPtr == nullPtr then peekCString charPtr >>= return . Left
            else do
                addForeignPtrFinalizer rdKafkaDestroy ret
                return $ Right ret

{#fun unsafe rd_kafka_brokers_add as ^
    {`RdKafkaTPtr', `String'} -> `Int' #}

{#fun unsafe rd_kafka_consume_start as rdKafkaConsumeStartInternal
    {`RdKafkaTopicTPtr', cIntConv `CInt32T', cIntConv `CInt64T'} -> `Int' #}

rdKafkaConsumeStart :: RdKafkaTopicTPtr -> Int -> Int64 -> IO (Maybe String)
rdKafkaConsumeStart topicPtr partition offset = do
    i <- rdKafkaConsumeStartInternal topicPtr (fromIntegral partition) (fromIntegral offset)
    case i of 
        -1 -> kafkaErrnoString >>= return . Just
        _ -> return Nothing
{#fun unsafe rd_kafka_consume_stop as rdKafkaConsumeStopInternal
    {`RdKafkaTopicTPtr', cIntConv `CInt32T'} -> `Int' #}

{#fun unsafe rd_kafka_consume as ^
    {`RdKafkaTopicTPtr', cIntConv `CInt32T', `Int'} -> `RdKafkaMessageTPtr' #}

foreign import ccall unsafe "rdkafka.h &rd_kafka_message_destroy"
    rdKafkaMessageDestroy :: FunPtr (Ptr RdKafkaMessageT -> IO ())

rdKafkaConsumeStop :: RdKafkaTopicTPtr -> Int -> IO (Maybe String)
rdKafkaConsumeStop topicPtr partition = do
    i <- rdKafkaConsumeStopInternal topicPtr (fromIntegral partition)
    case i of 
        -1 -> kafkaErrnoString >>= return . Just
        _ -> return Nothing


{#fun unsafe rd_kafka_produce as ^
    {`RdKafkaTopicTPtr', cIntConv `CInt32T', `Int', castPtr `Word8Ptr', 
     cIntConv `CSize', castPtr `Word8Ptr', cIntConv `CSize', castPtr `Word8Ptr'}
     -> `Int' #}

{#fun unsafe rd_kafka_produce_batch as ^
    {`RdKafkaTopicTPtr', cIntConv `CInt32T', `Int', `RdKafkaMessageTPtr', `Int'} -> `Int' #}

castMetadata :: Ptr (Ptr RdKafkaMetadataT) -> Ptr (Ptr ())
castMetadata ptr = castPtr ptr

{#fun unsafe rd_kafka_metadata as ^
   {`RdKafkaTPtr', boolToCInt `Bool', `RdKafkaTopicTPtr', 
    castMetadata `Ptr (Ptr RdKafkaMetadataT)', `Int'}
   -> `RdKafkaRespErrT' cIntToEnum #}

{# fun unsafe rd_kafka_metadata_destroy as ^
   {castPtr `Ptr RdKafkaMetadataT'} -> `()' #}

{#fun unsafe rd_kafka_poll as ^
    {`RdKafkaTPtr', `Int'} -> `Int' #}

{#fun unsafe rd_kafka_outq_len as ^
    {`RdKafkaTPtr'} -> `Int' #}

{#fun unsafe rd_kafka_dump as ^
    {`CFilePtr', `RdKafkaTPtr'} -> `()' #}


-- rd_kafka_topic
{#fun unsafe rd_kafka_topic_new as ^
    {`RdKafkaTPtr', `String', `RdKafkaTopicConfTPtr'} -> `RdKafkaTopicTPtr' #}

foreign import ccall unsafe "rdkafka.h &rd_kafka_topic_destroy"
    rdKafkaTopicDestroy :: FunPtr (Ptr RdKafkaTopicT -> IO ())

newRdKafkaTopicT :: RdKafkaTPtr -> String -> RdKafkaTopicConfTPtr -> IO (Either String RdKafkaTopicTPtr)
newRdKafkaTopicT kafkaPtr topic topicConfPtr = do
    duper <- rdKafkaTopicConfDup topicConfPtr
    ret <- rdKafkaTopicNew kafkaPtr topic duper
    withForeignPtr ret $ \realPtr ->
        if realPtr == nullPtr then kafkaErrnoString >>= return . Left
        else do
            addForeignPtrFinalizer rdKafkaTopicDestroy ret
            return $ Right ret


-- Marshall / Unmarshall
enumToCInt :: Enum a => a -> CInt
enumToCInt = fromIntegral . fromEnum
cIntToEnum :: Enum a => CInt -> a
cIntToEnum = toEnum . fromIntegral
cIntConv :: (Integral a, Num b) =>  a -> b
cIntConv = fromIntegral
boolToCInt :: Bool -> CInt
boolToCInt True = CInt 1
boolToCInt False = CInt 0

-- Handle -> File descriptor

foreign import ccall "" fdopen :: Fd -> CString -> IO (Ptr CFile)
 
handleToCFile :: Handle -> String -> IO (CFilePtr)
handleToCFile h m =
 do iomode <- newCString m
    fd <- handleToFd h
    fdopen fd iomode
 
c_stdin :: IO CFilePtr
c_stdin = handleToCFile stdin "r"
c_stdout :: IO CFilePtr
c_stdout = handleToCFile stdout "w"
c_stderr :: IO CFilePtr
c_stderr = handleToCFile stderr "w"