{--*-Mode:haskell;coding:utf-8;tab-width:4;c-basic-offset:4;indent-tabs-mode:()-*-
  ex: set ft=haskell fenc=utf-8 sts=4 ts=4 sw=4 et nomod: -}

{-

  MIT License

  Copyright (c) 2017-2020 Michael Truog <mjtruog at protonmail dot com>

  Permission is hereby granted, free of charge, to any person obtaining a
  copy of this software and associated documentation files (the "Software"),
  to deal in the Software without restriction, including without limitation
  the rights to use, copy, modify, merge, publish, distribute, sublicense,
  and/or sell copies of the Software, and to permit persons to whom the
  Software is furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  DEALINGS IN THE SOFTWARE.

 -}

-- | Haskell <https://cloudi.org/api.html#1_Intro CloudI API>.
-- Example usage is available in the
-- <https://cloudi.org/tutorials.html#cloudi_examples integration tests>.

module Foreign.CloudI
    ( Instance.RequestType(..)
    , Instance.Source
    , Instance.Response(..)
    , Instance.Callback
    , Instance.T
    , transIdNull
    , invalidInputError
    , messageDecodingError
    , terminateError
    , Exception
    , Result
    , api
    , threadCount
    , subscribe
    , subscribeCount
    , unsubscribe
    , sendAsync
    , sendSync
    , mcastAsync
    , forward_
    , forwardAsync
    , forwardSync
    , return_
    , returnAsync
    , returnSync
    , recvAsync
    , processIndex
    , processCount
    , processCountMax
    , processCountMin
    , prefix
    , timeoutInitialize
    , timeoutAsync
    , timeoutSync
    , timeoutTerminate
    , poll
    , shutdown
    , threadCreate
    , threadsWait
    , infoKeyValueParse
    , infoKeyValueNew
    ) where

import Prelude hiding (init,length,(<>))
import Data.Bits (shiftL,(.|.))
import Data.Maybe (fromMaybe)
import Data.Typeable (Typeable)
import qualified Control.Exception as Exception
import qualified Control.Concurrent as Concurrent
import qualified Data.Array.IArray as IArray
import qualified Data.Binary.Get as Get
import qualified Data.ByteString as ByteString
import qualified Data.ByteString.Builder as Builder
import qualified Data.ByteString.Char8 as Char8
import qualified Data.ByteString.Lazy as LazyByteString
import qualified Data.List as List
import qualified Data.Map.Strict as Map
import qualified Data.Monoid as Monoid
import qualified Data.Sequence as Sequence
import qualified Data.Time.Clock as Clock
import qualified Data.Time.Clock.POSIX as POSIX (getPOSIXTime)
import qualified Data.Word as Word
import qualified Foreign.C.Types as C
import qualified Foreign.Erlang as Erlang
import qualified Foreign.CloudI.Instance as Instance
import qualified System.IO as SysIO
import qualified System.IO.Error as SysIOErr
import qualified System.IO.Unsafe as Unsafe
import qualified System.Posix.Env as POSIX (getEnv)
type Array = IArray.Array
type Builder = Builder.Builder
type ByteString = ByteString.ByteString
type Get = Get.Get
type Handle = SysIO.Handle
type LazyByteString = LazyByteString.ByteString
type Map = Map.Map
type RequestType = Instance.RequestType
type SomeException = Exception.SomeException
type Source = Instance.Source
type ThreadId = Concurrent.ThreadId
type Word32 = Word.Word32

messageInit :: Word32
messageInit = 1
messageSendAsync :: Word32
messageSendAsync = 2
messageSendSync :: Word32
messageSendSync = 3
messageRecvAsync :: Word32
messageRecvAsync = 4
messageReturnAsync :: Word32
messageReturnAsync = 5
messageReturnSync :: Word32
messageReturnSync = 6
messageReturnsAsync :: Word32
messageReturnsAsync = 7
messageKeepalive :: Word32
messageKeepalive = 8
messageReinit :: Word32
messageReinit = 9
messageSubscribeCount :: Word32
messageSubscribeCount = 10
messageTerm :: Word32
messageTerm = 11

data Message =
      MessageSend (
        RequestType, ByteString, ByteString, ByteString, ByteString,
        Int, Int, ByteString, Source)
    | MessageKeepalive

-- | a null trans_id is used to check for a timeout or
-- to get the oldest response with recv_async
transIdNull :: ByteString
transIdNull = Char8.pack $ List.replicate 16 '\0'

invalidInputError :: String
invalidInputError = "Invalid Input"
messageDecodingError :: String
messageDecodingError = "Message Decoding Error"
terminateError :: String
terminateError = "Terminate"

data Exception s =
      ReturnSync (Instance.T s)
    | ReturnAsync (Instance.T s)
    | ForwardSync (Instance.T s)
    | ForwardAsync (Instance.T s)
    | Terminate (Instance.T s)
    deriving (Show, Typeable)

instance Typeable s => Exception.Exception (Exception s)

printException :: String -> IO ()
printException str =
    SysIO.hPutStrLn SysIO.stderr ("Exception: " ++ str)

printError :: String -> IO ()
printError str =
    SysIO.hPutStrLn SysIO.stderr ("Error: " ++ str)

data CallbackResult s =
      ReturnI (ByteString, ByteString, s, Instance.T s)
    | ForwardI (ByteString, ByteString, ByteString, Int, Int,
                s, Instance.T s)
    | Finished (Instance.T s)

type Result a = Either String a

infixr 4 <>
(<>) :: Monoid.Monoid m => m -> m -> m
(<>) = Monoid.mappend

-- | creates an instance of the CloudI API
api :: Typeable s => Int -> s -> Maybe Bool ->
    IO (Result (Instance.T s))
api threadIndex state terminateReturnValueOpt = do
    SysIO.hSetEncoding SysIO.stdout SysIO.utf8
    SysIO.hSetBuffering SysIO.stdout SysIO.LineBuffering
    SysIO.hSetEncoding SysIO.stderr SysIO.utf8
    SysIO.hSetBuffering SysIO.stderr SysIO.LineBuffering
    protocolValue <- POSIX.getEnv "CLOUDI_API_INIT_PROTOCOL"
    bufferSizeValue <- POSIX.getEnv "CLOUDI_API_INIT_BUFFER_SIZE"
    case (protocolValue, bufferSizeValue) of
        (Just protocol, Just bufferSizeStr) ->
            let terminateReturnValue = fromMaybe True terminateReturnValueOpt
                terminateException = not terminateReturnValue
                bufferSize = read bufferSizeStr :: Int
                fd = C.CInt $ fromIntegral (threadIndex + 3)
                useHeader = protocol /= "udp"
                timeoutTerminate' = 10 -- TIMEOUT_TERMINATE_MIN
                initTerms = Erlang.OtpErlangAtom (Char8.pack "init")
            in
            case Erlang.termToBinary initTerms (-1) of
                Left err ->
                    return $ Left $ show err
                Right initBinary -> do
                    api0 <- Instance.make state terminateException
                        protocol fd useHeader bufferSize timeoutTerminate'
                    send api0 initBinary
                    result <- pollRequest api0 (-1) False
                    case result of
                        Left err ->
                            -- Terminate exception not used here
                            return $ Left err
                        Right (_, api1) ->
                            return $ Right api1
        (_, _) ->
            return $ Left invalidInputError

-- | returns the thread count from the service configuration
threadCount :: IO (Result Int)
threadCount = do
    threadCountValue <- POSIX.getEnv "CLOUDI_API_INIT_THREAD_COUNT"
    case threadCountValue of
        Nothing ->
            return $ Left invalidInputError
        Just threadCountStr ->
            return $ Right (read threadCountStr :: Int)

-- | subscribes to a service name pattern with a callback
subscribe :: Instance.T s -> ByteString -> Instance.Callback s ->
    IO (Result (Instance.T s))
subscribe api0 pattern f =
    let subscribeTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "subscribe")
            , Erlang.OtpErlangString pattern]
    in
    case Erlang.termToBinary subscribeTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right subscribeBinary -> do
            send api0 subscribeBinary
            return $ Right $ Instance.callbacksAdd api0 pattern f

-- | returns the number of subscriptions for a single service name pattern
subscribeCount :: Typeable s => Instance.T s -> ByteString ->
    IO (Result (Int, Instance.T s))
subscribeCount api0@Instance.T{
      Instance.terminateException = terminateException}
    pattern =
    let subscribeCountTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "subscribe_count")
            , Erlang.OtpErlangString pattern]
    in
    case Erlang.termToBinary subscribeCountTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right subscribeCountBinary -> do
            send api0 subscribeCountBinary
            result <- pollRequest api0 (-1) False
            case result of
                Left err ->
                    if err == terminateError && terminateException then
                        Exception.throwIO $ Terminate api0
                    else
                        return $ Left err
                Right (_, api1@Instance.T{Instance.subscribeCount = count}) ->
                    return $ Right (count, api1)

-- | unsubscribes from a service name pattern once
unsubscribe :: Instance.T s -> ByteString ->
    IO (Result (Instance.T s))
unsubscribe api0 pattern =
    let unsubscribeTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "unsubscribe")
            , Erlang.OtpErlangString pattern]
    in
    case Erlang.termToBinary unsubscribeTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right unsubscribeBinary -> do
            send api0 unsubscribeBinary
            return $ Right $ Instance.callbacksRemove api0 pattern

-- | sends an asynchronous service request
sendAsync :: Typeable s => Instance.T s -> ByteString -> ByteString ->
    Maybe Int -> Maybe ByteString -> Maybe Int ->
    IO (Result (ByteString, Instance.T s))
sendAsync api0@Instance.T{
      Instance.terminateException = terminateException
    , Instance.timeoutAsync = timeoutAsync'
    , Instance.priorityDefault = priorityDefault}
    name request timeoutOpt requestInfoOpt priorityOpt =
    let timeout = fromMaybe timeoutAsync' timeoutOpt
        requestInfo = fromMaybe ByteString.empty requestInfoOpt
        priority = fromMaybe priorityDefault priorityOpt
        sendAsyncTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "send_async")
            , Erlang.OtpErlangString name
            , Erlang.OtpErlangBinary requestInfo
            , Erlang.OtpErlangBinary request
            , Erlang.OtpErlangInteger timeout
            , Erlang.OtpErlangInteger priority]
    in
    case Erlang.termToBinary sendAsyncTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right sendAsyncBinary -> do
            send api0 sendAsyncBinary
            result <- pollRequest api0 (-1) False
            case result of
                Left err ->
                    if err == terminateError && terminateException then
                        Exception.throwIO $ Terminate api0
                    else
                        return $ Left err
                Right (_, api1@Instance.T{Instance.transId = transId}) ->
                    return $ Right (transId, api1)

-- | sends a synchronous service request
sendSync :: Typeable s => Instance.T s -> ByteString -> ByteString ->
    Maybe Int -> Maybe ByteString -> Maybe Int ->
    IO (Result (ByteString, ByteString, ByteString, Instance.T s))
sendSync api0@Instance.T{
      Instance.terminateException = terminateException
    , Instance.timeoutSync = timeoutSync'
    , Instance.priorityDefault = priorityDefault}
    name request timeoutOpt requestInfoOpt priorityOpt =
    let timeout = fromMaybe timeoutSync' timeoutOpt
        requestInfo = fromMaybe ByteString.empty requestInfoOpt
        priority = fromMaybe priorityDefault priorityOpt
        sendSyncTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "send_sync")
            , Erlang.OtpErlangString name
            , Erlang.OtpErlangBinary requestInfo
            , Erlang.OtpErlangBinary request
            , Erlang.OtpErlangInteger timeout
            , Erlang.OtpErlangInteger priority]
    in
    case Erlang.termToBinary sendSyncTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right sendSyncBinary -> do
            send api0 sendSyncBinary
            result <- pollRequest api0 (-1) False
            case result of
                Left err ->
                    if err == terminateError && terminateException then
                        Exception.throwIO $ Terminate api0
                    else
                        return $ Left err
                Right (_, api1@Instance.T{
                      Instance.responseInfo = responseInfo
                    , Instance.response = response
                    , Instance.transId = transId}) ->
                    return $ Right (responseInfo, response, transId, api1)

-- | sends asynchronous service requests to all subscribers
-- of the matching service name pattern
mcastAsync :: Typeable s => Instance.T s -> ByteString -> ByteString ->
    Maybe Int -> Maybe ByteString -> Maybe Int ->
    IO (Result (Array Int ByteString, Instance.T s))
mcastAsync api0@Instance.T{
      Instance.terminateException = terminateException
    , Instance.timeoutAsync = timeoutAsync'
    , Instance.priorityDefault = priorityDefault}
    name request timeoutOpt requestInfoOpt priorityOpt =
    let timeout = fromMaybe timeoutAsync' timeoutOpt
        requestInfo = fromMaybe ByteString.empty requestInfoOpt
        priority = fromMaybe priorityDefault priorityOpt
        mcastAsyncTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "mcast_async")
            , Erlang.OtpErlangString name
            , Erlang.OtpErlangBinary requestInfo
            , Erlang.OtpErlangBinary request
            , Erlang.OtpErlangInteger timeout
            , Erlang.OtpErlangInteger priority]
    in
    case Erlang.termToBinary mcastAsyncTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right mcastAsyncBinary -> do
            send api0 mcastAsyncBinary
            result <- pollRequest api0 (-1) False
            case result of
                Left err ->
                    if err == terminateError && terminateException then
                        Exception.throwIO $ Terminate api0
                    else
                        return $ Left err
                Right (_, api1@Instance.T{Instance.transIds = transIds}) ->
                    return $ Right (transIds, api1)

-- | forwards a service request to a different service name
forward_ :: Typeable s =>
    Instance.T s -> Instance.RequestType -> ByteString ->
    ByteString -> ByteString -> Int -> Int -> ByteString -> Source ->
    IO ()
forward_ api0 Instance.ASYNC = forwardAsync api0
forward_ api0 Instance.SYNC = forwardSync api0

forwardAsyncI :: Instance.T s -> ByteString ->
    ByteString -> ByteString -> Int -> Int -> ByteString -> Source ->
    IO (Result (Instance.T s))
forwardAsyncI api0 name responseInfo response timeout priority transId pid = do
    let forwardTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "forward_async")
            , Erlang.OtpErlangString name
            , Erlang.OtpErlangBinary responseInfo
            , Erlang.OtpErlangBinary response
            , Erlang.OtpErlangInteger timeout
            , Erlang.OtpErlangInteger priority
            , Erlang.OtpErlangBinary transId
            , Erlang.OtpErlangPid pid]
    case Erlang.termToBinary forwardTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right forwardBinary -> do
            send api0 forwardBinary
            return $ Right api0

-- | forwards an asynchronous service request to a different service name
forwardAsync :: Typeable s => Instance.T s -> ByteString ->
    ByteString -> ByteString -> Int -> Int -> ByteString -> Source ->
    IO ()
forwardAsync api0 name responseInfo response timeout priority transId pid = do
    result <- forwardAsyncI api0
        name responseInfo response timeout priority transId pid
    case result of
        Left err ->
            error err
        Right api1 ->
            Exception.throwIO $ ForwardAsync api1

forwardSyncI :: Instance.T s -> ByteString ->
    ByteString -> ByteString -> Int -> Int -> ByteString -> Source ->
    IO (Result (Instance.T s))
forwardSyncI api0 name responseInfo response timeout priority transId pid = do
    let forwardTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "forward_sync")
            , Erlang.OtpErlangString name
            , Erlang.OtpErlangBinary responseInfo
            , Erlang.OtpErlangBinary response
            , Erlang.OtpErlangInteger timeout
            , Erlang.OtpErlangInteger priority
            , Erlang.OtpErlangBinary transId
            , Erlang.OtpErlangPid pid]
    case Erlang.termToBinary forwardTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right forwardBinary -> do
            send api0 forwardBinary
            return $ Right api0

-- | forwards a synchronous service request to a different service name
forwardSync :: Typeable s => Instance.T s -> ByteString ->
    ByteString -> ByteString -> Int -> Int -> ByteString -> Source ->
    IO ()
forwardSync api0 name responseInfo response timeout priority transId pid = do
    result <- forwardSyncI api0
        name responseInfo response timeout priority transId pid
    case result of
        Left err ->
            error err
        Right api1 ->
            Exception.throwIO $ ForwardSync api1

-- | provides a response to a service request
return_ :: Typeable s =>
    Instance.T s -> Instance.RequestType -> ByteString -> ByteString ->
    ByteString -> ByteString -> Int -> ByteString -> Source ->
    IO ()
return_ api0 Instance.ASYNC = returnAsync api0
return_ api0 Instance.SYNC = returnSync api0

returnAsyncI :: Instance.T s -> ByteString -> ByteString ->
    ByteString -> ByteString -> Int -> ByteString -> Source ->
    IO (Result (Instance.T s))
returnAsyncI api0 name pattern responseInfo response timeout transId pid = do
    let returnTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "return_async")
            , Erlang.OtpErlangString name
            , Erlang.OtpErlangString pattern
            , Erlang.OtpErlangBinary responseInfo
            , Erlang.OtpErlangBinary response
            , Erlang.OtpErlangInteger timeout
            , Erlang.OtpErlangBinary transId
            , Erlang.OtpErlangPid pid]
    case Erlang.termToBinary returnTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right returnBinary -> do
            send api0 returnBinary
            return $ Right api0

-- | provides a response to an asynchronous service request
returnAsync :: Typeable s => Instance.T s -> ByteString -> ByteString ->
    ByteString -> ByteString -> Int -> ByteString -> Source ->
    IO ()
returnAsync api0 name pattern responseInfo response timeout transId pid = do
    result <- returnAsyncI api0
        name pattern responseInfo response timeout transId pid
    case result of
        Left err ->
            error err
        Right api1 ->
            Exception.throwIO $ ReturnAsync api1

returnSyncI :: Instance.T s -> ByteString -> ByteString ->
    ByteString -> ByteString -> Int -> ByteString -> Source ->
    IO (Result (Instance.T s))
returnSyncI api0 name pattern responseInfo response timeout transId pid = do
    let returnTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "return_sync")
            , Erlang.OtpErlangString name
            , Erlang.OtpErlangString pattern
            , Erlang.OtpErlangBinary responseInfo
            , Erlang.OtpErlangBinary response
            , Erlang.OtpErlangInteger timeout
            , Erlang.OtpErlangBinary transId
            , Erlang.OtpErlangPid pid]
    case Erlang.termToBinary returnTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right returnBinary -> do
            send api0 returnBinary
            return $ Right api0

-- | provides a response to a synchronous service request
returnSync :: Typeable s => Instance.T s -> ByteString -> ByteString ->
    ByteString -> ByteString -> Int -> ByteString -> Source ->
    IO ()
returnSync api0 name pattern responseInfo response timeout transId pid = do
    result <- returnSyncI api0
        name pattern responseInfo response timeout transId pid
    case result of
        Left err ->
            error err
        Right api1 ->
            Exception.throwIO $ ReturnSync api1

-- | blocks to receive an asynchronous service request response
recvAsync :: Typeable s => Instance.T s ->
    Maybe Int -> Maybe ByteString -> Maybe Bool ->
    IO (Result (ByteString, ByteString, ByteString, Instance.T s))
recvAsync api0@Instance.T{
      Instance.terminateException = terminateException
    , Instance.timeoutSync = timeoutSync'}
    timeoutOpt transIdOpt consumeOpt =
    let timeout = fromMaybe timeoutSync' timeoutOpt
        transId = fromMaybe transIdNull transIdOpt
        consume = fromMaybe True consumeOpt
        recvAsyncTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "recv_async")
            , Erlang.OtpErlangInteger timeout
            , Erlang.OtpErlangBinary transId
            , Erlang.OtpErlangAtomBool consume]
    in
    case Erlang.termToBinary recvAsyncTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right recvAsyncBinary -> do
            send api0 recvAsyncBinary
            result <- pollRequest api0 (-1) False
            case result of
                Left err ->
                    if err == terminateError && terminateException then
                        Exception.throwIO $ Terminate api0
                    else
                        return $ Left err
                Right (_, api1@Instance.T{
                      Instance.responseInfo = responseInfo
                    , Instance.response = response
                    , Instance.transId = transId'}) ->
                    return $ Right (responseInfo, response, transId', api1)

-- | returns the 0-based index of this process in the service instance
processIndex :: Instance.T s -> Int
processIndex Instance.T{Instance.processIndex = processIndex'} =
    processIndex'

-- | returns the current process count based on the service configuration
processCount :: Instance.T s -> Int
processCount Instance.T{Instance.processCount = processCount'} =
    processCount'

-- | returns the count_process_dynamic maximum count
-- based on the service configuration
processCountMax :: Instance.T s -> Int
processCountMax Instance.T{Instance.processCountMax = processCountMax'} =
    processCountMax'

-- | returns the count_process_dynamic minimum count
-- based on the service configuration
processCountMin :: Instance.T s -> Int
processCountMin Instance.T{Instance.processCountMin = processCountMin'} =
    processCountMin'

-- | returns the service name pattern prefix from the service configuration
prefix :: Instance.T s -> ByteString
prefix Instance.T{Instance.prefix = prefix'} =
    prefix'

-- | returns the service initialization timeout
-- from the service configuration
timeoutInitialize :: Instance.T s -> Int
timeoutInitialize Instance.T{Instance.timeoutInitialize = timeoutInitialize'} =
    timeoutInitialize'

-- | returns the default asynchronous service request send timeout
-- from the service configuration
timeoutAsync :: Instance.T s -> Int
timeoutAsync Instance.T{Instance.timeoutAsync = timeoutAsync'} =
    timeoutAsync'

-- | returns the default synchronous service request send timeout
-- from the service configuration
timeoutSync :: Instance.T s -> Int
timeoutSync Instance.T{Instance.timeoutSync = timeoutSync'} =
    timeoutSync'

-- | returns the service termination timeout
-- based on the service configuration
timeoutTerminate :: Instance.T s -> Int
timeoutTerminate Instance.T{Instance.timeoutTerminate = timeoutTerminate'} =
    timeoutTerminate'

nullResponse :: RequestType -> ByteString -> ByteString ->
    ByteString -> ByteString -> Int -> Int -> ByteString -> Source ->
    s -> Instance.T s -> IO (Instance.Response s)
nullResponse _ _ _ _ _ _ _ _ _ state api0 =
    return $ Instance.Null (state, api0)

callback :: Typeable s => Instance.T s ->
    (RequestType, ByteString, ByteString, ByteString, ByteString,
     Int, Int, ByteString, Source) -> IO (Result (Instance.T s))
callback api0@Instance.T{
      Instance.state = state
    , Instance.callbacks = callbacks}
    (requestType, name, pattern, requestInfo, request,
     timeout, priority, transId, pid) = do
    let (callbackF, callbacksNew) = case Map.lookup pattern callbacks of
            Nothing ->
                (nullResponse, callbacks)
            Just functionQueue ->
                let f = Sequence.index functionQueue 0
                    functionQueueNew = (Sequence.|>)
                        (Sequence.drop 0 functionQueue) f
                in
                (f, Map.insert pattern functionQueueNew callbacks)
        api1 = api0{Instance.callbacks = callbacksNew}
        empty = ByteString.empty
    callbackResultValue <- Exception.try $ case requestType of
        Instance.ASYNC -> do
            callbackResultAsyncValue <- Exception.try $
                callbackF requestType name pattern
                requestInfo request timeout priority transId pid
                state api1
            case callbackResultAsyncValue of
                Left (Terminate api2) ->
                    return $ ReturnI (empty, empty, state, setTerminate api2)
                Left (ReturnAsync api2) ->
                    return $ Finished api2
                Left (ReturnSync api2) -> do
                    printException "Synchronous Call Return Invalid"
                    return $ Finished (setTerminate api2)
                Left (ForwardAsync api2) ->
                    return $ Finished api2
                Left (ForwardSync api2) -> do
                    printException "Synchronous Call Forward Invalid"
                    return $ Finished (setTerminate api2)
                Right (Instance.ResponseInfo (v0, v1, v2, v3)) ->
                    return $ ReturnI (v0, v1, v2, v3)
                Right (Instance.Response (v0, v1, v2)) ->
                    return $ ReturnI (empty, v0, v1, v2)
                Right (Instance.Forward (v0, v1, v2, v3, v4)) ->
                    return $ ForwardI (v0, v1, v2, timeout, priority, v3, v4)
                Right (Instance.Forward_ (v0, v1, v2, v3, v4, v5, v6)) ->
                    return $ ForwardI (v0, v1, v2, v3, v4, v5, v6)
                Right (Instance.Null (v0, v1)) ->
                    return $ ReturnI (empty, empty, v0, v1)
                Right (Instance.NullError (err, v0, v1)) -> do
                    printError err
                    return $ ReturnI (empty, empty, v0, v1)
        Instance.SYNC -> do
            callbackResultSyncValue <- Exception.try $
                callbackF requestType name pattern
                requestInfo request timeout priority transId pid
                state api1
            case callbackResultSyncValue of
                Left (Terminate api2) ->
                    return $ ReturnI (empty, empty, state, setTerminate api2)
                Left (ReturnSync api2) ->
                    return $ Finished api2
                Left (ReturnAsync api2) -> do
                    printException "Asynchronous Call Return Invalid"
                    return $ Finished (setTerminate api2)
                Left (ForwardSync api2) ->
                    return $ Finished api2
                Left (ForwardAsync api2) -> do
                    printException "Asynchronous Call Forward Invalid"
                    return $ Finished (setTerminate api2)
                Right (Instance.ResponseInfo (v0, v1, v2, v3)) ->
                    return $ ReturnI (v0, v1, v2, v3)
                Right (Instance.Response (v0, v1, v2)) ->
                    return $ ReturnI (empty, v0, v1, v2)
                Right (Instance.Forward (v0, v1, v2, v3, v4)) ->
                    return $ ForwardI (v0, v1, v2, timeout, priority, v3, v4)
                Right (Instance.Forward_ (v0, v1, v2, v3, v4, v5, v6)) ->
                    return $ ForwardI (v0, v1, v2, v3, v4, v5, v6)
                Right (Instance.Null (v0, v1)) ->
                    return $ ReturnI (empty, empty, v0, v1)
                Right (Instance.NullError (err, v0, v1)) -> do
                    printError err
                    return $ ReturnI (empty, empty, v0, v1)
    callbackResultType <- case callbackResultValue of
        Left exception -> do
            printException $ show (exception :: Exception.SomeException)
            return $ ReturnI (empty, empty, state, api1)
        Right callbackResult ->
            return $ callbackResult
    case requestType of
        Instance.ASYNC ->
            case callbackResultType of
                Finished api3 ->
                    return $ Right api3
                ReturnI (responseInfo, response, state', api3) ->
                    returnAsyncI api3{Instance.state = state'}
                        name pattern responseInfo response timeout transId pid
                ForwardI (name', requestInfo', request', timeout', priority',
                          state', api3) ->
                    forwardAsyncI api3{Instance.state = state'}
                        name' requestInfo' request'
                        timeout' priority' transId pid
        Instance.SYNC ->
            case callbackResultType of
                Finished api3 ->
                    return $ Right api3
                ReturnI (responseInfo, response, state', api3) ->
                    returnSyncI api3{Instance.state = state'}
                        name pattern responseInfo response timeout transId pid
                ForwardI (name', requestInfo', request', timeout', priority',
                          state', api3) ->
                    forwardSyncI api3{Instance.state = state'}
                        name' requestInfo' request'
                        timeout' priority' transId pid

handleEvents :: [Message] -> Instance.T s -> Bool -> Word32 ->
    Get ([Message], Instance.T s)
handleEvents messages api0 external cmd0 = do
    cmd <- if cmd0 == 0 then Get.getWord32host else return cmd0
    case () of
      _ | cmd == messageTerm ->
            if external then
                return ([], setTerminate api0)
            else
                fail terminateError
        | cmd == messageReinit -> do
            processCount' <- Get.getWord32host
            timeoutAsync' <- Get.getWord32host
            timeoutSync' <- Get.getWord32host
            priorityDefault <- Get.getInt8
            let api1 = Instance.reinit api0
                    processCount'
                    timeoutAsync'
                    timeoutSync'
                    priorityDefault
            empty <- Get.isEmpty
            if not empty then
                handleEvents messages api1 external 0
            else
                return (messages, api1)
        | cmd == messageKeepalive -> do
            let messagesNew = MessageKeepalive:messages
            empty <- Get.isEmpty
            if not empty then
                handleEvents messagesNew api0 external 0
            else
                return (messagesNew, api0)
        | otherwise ->
            fail messageDecodingError

pollRequestDataGet :: [Message] -> Instance.T s -> Bool ->
    Get ([Message], Instance.T s)
pollRequestDataGet messages api0 external = do
    cmd <- Get.getWord32host
    case () of
      _ | cmd == messageInit -> do
            processIndex' <- Get.getWord32host
            processCount' <- Get.getWord32host
            processCountMax' <- Get.getWord32host
            processCountMin' <- Get.getWord32host
            prefixSize <- Get.getWord32host
            prefix' <- Get.getByteString $ fromIntegral prefixSize - 1
            Get.skip 1
            timeoutInitialize' <- Get.getWord32host
            timeoutAsync' <- Get.getWord32host
            timeoutSync' <- Get.getWord32host
            timeoutTerminate' <- Get.getWord32host
            priorityDefault <- Get.getInt8
            let api1 = Instance.init api0
                    processIndex'
                    processCount'
                    processCountMax'
                    processCountMin'
                    prefix'
                    timeoutInitialize'
                    timeoutAsync'
                    timeoutSync'
                    timeoutTerminate'
                    priorityDefault
            empty <- Get.isEmpty
            if not empty then
                handleEvents messages api1 external 0
            else
                return (messages, api1)
        | cmd == messageSendAsync || cmd == messageSendSync -> do
            nameSize <- Get.getWord32host
            name <- Get.getByteString $ fromIntegral nameSize - 1
            Get.skip 1
            patternSize <- Get.getWord32host
            pattern <- Get.getByteString $ fromIntegral patternSize - 1
            Get.skip 1
            requestInfoSize <- Get.getWord32host
            requestInfo <- Get.getByteString $ fromIntegral requestInfoSize
            Get.skip 1
            requestSize <- Get.getWord32host
            request <- Get.getByteString $ fromIntegral requestSize
            Get.skip 1
            timeout <- Get.getWord32host
            priority <- Get.getInt8
            transId <- Get.getByteString 16
            pidSize <- Get.getWord32host
            pidData <- Get.getLazyByteString $ fromIntegral pidSize
            empty <- Get.isEmpty
            case Erlang.binaryToTerm pidData of
                Left err ->
                    fail $ show err
                Right (Erlang.OtpErlangPid (pid)) ->
                    let requestType =
                            if cmd == messageSendAsync then
                                Instance.ASYNC
                            else -- cmd == messageSendSync
                                Instance.SYNC
                        messagesNew = (MessageSend (
                            requestType, name, pattern, requestInfo, request,
                            fromIntegral timeout, fromIntegral priority,
                            transId, pid)):messages in
                    if not empty then
                        handleEvents messagesNew api0 external 0
                    else
                        return (messagesNew, api0)
                Right _ ->
                    fail messageDecodingError
        | cmd == messageRecvAsync || cmd == messageReturnSync -> do
            responseInfoSize <- Get.getWord32host
            responseInfo <- Get.getByteString $ fromIntegral responseInfoSize
            Get.skip 1
            responseSize <- Get.getWord32host
            response <- Get.getByteString $ fromIntegral responseSize
            Get.skip 1
            transId <- Get.getByteString 16
            empty <- Get.isEmpty
            let api1 = Instance.setResponse api0
                    responseInfo response transId
            if not empty then
                handleEvents messages api1 external 0
            else
                return (messages, api1)
        | cmd == messageReturnAsync -> do
            transId <- Get.getByteString 16
            empty <- Get.isEmpty
            let api1 = Instance.setTransId api0
                    transId
            if not empty then
                handleEvents messages api1 external 0
            else
                return (messages, api1)
        | cmd == messageReturnsAsync -> do
            transIdCount <- Get.getWord32host
            transIds <- Get.getByteString $ 16 * (fromIntegral transIdCount)
            empty <- Get.isEmpty
            let api1 = Instance.setTransIds api0
                    transIds transIdCount
            if not empty then
                handleEvents messages api1 external 0
            else
                return (messages, api1)
        | cmd == messageSubscribeCount -> do
            subscribeCount' <- Get.getWord32host
            empty <- Get.isEmpty
            let api1 = Instance.setSubscribeCount api0
                    subscribeCount'
            if not empty then
                handleEvents messages api1 external 0
            else
                return (messages, api1)
        | cmd == messageTerm ->
            handleEvents messages api0 external cmd
        | cmd == messageReinit -> do
            processCount' <- Get.getWord32host
            timeoutAsync' <- Get.getWord32host
            timeoutSync' <- Get.getWord32host
            priorityDefault <- Get.getInt8
            let api1 = Instance.reinit api0
                    processCount'
                    timeoutAsync'
                    timeoutSync'
                    priorityDefault
            empty <- Get.isEmpty
            if not empty then
                pollRequestDataGet messages api1 external
            else
                return (messages, api1)
        | cmd == messageKeepalive -> do
            let messagesNew = MessageKeepalive:messages
            empty <- Get.isEmpty
            if not empty then
                pollRequestDataGet messagesNew api0 external
            else
                return (messagesNew, api0)
        | otherwise ->
            fail messageDecodingError

pollRequestDataProcess :: Typeable s => [Message] -> Instance.T s ->
    IO (Result (Instance.T s))
pollRequestDataProcess [] api0 =
    return $ Right api0
pollRequestDataProcess (message:messages) api0 =
    case message of
        MessageSend callbackData -> do
            callbackResult <- callback api0 callbackData
            case callbackResult of
                Left err ->
                    return $ Left err
                Right api1 ->
                    pollRequestDataProcess messages api1
        MessageKeepalive ->
            let aliveTerms = Erlang.OtpErlangAtom (Char8.pack "keepalive") in
            case Erlang.termToBinary aliveTerms (-1) of
                Left err ->
                    return $ Left $ show err
                Right aliveBinary -> do
                    send api0 aliveBinary
                    pollRequestDataProcess messages api0

pollRequestData :: Typeable s => Instance.T s -> Bool -> LazyByteString ->
    IO (Result (Instance.T s))
pollRequestData api0 external dataIn =
    case Get.runGetOrFail (pollRequestDataGet [] api0 external) dataIn of
        Left (_, _, err) ->
            return $ Left err
        Right (_, _, (messages, api1)) ->
            pollRequestDataProcess (List.reverse messages) api1

pollRequestLoop :: Typeable s =>
    Instance.T s -> Int -> Bool -> Clock.NominalDiffTime ->
    IO (Result (Bool, Instance.T s))
pollRequestLoop api0 timeout external pollTimer = do
    inputAvailable <- pollWait api0 timeout
    if inputAvailable == Just False then
        return $ Right (True, api0{Instance.timeout = Nothing})
    else if inputAvailable == Nothing then
        let api1 = api0{
              Instance.terminate = True
            , Instance.timeout = Nothing} in
        return $ Right (False, api1)
    else do
        (dataIn, _, api1) <- recv api0
        dataResult <- pollRequestData api1 external dataIn
        case dataResult of
            Left err ->
                return $ Left err
            Right api2@Instance.T{Instance.timeout = Just result} ->
                return $ Right (result, api2{Instance.timeout = Nothing})
            Right api2 -> do
                (pollTimerNew, timeoutNew) <- if timeout <= 0 then
                        return (0, timeout)
                    else
                        timeoutAdjustmentPoll pollTimer timeout
                if timeout == 0 then
                    return $ Right (True, api2{Instance.timeout = Nothing})
                else
                    pollRequestLoop api2 timeoutNew external pollTimerNew

pollRequestLoopBegin :: Typeable s =>
    Instance.T s -> Int -> Bool -> Clock.NominalDiffTime ->
    IO (Result (Bool, Instance.T s))
pollRequestLoopBegin api0 timeout external pollTimer = do
    result <- Exception.try (pollRequestLoop api0 timeout external pollTimer)
    case result of
        Left exception ->
            return $ Left $ show (exception :: SomeException)
        Right success ->
            return success

pollRequest :: Typeable s => Instance.T s -> Int -> Bool ->
    IO (Result (Bool, Instance.T s))
pollRequest api0@Instance.T{
      Instance.initializationComplete = initializationComplete
    , Instance.terminate = terminate} timeout external =
    if terminate then
        if external then
            return $ Right (False, api0)
        else
            return $ Left terminateError
    else do
        pollTimer <- if timeout <= 0 then
                return 0
            else
                POSIX.getPOSIXTime
        if external && not initializationComplete then
            let pollingTerms = Erlang.OtpErlangAtom (Char8.pack "polling") in
            case Erlang.termToBinary pollingTerms (-1) of
                Left err ->
                    return $ Left $ show err
                Right pollingBinary -> do
                    send api0 pollingBinary
                    pollRequestLoopBegin
                        api0{Instance.initializationComplete = True}
                        timeout external pollTimer
        else
            pollRequestLoopBegin api0 timeout external pollTimer

pollWait :: Typeable s => Instance.T s -> Int -> IO (Maybe Bool)
pollWait Instance.T{
      Instance.socketHandle = socketHandle
    , Instance.bufferRecvSize = bufferRecvSize}
    timeout = do
    if bufferRecvSize > 0 then
        return $ Just True
    else
        SysIOErr.catchIOError
            (do
             inputAvailable <- SysIO.hWaitForInput socketHandle timeout
             return $ Just inputAvailable)
            (\e -> if SysIOErr.isEOFError e then
                 return Nothing
             else
                 SysIOErr.ioError e)

-- | blocks to process incoming CloudI service requests
poll :: Typeable s => Instance.T s -> Int -> IO (Result (Bool, Instance.T s))
poll api0 timeout =
    pollRequest api0 timeout True

-- | shutdown the service successfully
shutdown :: Instance.T s -> Maybe ByteString ->
    IO (Result (Instance.T s))
shutdown api0 reasonOpt =
    let reason = fromMaybe Char8.empty reasonOpt
        shutdownTerms = Erlang.OtpErlangTuple
            [ Erlang.OtpErlangAtom (Char8.pack "shutdown")
            , Erlang.OtpErlangString reason]
    in
    case Erlang.termToBinary shutdownTerms (-1) of
        Left err ->
            return $ Left $ show err
        Right shutdownBinary -> do
            send api0 shutdownBinary
            return $ Right $ api0

send :: Instance.T s -> LazyByteString -> IO ()
send Instance.T{
      Instance.useHeader = True
    , Instance.socketHandle = socketHandle} binary = do
    let total = fromIntegral (LazyByteString.length binary) :: Word32
    LazyByteString.hPut socketHandle (Builder.toLazyByteString $
        Builder.word32BE total `Monoid.mappend`
        Builder.lazyByteString binary)
send Instance.T{
      Instance.useHeader = False
    , Instance.socketHandle = socketHandle} binary = do
    LazyByteString.hPut socketHandle binary

recvBuffer :: Builder -> Int -> Int -> Handle -> Int ->
    IO (Builder, Int)
recvBuffer bufferRecv bufferRecvSize recvSize socketHandle bufferSize
    | recvSize <= bufferRecvSize =
        return (bufferRecv, bufferRecvSize)
    | otherwise = do
        fragment <- ByteString.hGetNonBlocking socketHandle bufferSize
        recvBuffer
            (bufferRecv `Monoid.mappend` Builder.byteString fragment)
            (bufferRecvSize + ByteString.length fragment)
            recvSize socketHandle bufferSize

recvBufferAll :: Builder -> Int -> Handle -> Int ->
    IO (Builder, Int)
recvBufferAll bufferRecv bufferRecvSize socketHandle bufferSize = do
    fragment <- ByteString.hGetNonBlocking socketHandle bufferSize
    let fragmentSize = ByteString.length fragment
        bufferRecvNew = bufferRecv `Monoid.mappend` Builder.byteString fragment
        bufferRecvSizeNew = bufferRecvSize + fragmentSize
    if fragmentSize == bufferSize then
        recvBufferAll bufferRecvNew bufferRecvSizeNew socketHandle bufferSize
    else
        return (bufferRecv, bufferRecvSize)

recv :: Instance.T s -> IO (LazyByteString, Int, Instance.T s)
recv api0@Instance.T{
      Instance.useHeader = True
    , Instance.socketHandle = socketHandle
    , Instance.bufferSize = bufferSize
    , Instance.bufferRecv = bufferRecv
    , Instance.bufferRecvSize = bufferRecvSize} = do
    (bufferRecvHeader, bufferRecvHeaderSize) <- recvBuffer
        bufferRecv bufferRecvSize 4 socketHandle bufferSize
    let header0 = Builder.toLazyByteString bufferRecvHeader
        Just (byte0, header1) = LazyByteString.uncons header0
        Just (byte1, header2) = LazyByteString.uncons header1
        Just (byte2, header3) = LazyByteString.uncons header2
        Just (byte3, headerRemaining) = LazyByteString.uncons header3
        total = fromIntegral $
            (fromIntegral byte0 :: Word32) `shiftL` 24 .|.
            (fromIntegral byte1 :: Word32) `shiftL` 16 .|.
            (fromIntegral byte2 :: Word32) `shiftL` 8 .|.
            (fromIntegral byte3 :: Word32) :: Int
    (bufferRecvAll, bufferRecvAllSize) <- recvBuffer
        (Builder.lazyByteString headerRemaining)
        (bufferRecvHeaderSize - 4) total socketHandle bufferSize
    let bufferRecvAllStr = Builder.toLazyByteString bufferRecvAll
        (bufferRecvData, bufferRecvNew) =
            LazyByteString.splitAt (fromIntegral total) bufferRecvAllStr
    return $ (
          bufferRecvData
        , total
        , api0{
              Instance.bufferRecv = Builder.lazyByteString bufferRecvNew
            , Instance.bufferRecvSize = bufferRecvAllSize - total})
recv api0@Instance.T{
      Instance.useHeader = False
    , Instance.socketHandle = socketHandle
    , Instance.bufferSize = bufferSize
    , Instance.bufferRecv = bufferRecv
    , Instance.bufferRecvSize = bufferRecvSize} = do
    (bufferRecvAll,
     bufferRecvAllSize) <- recvBufferAll
        bufferRecv bufferRecvSize socketHandle bufferSize
    return $ (
          Builder.toLazyByteString bufferRecvAll
        , bufferRecvAllSize
        , api0{
              Instance.bufferRecv = Monoid.mempty
            , Instance.bufferRecvSize = 0})

timeoutAdjustmentPoll :: Clock.NominalDiffTime -> Int ->
    IO (Clock.NominalDiffTime, Int)
timeoutAdjustmentPoll t0 timeout = do
    t1 <- POSIX.getPOSIXTime
    if t1 <= t0 then
        return (t1, timeout)
    else
        let elapsed = floor ((t1 - t0) * 1000) :: Integer
            timeoutValue = fromIntegral timeout :: Integer in
        if elapsed >= timeoutValue then
            return (t1, 0)
        else
            return (t1, fromIntegral $ timeoutValue - elapsed)

setTerminate :: Instance.T s -> Instance.T s
setTerminate api0 =
    api0{ Instance.terminate = True
        , Instance.timeout = Just False}

threadList :: Concurrent.MVar [Concurrent.MVar ()]
threadList = Unsafe.unsafePerformIO (Concurrent.newMVar [])

-- | simplifies thread creation and join
--
-- > Concurrent.setNumCapabilities threadCount
-- > mapM_ (CloudI.threadCreate task) [0..threadCount - 1]
-- > CloudI.threadsWait
threadCreate :: (Int -> IO ()) -> Int -> IO ThreadId
threadCreate f threadIndex = do
    thread <- Concurrent.newEmptyMVar
    threads <- Concurrent.takeMVar threadList
    Concurrent.putMVar threadList (thread:threads)
    threadCreateFork threadIndex (f threadIndex)
        (\_ -> Concurrent.putMVar thread ())

threadCreateFork :: Int -> IO a -> (Either SomeException a -> IO ()) ->
    IO ThreadId
threadCreateFork threadIndex action afterF =
    -- similar to Concurrent.forkFinally
    Exception.mask $ \restore ->
        Concurrent.forkOn threadIndex
            (Exception.try (restore action) >>= afterF)

-- | wait for threads to join after being created by 'threadCreate'
threadsWait :: IO ()
threadsWait = do
    threads <- Concurrent.takeMVar threadList
    case threads of
        [] ->
            return ()
        done:remaining -> do
            Concurrent.putMVar threadList remaining
            Concurrent.takeMVar done
            threadsWait

textPairsParse :: ByteString -> Map ByteString [ByteString]
textPairsParse text =
    let loop m [] = m
        loop m [v] =
            if v == ByteString.empty then
                m
            else
                error "not text_pairs"
        loop m (k:(v:l')) =
            case Map.lookup k m of
                Nothing ->
                    loop (Map.insert k [v] m) l'
                Just v' ->
                    loop (Map.insert k (v' ++ [v]) m) l'
    in
    loop Map.empty (Char8.split '\0' text)

textPairsNew :: Map ByteString [ByteString] -> Maybe Bool -> ByteString
textPairsNew pairs responseOpt =
    let response = fromMaybe True responseOpt in
    if response && Map.size pairs == 0 then
        Char8.pack "\0"
    else
        let pair builder _ [] =
                builder
            pair builder k (v:l') =
                pair (builder <>
                    Builder.byteString k <> Builder.char8 '\0' <>
                    Builder.byteString v <> Builder.char8 '\0') k l'
        in
        LazyByteString.toStrict $ Builder.toLazyByteString $
            Map.foldlWithKey pair Monoid.mempty pairs

-- | decode service request info key/value data
infoKeyValueParse :: ByteString -> Map ByteString [ByteString]
infoKeyValueParse = textPairsParse

-- | encode service response info key/value data
infoKeyValueNew :: Map ByteString [ByteString] -> Maybe Bool -> ByteString
infoKeyValueNew = textPairsNew