{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE OverloadedRecordDot #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeFamilies #-}

module Hsm.Core.Zmq.Client
  ( Client
  , receive
  , poll
  , runClient
  ) where

import Control.Monad (forM_)
import Control.Monad.Loops (whileM)
import Data.Binary (Binary)
import Data.Text (Text, pack, unpack)
import Data.Text.Encoding (encodeUtf8)
import Effectful (Dispatch(Static), DispatchOf, Eff, IOE, (:>))
import Effectful.Dispatch.Static qualified as E
import Effectful.Log (Log, localDomain, logInfo_, logTrace_)
import Effectful.Reader.Static (Reader, ask)
import Effectful.Resource (Resource)
import GHC.Records (HasField)
import Hsm.Core.Message (body, topic)
import Hsm.Core.Zmq (withSocket)
import Streamly.Data.Stream (Stream, repeatM)
import System.ZMQ4 qualified as Z

data Client a b

type instance DispatchOf Client = Static E.WithSideEffects

newtype instance E.StaticRep Client =
  Client (Z.Socket Z.Sub)

domain :: Text
domain = "client"

receiver ::
     forall es a. (Log :> es, Client :> es, Binary a, Show a)
  => Eff es a
receiver = do
  Client sock <- E.getStaticRep
  message <- E.unsafeEff_ $ Z.receive sock
  localDomain domain
    $ logTrace_
    $ "Message received ["
        <> topic message
        <> "]: "
        <> pack (show $ body @a message)
  return $ body message

receive :: (Log :> es, Client :> es, Binary a, Show a) => Stream (Eff es) a
receive = repeatM receiver

poll :: (Log :> es, Client :> es, Binary a, Show a) => Stream (Eff es) [a]
poll =
  repeatM $ do
    ms <- whileM newMsg receiver
    localDomain domain
      $ localDomain "poller"
      $ logTrace_
      $ pack (show $ length ms) <> " new message(s) on queue"
    return ms
  where
    newMsg = do
      Client sock <- E.getStaticRep
      peek <- E.unsafeEff_ $ Z.poll 0 [Z.Sock sock [Z.In] Nothing]
      return $ peek /= [[]]

runClient ::
     forall env es a.
     ( HasField "subEps" env [Text]
     , HasField "topics" env [Text]
     , IOE :> es
     , Log :> es
     , Reader env :> es
     , Resource :> es
     )
  => Eff (Client : es) a
  -> Eff es a
runClient action =
  withSocket Z.Sub >>= \sock ->
    E.evalStaticRep (Client sock) $ do
      localDomain domain $ do
        logInfo_ "Initializing ZMQ client"
        env <- ask @env
        forM_ env.subEps $ E.unsafeEff_ . Z.connect sock . unpack
        forM_ env.topics $ E.unsafeEff_ . Z.subscribe sock . encodeUtf8
        logTrace_ $ "Listening to " <> pack (show env.subEps)
        logTrace_ $ "Subscribed to " <> pack (show env.topics)
      action