1 files changed, 108 insertions, 0 deletions
diff --git a/hsm-core/Hsm/Core/Zmq/Client.hs b/hsm-core/Hsm/Core/Zmq/Client.hs
new file mode 100644
index 0000000..793841e
--- /dev/null
+++ b/hsm-core/Hsm/Core/Zmq/Client.hs
@@ -0,0 +1,108 @@
+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE OverloadedRecordDot #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeFamilies #-}
+
+module Hsm.Core.Zmq.Client
+  ( Client
+  , receive
+  , poll
+  , runClient
+  ) where
+
+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 ::
+     forall es a. (Log :> es, Client :> es, Binary a, Show a)
+  => Stream (Eff es) a
+receive = repeatM receiver
+
+poll ::
+     forall es a. (Log :> es, Client :> es, Binary a, Show a)
+  => Stream (Eff es) [a]
+poll = repeatM poller
+  where
+    newMsg :: Eff es Bool
+    newMsg = do
+      Client sock <- E.getStaticRep
+      peek <- E.unsafeEff_ $ Z.poll 0 [Z.Sock sock [Z.In] Nothing]
+      return $ peek /= [[]]
+    --
+    poller :: Eff es [a]
+    poller = do
+      ms <- whileM newMsg receiver
+      localDomain domain
+        $ localDomain "poller"
+        $ logTrace_
+        $ pack (show $ length ms) <> " new message(s) on queue"
+      return ms
+
+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 >>= run
+  where
+    run :: Z.Socket Z.Sub -> Eff es a
+    run sock = E.evalStaticRep (Client sock) $ initialize >> action
+      where
+        connect :: Text -> Eff (Client : es) ()
+        connect = E.unsafeEff_ . Z.connect sock . unpack
+        --
+        subscribe :: Text -> Eff (Client : es) ()
+        subscribe = E.unsafeEff_ . Z.subscribe sock . encodeUtf8
+        --
+        initialize :: Eff (Client : es) ()
+        initialize =
+          localDomain domain $ do
+            logInfo_ "Initializing ZMQ client"
+            env <- ask @env
+            mapM_ connect env.subEps
+            mapM_ subscribe env.topics
+            logTrace_ $ "Listening to " <> pack (show env.subEps)
+            logTrace_ $ "Subscribed to " <> pack (show env.topics)