Listen for messages

reddit_tags/reddit-tags.cabal

@@ -34,6 +34,7 @@ library
                     , aeson
                     , lens
                     , lens-aeson
+                    , transformers
     hs-source-dirs:   src
     default-language: Haskell2010
 

reddit_tags/src/MyLib.hs

@@ -1,4 +1,39 @@
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE OverloadedStrings #-}
 module MyLib (someFunc) where
+import System.Environment (lookupEnv)
+import Control.Monad.Trans.Maybe (MaybeT(..))
+import Network.AMQP
+import qualified Data.Text as T
+import Data.Text (Text)
+import Control.Exception (bracket)
+import Control.Concurrent (newEmptyMVar, readMVar)
+import Control.Monad (void)
+
+data AMQP = AMQP
+  { host :: String
+  , vhost :: Text
+  , username :: Text
+  , password :: Text
+  }
+
+getAMQP :: IO (Maybe AMQP)
+getAMQP = runMaybeT $
+  AMQP <$> lookupEnvM "AMQP_HOST" <*> lookupEnvMText "AMQP_VHOST" <*> lookupEnvMText "AMQP_USER" <*> lookupEnvMText "AMQP_PASS"
+  where
+    lookupEnvM = MaybeT . lookupEnv
+    lookupEnvMText = fmap T.pack . lookupEnvM
 
 someFunc :: IO ()
-someFunc = putStrLn "someFunc"
+someFunc = do
+  Just AMQP{..} <- getAMQP
+  let rabbitConnect = openConnection host vhost username password
+  bracket rabbitConnect closeConnection $ \conn -> do
+    chan <- openChannel conn
+    qos chan 0 1 False
+    declareQueue chan newQueue {queueName="reddit_tags"}
+    bindQueue chan "reddit_tags" "reddit_posts" "key"
+    consumeMsgs chan "reddit_tags" Ack $ \(msg, env) -> do
+      print msg
+      ackEnv env
+    void getLine