{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE DeriveGeneric #-}
module Main where

import Control.Monad.Catch (SomeException)
import Data.Aeson (FromJSON, ToJSON)
import Data.Text (Text)
import GHC.Generics (Generic)
import qualified Network.AMQP.Worker as Worker
import Network.AMQP.Worker (fromURI, Exchange, Queue, Direct, def, WorkerException, Message(..), Connection)
import System.IO (hSetBuffering, stdout, stderr, BufferMode(..))

data TestMessage = TestMessage
  { greeting :: Text }
  deriving (Generic, Show, Eq)

instance FromJSON TestMessage
instance ToJSON TestMessage


exchange :: Exchange
exchange = Worker.exchange "testExchange"


queue :: Queue Direct TestMessage
queue = Worker.queue exchange "testQueue"


results :: Queue Direct Text
results = Worker.queue exchange "resultQueue"


example :: IO ()
example = do
  -- connect
  conn <- Worker.connect (fromURI "amqp://guest:guest@localhost:5672")

  -- initialize the queues
  Worker.initQueue conn queue
  Worker.initQueue conn results

  -- publish a message
  Worker.publish conn queue (TestMessage "hello world")

  -- create a worker, the program loops here
  Worker.worker def conn queue onError (onMessage conn)


onMessage :: Connection -> Message TestMessage -> IO ()
onMessage conn m = do
  let testMessage = value m
  putStrLn "Got Message"
  print testMessage
  Worker.publish conn results (greeting testMessage)


onError :: WorkerException SomeException -> IO ()
onError e = do
  putStrLn "Do something with errors"
  print e



main :: IO ()
main = do
  hSetBuffering stdout LineBuffering
  hSetBuffering stderr LineBuffering
  example