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{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
import Control.Monad (when, void, forever)
import UnliftIO (try, IOException) -- liftIO
import UnliftIO.MVar
import UnliftIO.Chan
import UnliftIO.Concurrent (forkIO, killThread)
import qualified Data.Text as T
import qualified Data.Text.IO as TIO
import Discord
import Discord.Types
import qualified Discord.Requests as R
import ExampleUtils (getToken)
main :: IO ()
main = stateExample
data State = State { pingCount :: Integer }
deriving (Show, Read, Eq, Ord)
-- | Counts how many pings we've seen across sessions
stateExample :: IO ()
stateExample = do
tok <- getToken
-- eventHandler is called concurrently, need to sync stdout
printQueue <- newChan :: IO (Chan T.Text)
threadId <- forkIO $ forever $ readChan printQueue >>= TIO.putStrLn
-- try to read previous state, otherwise use 0
state :: MVar (State) <- do
mfile <- try $ read . T.unpack <$> TIO.readFile "./cachedState"
s <- case mfile of
Right file -> do
writeChan printQueue "loaded state from file"
pure file
Left (_ :: IOException) -> do
writeChan printQueue "created new state"
pure $ State { pingCount = 0 }
newMVar s
t <- runDiscord $ def { discordToken = tok
, discordOnStart = writeChan printQueue "starting ping loop"
, discordOnEvent = eventHandler state printQueue
, discordOnEnd = do killThread threadId
--
s <- readMVar state
TIO.writeFile "./cachedState" (T.pack (show s))
}
TIO.putStrLn t
eventHandler :: MVar State -> Chan T.Text -> Event -> DiscordHandler ()
eventHandler state printQueue event = case event of
-- respond to message, and modify state
MessageCreate m -> when (not (fromBot m) && isPing m) $ do
writeChan printQueue "got a ping!"
s <- takeMVar state
void $ restCall (R.CreateMessage (messageChannelId m) (T.pack ("Pong #" <> show (pingCount s))))
putMVar state $ State { pingCount = pingCount s + 1 }
_ -> pure ()
fromBot :: Message -> Bool
fromBot = userIsBot . messageAuthor
isPing :: Message -> Bool
isPing = ("ping" `T.isPrefixOf`) . T.toLower . messageContent
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