Client.hs

{-# OPTIONS_GHC -Wno-name-shadowing #-}

-- | The client
module Calamity.Client.Client (
  react,
  runBotIO,
  runBotIO',
  stopBot,
  sendPresence,
  events,
  fire,
  waitUntil,
  waitUntilM,
  CalamityEvent (Dispatch, ShutDown),
  customEvt,
) where

import Calamity.Cache.Eff
import Calamity.Client.ShardManager
import Calamity.Client.Types
import Calamity.Gateway.DispatchEvents
import Calamity.Gateway.Intents
import Calamity.Gateway.Types
import Calamity.HTTP.Internal.Ratelimit
import Calamity.Internal.ConstructorName
import Calamity.Internal.RunIntoIO
import qualified Calamity.Internal.SnowflakeMap as SM
import Calamity.Internal.UnixTimestamp
import Calamity.Internal.Updateable
import Calamity.Internal.Utils
import Calamity.Metrics.Eff
import Calamity.Types.LogEff
import Calamity.Types.Model.Channel
import Calamity.Types.Model.Guild
import Calamity.Types.Model.Presence (Presence (..))
import Calamity.Types.Model.User
import qualified Calamity.Types.Model.Voice as V
import Calamity.Types.Snowflake
import Calamity.Types.Token
import Control.Concurrent.Chan.Unagi
import Control.Concurrent.MVar
import Control.Concurrent.STM
import Control.Exception (SomeException)
import Control.Lens hiding ((<.>))
import Control.Monad
import Data.Default.Class
import Data.Dynamic
import Data.Foldable
import Data.Generics.Product.Subtype
import Data.IORef
import Data.Maybe
import Data.Proxy
import qualified Data.Text as S
import Data.Time.Clock.POSIX
import qualified Df1
import qualified Di.Core as DC
import qualified DiPolysemy as Di
import qualified Polysemy as P
import qualified Polysemy.Async as P
import qualified Polysemy.AtomicState as P
import qualified Polysemy.Error as P
import qualified Polysemy.Fail as P
import qualified Polysemy.Reader as P
import qualified Polysemy.Resource as P
import PyF
import TextShow (TextShow (showt))

timeA :: P.Member (P.Embed IO) r => P.Sem r a -> P.Sem r (Double, a)
timeA m = do
  start <- P.embed getPOSIXTime
  res <- m
  end <- P.embed getPOSIXTime
  let duration = fromRational . toRational $ end - start
  pure (duration, res)


newClient :: Token -> Maybe (DC.Di Df1.Level Df1.Path Df1.Message) -> IO Client
newClient token initialDi = do
  shards'        <- newTVarIO []
  numShards'     <- newEmptyMVar
  rlState'       <- newRateLimitState
  (inc, outc)    <- newChan
  ehidCounter    <- newIORef 0

  pure $ Client shards'
                numShards'
                token
                rlState'
                inc
                outc
                ehidCounter
                initialDi

-- | Create a bot, run your setup action, and then loop until the bot closes.
runBotIO :: forall r a.
         (P.Members '[P.Embed IO, P.Final IO, CacheEff, MetricEff, LogEff] r, Typeable (SetupEff r))
         => Token
         -> Intents
         -- ^ The intents the bot should use
         -> P.Sem (SetupEff r) a
         -> P.Sem r (Maybe StartupError)
runBotIO token intents = runBotIO' token intents Nothing

resetDi :: BotC r => P.Sem r a -> P.Sem r a
resetDi m = do
  initialDi <- P.asks (^. #initialDi)
  Di.local (flip fromMaybe initialDi) m

-- | Create a bot, run your setup action, and then loop until the bot closes.
--
-- This version allows you to specify the initial status, and intents.
runBotIO' :: forall r a.
          (P.Members '[P.Embed IO, P.Final IO, CacheEff, MetricEff, LogEff] r, Typeable (SetupEff r))
          => Token
          -> Intents
          -- ^ The intents the bot should use
          -> Maybe StatusUpdateData
          -- ^ The initial status to send to the gateway
          -> P.Sem (SetupEff r) a
          -> P.Sem r (Maybe StartupError)
runBotIO' token intents status setup = do
  initialDi <- Di.fetch
  client <- P.embed $ newClient token initialDi
  handlers <- P.embed $ newTVarIO def
  P.asyncToIOFinal . P.runAtomicStateTVar handlers . P.runReader client . Di.push "calamity" $ do
    void $ Di.push "calamity-setup" setup
    r <- shardBot status intents
    case r of
      Left e  -> pure (Just e)
      Right _ -> do
        Di.push "calamity-loop" clientLoop
        Di.push "calamity-stop" finishUp
        pure Nothing

-- | Register an event handler, returning an action that removes the event handler from the bot.
--
-- Refer to 'EventType' for what events you can register, and 'EHType' for the
-- parameters the event handlers they receive.
--
-- You'll probably want @TypeApplications@ and need @DataKinds@ enabled to
-- specify the type of @s@.
--
-- ==== Examples
--
-- Reacting to every message:
--
-- @
-- 'react' @\''MessageCreateEvt' '$' \msg -> 'print' '$' "Got message: " '<>' 'show' msg
-- @
--
-- Reacting to a custom event:
--
-- @
-- data MyCustomEvt = MyCustomEvt 'Data.Text.Text' 'Message'
--
-- 'react' @(\''CustomEvt' MyCustomEvt) $ \\(MyCustomEvt s m) ->
--    'void' $ 'Calamity.Types.Tellable.tell' @'Data.Text.Text' m ("Somebody told me to tell you about: " '<>' s)
-- @
--
-- ==== Notes
--
-- This function is pretty bad for giving nasty type errors,
-- since if something doesn't match then 'EHType' might not get substituted,
-- which will result in errors about parameter counts mismatching.
react :: forall (s :: EventType) r.
      (BotC r, ReactConstraints s)
      => (EHType s -> (P.Sem r) ())
      -> P.Sem r (P.Sem r ())
react handler = do
  handler' <- bindSemToIO handler
  ehidC <- P.asks (^. #ehidCounter)
  id' <- P.embed $ atomicModifyIORef ehidC (\i -> (i + 1, i))
  let handlers = makeEventHandlers (Proxy @s) id' (const () <.> handler')
  P.atomicModify (handlers <>)
  pure $ removeHandler @s id'

removeHandler :: forall (s :: EventType) r. (BotC r, RemoveEventHandler s) => Integer -> P.Sem r ()
removeHandler id' = P.atomicModify (removeEventHandler (Proxy @s) id')

-- | Fire an event that the bot will then handle.
--
-- ==== Examples
--
-- Firing an event named \"my-event\":
--
-- @
-- 'fire' '$' 'customEvt' @"my-event" ("aha" :: 'Data.Text.Text', msg)
-- @
fire :: BotC r => CalamityEvent -> P.Sem r ()
fire e = do
  inc <- P.asks (^. #eventsIn)
  P.embed $ writeChan inc e

-- | Build a Custom CalamityEvent
--
-- The type of @a@ must match up with the event handler you want to receive it.
--
-- ==== Examples
--
-- @
-- 'customEvt' (MyCustomEvent "lol")
-- @
customEvt :: forall a. Typeable a => a -> CalamityEvent
customEvt = Custom

-- | Get a copy of the event stream.
events :: BotC r => P.Sem r (OutChan CalamityEvent)
events = do
  inc <- P.asks (^. #eventsIn)
  P.embed $ dupChan inc

-- | Wait until an event satisfying a condition happens, then returns it's
-- parameters.
--
-- The check function for this command is pure unlike 'waitUntilM'
--
-- This is what it would look like with @s ~ \''MessageCreateEvt'@:
--
-- @
-- 'waitUntil' :: ('Message' -> 'Bool') -> 'P.Sem' r 'Message'
-- @
--
-- And for @s ~ \''MessageUpdateEvt'@:
--
-- @
-- 'waitUntil' :: (('Message', 'Message') -> 'Bool') -> 'P.Sem' r ('Message', 'Message')
-- @
--
-- ==== Examples
--
-- Waiting for a message containing the text \"hi\":
--
-- @
-- f = do msg \<\- 'waitUntil' @\''MessageCreateEvt' (\\m -> 'Data.Text.Lazy.isInfixOf' "hi" $ m ^. #content)
--        print $ msg ^. #content
-- @
waitUntil
  :: forall (s :: EventType) r.
  ( BotC r, ReactConstraints s)
  => (EHType s -> Bool)
  -> P.Sem r (EHType s)
waitUntil f = P.resourceToIOFinal $ do
  result <- P.embed newEmptyMVar
  P.bracket (P.raise $ react @s (checker result))
            P.raise
            (const . P.embed $ takeMVar result)
  where
    checker :: MVar (EHType s) -> EHType s -> P.Sem r ()
    checker result args = do
      when (f args) $ do
        P.embed $ putMVar result args

-- | Wait until an event satisfying a condition happens, then returns it's
-- parameters
--
-- This is what it would look like with @s ~ \''MessageCreateEvt'@:
--
-- @
-- 'waitUntilM' :: ('Message' -> 'P.Sem' r 'Bool') -> 'P.Sem' r 'Message'
-- @
--
-- And for @s ~ \''MessageUpdateEvt'@:
--
-- @
-- 'waitUntilM' :: (('Message', 'Message') -> 'P.Sem' r 'Bool') -> 'P.Sem' r ('Message', 'Message')
-- @
--
-- ==== Examples
--
-- Waiting for a message containing the text \"hi\":
--
-- @
-- f = do msg \<\- 'waitUntilM' @\''MessageCreateEvt' (\\m -> ('debug' $ "got message: " <> 'showt' msg) >> ('pure' $ 'Data.Text.Lazy.isInfixOf' "hi" $ m ^. #content))
--        print $ msg ^. #content
-- @
waitUntilM
  :: forall (s :: EventType) r.
  ( BotC r, ReactConstraints s)
  => (EHType s -> P.Sem r Bool)
  -> P.Sem r (EHType s)
waitUntilM f = P.resourceToIOFinal $ do
  result <- P.embed newEmptyMVar
  P.bracket (P.raise $ react @s (checker result))
            P.raise
            (const . P.embed $ takeMVar result)
  where
    checker :: MVar (EHType s) -> EHType s -> P.Sem r ()
    checker result args = do
      res <- f args
      when res $ do
        P.embed $ putMVar result args

-- | Set the bot's presence on all shards.
sendPresence :: BotC r => StatusUpdateData -> P.Sem r ()
sendPresence s = do
  shards <- P.asks (^. #shards) >>= P.embed . readTVarIO
  for_ shards $ \(inc, _) ->
    P.embed $ writeChan inc (SendPresence s)

-- | Initiate shutting down the bot.
stopBot :: BotC r => P.Sem r ()
stopBot = do
  debug "stopping bot"
  inc <- P.asks (^. #eventsIn)
  P.embed $ writeChan inc ShutDown

finishUp :: BotC r => P.Sem r ()
finishUp = do
  debug "finishing up"
  shards <- P.asks (^. #shards) >>= P.embed . readTVarIO
  for_ shards $ \(inc, _) ->
    P.embed $ writeChan inc ShutDownShard
  for_ shards $ \(_, shardThread) -> P.await shardThread
  debug "bot has stopped"

-- | main loop of the client, handles fetching the next event, processing the
-- event and invoking it's handler functions
clientLoop :: BotC r => P.Sem r ()
clientLoop = do
  outc <- P.asks (^. #eventsOut)
  whileMFinalIO $ do
    !evt' <- P.embed $ readChan outc
    case evt' of
      Dispatch !sid !evt -> handleEvent sid evt >> pure True
      Custom d           -> handleCustomEvent d >> pure True
      ShutDown           -> pure False
  debug "leaving client loop"

handleCustomEvent :: forall a r. (Typeable a, BotC r) => a -> P.Sem r ()
handleCustomEvent d = do
  eventHandlers <- P.atomicGet

  let handlers = getCustomEventHandlers @a eventHandlers

  for_ handlers (\h -> P.async . P.embed $ h d)

catchAllLogging :: BotC r => P.Sem r () -> P.Sem r ()
catchAllLogging m = do
  r <- P.errorToIOFinal . P.fromExceptionSem @SomeException $ P.raise m
  case r of
    Right _ -> pure ()
    Left e -> debug [fmt|got exception: {e:s}|]

handleEvent :: BotC r => Int -> DispatchData -> P.Sem r ()
handleEvent shardID data' = do
  debug "handling an event"
  eventHandlers <- P.atomicGet
  actions <- P.runFail $ do
    evtCounter <- registerCounter "events_received" [("type", S.pack $ ctorName data'), ("shard", showt shardID)]
    void $ addCounter 1 evtCounter
    cacheUpdateHisto <- registerHistogram "cache_update" mempty [10, 20..100]
    (time, res) <- timeA $ resetDi $ handleEvent' eventHandlers data'
    void $ observeHistogram time cacheUpdateHisto
    pure res

  eventHandleHisto <- registerHistogram "event_handle" mempty [10, 20..100]

  case actions of
    Right actions -> for_ actions $ \action -> P.async $ do
      (time, _) <- timeA . catchAllLogging $ P.embed action
      void $ observeHistogram time eventHandleHisto
    -- pattern match failures are usually stuff like events for uncached guilds, etc
    Left err      -> debug [fmt|Failed handling actions for event: {err:s}|]

handleEvent' :: BotC r
              => EventHandlers
              -> DispatchData
              -> P.Sem (P.Fail ': r) [IO ()]
handleEvent' eh evt@(Ready rd@ReadyData {}) = do
  updateCache evt
  pure $ map ($ rd) (getEventHandlers @'ReadyEvt eh)

handleEvent' _ Resumed = pure []

handleEvent' eh evt@(ChannelCreate (DMChannel' chan)) = do
  updateCache evt
  Just newChan <- DMChannel' <<$>> getDM (getID chan)
  pure $ map ($ newChan) (getEventHandlers @'ChannelCreateEvt eh)

handleEvent' eh evt@(ChannelCreate (GuildChannel' chan)) = do
  updateCache evt
  Just guild <- getGuild (getID chan)
  Just newChan <- pure $ GuildChannel' <$> guild ^. #channels . at (getID chan)
  pure $ map ($ newChan) (getEventHandlers @'ChannelCreateEvt eh)

handleEvent' eh evt@(ChannelUpdate (DMChannel' chan)) = do
  Just oldChan <- DMChannel' <<$>> getDM (getID chan)
  updateCache evt
  Just newChan <- DMChannel' <<$>> getDM (getID chan)
  pure $ map ($ (oldChan, newChan)) (getEventHandlers @'ChannelUpdateEvt eh)

handleEvent' eh evt@(ChannelUpdate (GuildChannel' chan)) = do
  Just oldGuild <- getGuild (getID chan)
  Just oldChan <- pure $ GuildChannel' <$> oldGuild ^. #channels . at (getID chan)
  updateCache evt
  Just newGuild <- getGuild (getID chan)
  Just newChan <- pure $ GuildChannel' <$> newGuild ^. #channels . at (getID chan)
  pure $ map ($ (oldChan, newChan)) (getEventHandlers @'ChannelUpdateEvt eh)

handleEvent' eh evt@(ChannelDelete (GuildChannel' chan)) = do
  Just oldGuild <- getGuild (getID chan)
  Just oldChan <- pure $ GuildChannel' <$> oldGuild ^. #channels . at (getID chan)
  updateCache evt
  pure $ map ($ oldChan) (getEventHandlers @'ChannelDeleteEvt eh)

handleEvent' eh evt@(ChannelDelete (DMChannel' chan)) = do
  Just oldChan <- DMChannel' <<$>> getDM (getID chan)
  updateCache evt
  pure $ map ($ oldChan) (getEventHandlers @'ChannelDeleteEvt eh)

-- handleEvent' eh evt@(ChannelPinsUpdate ChannelPinsUpdateData { channelID, lastPinTimestamp }) = do
--   chan <- (GuildChannel' <$> os ^? #channels . at (coerceSnowflake channelID) . _Just)
--     <|> (DMChannel' <$> os ^? #dms . at (coerceSnowflake channelID) . _Just)
--   pure $ map (\f -> f chan lastPinTimestamp) (getEventHandlers @"channelpinsupdate" eh)

handleEvent' eh evt@(GuildCreate guild) = do
  isNew <- not <$> isUnavailableGuild (getID guild)
  updateCache evt
  Just guild <- getGuild (getID guild)
  pure $ map ($ (guild, (if isNew then GuildCreateNew else GuildCreateAvailable)))
    (getEventHandlers @'GuildCreateEvt eh)

handleEvent' eh evt@(GuildUpdate guild) = do
  Just oldGuild <- getGuild (getID guild)
  updateCache evt
  Just newGuild <- getGuild (getID guild)
  pure $ map ($ (oldGuild, newGuild)) (getEventHandlers @'GuildUpdateEvt eh)

-- NOTE: Guild will be deleted in the new cache if unavailable was false
handleEvent' eh evt@(GuildDelete UnavailableGuild { id, unavailable }) = do
  Just oldGuild <- getGuild id
  updateCache evt
  pure $ map ($ (oldGuild, (if unavailable then GuildDeleteUnavailable else GuildDeleteRemoved)))
    (getEventHandlers @'GuildDeleteEvt eh)

handleEvent' eh evt@(GuildBanAdd BanData { guildID, user }) = do
  Just guild <- getGuild guildID
  updateCache evt
  pure $ map ($ (guild, user)) (getEventHandlers @'GuildBanAddEvt eh)

handleEvent' eh evt@(GuildBanRemove BanData { guildID, user }) = do
  Just guild <- getGuild guildID
  updateCache evt
  pure $ map ($ (guild, user)) (getEventHandlers @'GuildBanRemoveEvt eh)

-- NOTE: we fire this event using the guild data with old emojis
handleEvent' eh evt@(GuildEmojisUpdate GuildEmojisUpdateData { guildID, emojis }) = do
  Just guild <- getGuild guildID
  updateCache evt
  pure $ map ($ (guild, emojis)) (getEventHandlers @'GuildEmojisUpdateEvt eh)

handleEvent' eh evt@(GuildIntegrationsUpdate GuildIntegrationsUpdateData { guildID }) = do
  updateCache evt
  Just guild <- getGuild guildID
  pure $ map ($ guild) (getEventHandlers @'GuildIntegrationsUpdateEvt eh)

handleEvent' eh evt@(GuildMemberAdd member) = do
  updateCache evt
  Just guild <- getGuild (getID member)
  Just member <- pure $ guild ^. #members . at (getID member)
  pure $ map ($ member) (getEventHandlers @'GuildMemberAddEvt eh)

handleEvent' eh evt@(GuildMemberRemove GuildMemberRemoveData { user, guildID }) = do
  Just guild <- getGuild guildID
  Just member <- pure $ guild ^. #members . at (getID user)
  updateCache evt
  pure $ map ($ member) (getEventHandlers @'GuildMemberRemoveEvt eh)

handleEvent' eh evt@(GuildMemberUpdate GuildMemberUpdateData { user, guildID }) = do
  Just oldGuild <- getGuild guildID
  Just oldMember <- pure $ oldGuild ^. #members . at (getID user)
  updateCache evt
  Just newGuild <- getGuild guildID
  Just newMember <- pure $ newGuild ^. #members . at (getID user)
  pure $ map ($ (oldMember, newMember)) (getEventHandlers @'GuildMemberUpdateEvt eh)

handleEvent' eh evt@(GuildMembersChunk GuildMembersChunkData { members, guildID }) = do
  updateCache evt
  Just guild <- getGuild guildID
  let memberIDs = map (getID @Member) members
  let members' = catMaybes $ map (\mid -> guild ^. #members . at mid) memberIDs
  pure $ map ($ (guild, members')) (getEventHandlers @'GuildMembersChunkEvt eh)

handleEvent' eh evt@(GuildRoleCreate GuildRoleData { guildID, role }) = do
  updateCache evt
  Just guild <- getGuild guildID
  Just role' <- pure $ guild ^. #roles . at (getID role)
  pure $ map ($ (guild, role')) (getEventHandlers @'GuildRoleCreateEvt eh)

handleEvent' eh evt@(GuildRoleUpdate GuildRoleData { guildID, role }) = do
  Just oldGuild <- getGuild guildID
  Just oldRole <- pure $ oldGuild ^. #roles . at (getID role)
  updateCache evt
  Just newGuild <- getGuild guildID
  Just newRole <- pure $ newGuild ^. #roles . at (getID role)
  pure $ map ($ (newGuild, oldRole, newRole)) (getEventHandlers @'GuildRoleUpdateEvt eh)

handleEvent' eh evt@(GuildRoleDelete GuildRoleDeleteData { guildID, roleID }) = do
  Just guild <- getGuild guildID
  Just role <- pure $ guild ^. #roles . at roleID
  updateCache evt
  pure $ map ($ (guild, role)) (getEventHandlers @'GuildRoleDeleteEvt eh)

handleEvent' eh (InviteCreate d) = do
  pure $ map ($ d) (getEventHandlers @'InviteCreateEvt eh)

handleEvent' eh (InviteDelete d) = do
  pure $ map ($ d) (getEventHandlers @'InviteDeleteEvt eh)

handleEvent' eh evt@(MessageCreate msg _) = do
  updateCache evt
  pure $ map ($ msg) (getEventHandlers @'MessageCreateEvt eh)

handleEvent' eh evt@(MessageUpdate msg) = do
  oldMsg <- getMessage (getID msg)
  updateCache evt
  newMsg <- getMessage (getID msg)
  let rawActions = map ($ msg) (getEventHandlers @'RawMessageUpdateEvt eh)
  let actions = case (oldMsg, newMsg) of
                  (Just oldMsg', Just newMsg') ->
                    map ($ (oldMsg', newMsg')) (getEventHandlers @'MessageUpdateEvt eh)
                  _ -> []
  pure $ rawActions <> actions

handleEvent' eh evt@(MessageDelete MessageDeleteData { id }) = do
  oldMsg <- getMessage id
  updateCache evt
  let rawActions = map ($ id) (getEventHandlers @'RawMessageDeleteEvt eh)
  let actions = case oldMsg of
        Just oldMsg' ->
          map ($ oldMsg') (getEventHandlers @'MessageDeleteEvt eh)
        _ -> []
  pure $ rawActions <> actions

handleEvent' eh evt@(MessageDeleteBulk MessageDeleteBulkData { ids }) = do
  messages <- catMaybes <$> traverse getMessage ids
  updateCache evt
  let rawActions = map ($ ids) (getEventHandlers @'RawMessageDeleteBulkEvt eh)
  let actions = map ($ messages) (getEventHandlers @'MessageDeleteBulkEvt eh)
  pure $ rawActions <> actions

handleEvent' eh evt@(MessageReactionAdd reaction) = do
  updateCache evt
  msg <- getMessage (getID reaction)
  user <- getUser (getID reaction)
  chan <- case reaction ^. #guildID of
    Just _ -> do
      chan <- getGuildChannel (coerceSnowflake $ getID @Channel reaction)
      pure (GuildChannel' <$> chan)
    Nothing -> do
      chan <- getDM (coerceSnowflake $ getID @Channel reaction)
      pure (DMChannel' <$> chan)
  let rawActions = map ($ reaction) (getEventHandlers @'RawMessageReactionAddEvt eh)
  let actions = case (msg, user, chan) of
        (Just msg', Just user', Just chan') ->
          map ($ (msg', user', chan', reaction ^. #emoji)) (getEventHandlers @'MessageReactionAddEvt eh)
        _ -> []
  pure $ rawActions <> actions

handleEvent' eh evt@(MessageReactionRemove reaction) = do
  msg <- getMessage (getID reaction)
  updateCache evt
  user <- getUser (getID reaction)
  chan <- case reaction ^. #guildID of
    Just _ -> do
      chan <- getGuildChannel (coerceSnowflake $ getID @Channel reaction)
      pure (GuildChannel' <$> chan)
    Nothing -> do
      chan <- getDM (coerceSnowflake $ getID @Channel reaction)
      pure (DMChannel' <$> chan)
  let rawActions = map ($ reaction) (getEventHandlers @'RawMessageReactionRemoveEvt eh)
  let actions = case (msg, user, chan) of
        (Just msg', Just user', Just chan') ->
          map ($ (msg', user', chan', reaction ^. #emoji)) (getEventHandlers @'MessageReactionRemoveEvt eh)
        _ -> []
  pure $ rawActions <> actions

handleEvent' eh evt@(MessageReactionRemoveAll MessageReactionRemoveAllData { messageID }) = do
  msg <- getMessage messageID
  updateCache evt
  let rawActions = map ($ messageID) (getEventHandlers @'RawMessageReactionRemoveAllEvt eh)
  let actions = case msg of
        Just msg' ->
          map ($ msg') (getEventHandlers @'MessageReactionRemoveAllEvt eh)
        _ -> []
  pure $ rawActions <> actions

handleEvent' eh evt@(PresenceUpdate PresenceUpdateData { userID, presence = Presence { guildID } }) = do
  Just oldGuild <- getGuild guildID
  Just oldMember <- pure $ oldGuild ^. #members . at (coerceSnowflake userID)
  updateCache evt
  Just newGuild <- getGuild guildID
  Just newMember <- pure $ newGuild ^. #members . at (coerceSnowflake userID)
  let oldUser :: User = upcast oldMember
      newUser :: User = upcast newMember
      userUpdates = if oldUser /= newUser
                    then map ($ (oldUser, newUser)) (getEventHandlers @'UserUpdateEvt eh)
                    else mempty
  pure $ userUpdates <> map ($ (oldMember, newMember)) (getEventHandlers @'GuildMemberUpdateEvt eh)

handleEvent' eh (TypingStart TypingStartData { channelID, guildID, userID, timestamp = UnixTimestamp timestamp }) =
  case guildID of
    Just gid -> do
      Just guild <- getGuild gid
      Just chan <- pure $ GuildChannel' <$> guild ^. #channels . at (coerceSnowflake channelID)
      pure $ map ($ (chan, userID, timestamp)) (getEventHandlers @'TypingStartEvt eh)
    Nothing -> do
      Just chan <- DMChannel' <<$>> getDM (coerceSnowflake channelID)
      pure $ map ($ (chan, userID, timestamp)) (getEventHandlers @'TypingStartEvt eh)

handleEvent' eh evt@(UserUpdate _) = do
  Just oldUser <- getBotUser
  updateCache evt
  Just newUser <- getBotUser
  pure $ map ($ (oldUser, newUser)) (getEventHandlers @'UserUpdateEvt eh)

handleEvent' eh evt@(VoiceStateUpdate newVoiceState@V.VoiceState{guildID=Just guildID}) = do
  oldVoiceState <- ((find ((== V.sessionID newVoiceState) . V.sessionID) . voiceStates) =<<) <$> getGuild guildID
  updateCache evt
  pure $ map ($ (oldVoiceState, newVoiceState)) (getEventHandlers @'VoiceStateUpdateEvt eh)

handleEvent' _ e = fail $ "Unhandled event: " <> show e

updateCache :: P.Members '[CacheEff, P.Fail] r => DispatchData -> P.Sem r ()
updateCache (Ready ReadyData { user, guilds }) = do
  setBotUser user
  for_ (map getID guilds) setUnavailableGuild

updateCache Resumed = pure ()

updateCache (ChannelCreate (DMChannel' chan)) =
  setDM chan

updateCache (ChannelCreate (GuildChannel' chan)) =
  updateGuild (getID chan) (#channels %~ SM.insert chan)

updateCache (ChannelUpdate (DMChannel' chan)) =
  updateDM (getID chan) (update chan)

updateCache (ChannelUpdate (GuildChannel' chan)) =
  updateGuild (getID chan) (#channels . ix (getID chan) %~ update chan)

updateCache (ChannelDelete (DMChannel' chan)) =
  delDM (getID chan)

updateCache (ChannelDelete (GuildChannel' chan)) =
  updateGuild (getID chan) (#channels %~ sans (getID chan))

updateCache (GuildCreate guild) = do
  isNew <- isUnavailableGuild (getID guild)
  when isNew $ delUnavailableGuild (getID guild)
  setGuild guild
  for_ (SM.fromList (guild ^.. #members . traverse . super)) setUser

updateCache (GuildUpdate guild) =
  updateGuild (getID guild) (update guild)

updateCache (GuildDelete UnavailableGuild { id, unavailable }) =
  if unavailable
  then setUnavailableGuild id
  else delGuild id

updateCache (GuildEmojisUpdate GuildEmojisUpdateData { guildID, emojis }) =
  updateGuild guildID (#emojis .~ SM.fromList emojis)

updateCache (GuildMemberAdd member) = do
  setUser (member ^. super)
  updateGuild (getID member) (#members . at (getID member) ?~ member)

updateCache (GuildMemberRemove GuildMemberRemoveData { guildID, user }) =
  updateGuild guildID (#members %~ sans (getID user))

updateCache (GuildMemberUpdate GuildMemberUpdateData { guildID, roles = AesonVector roles, user, nick }) = do
  setUser user
  updateGuild guildID (#members . ix (getID user) %~ (#roles .~ roles) . (#nick .~ nick))

updateCache (GuildMembersChunk GuildMembersChunkData { members }) =
  traverse_ (updateCache . GuildMemberAdd) members

updateCache (GuildRoleCreate GuildRoleData { guildID, role }) =
  updateGuild guildID (#roles %~ SM.insert role)

updateCache (GuildRoleUpdate GuildRoleData { guildID, role }) =
  updateGuild guildID (#roles %~ SM.insert role)

updateCache (GuildRoleDelete GuildRoleDeleteData { guildID, roleID }) =
  updateGuild guildID (#roles %~ sans roleID)

updateCache (MessageCreate !msg !user) = do
  setMessage msg
  for_ user setUser

updateCache (MessageUpdate msg) =
  updateMessage (getID msg) (update msg)

updateCache (MessageDelete MessageDeleteData { id }) = delMessage id

updateCache (MessageDeleteBulk MessageDeleteBulkData { ids }) =
  for_ ids delMessage

updateCache (MessageReactionAdd reaction) = do
  isMe <- (\u -> Just (getID @User reaction) == (getID @User <$> u)) <$> getBotUser
  updateMessage
    (getID reaction)
    ( \m ->
        case m ^. #reactions & filter ((== (reaction ^. #emoji)) . (^. #emoji)) of
          [] -> m & #reactions <>~ [Reaction 1 isMe (reaction ^. #emoji)]
          _ ->
            m & #reactions . traverse . filtered ((== (reaction ^. #emoji)) . (^. #emoji))
              %~ (#count +~ 1) . (#me ||~ isMe)
    )
updateCache (MessageReactionRemove reaction) = do
  isMe <- (\u -> Just (getID @User reaction) == (getID @User <$> u)) <$> getBotUser
  updateMessage
    (getID reaction)
    ( \m ->
        m
          & #reactions . traverse . filtered ((== (reaction ^. #emoji)) . (^. #emoji))
            %~ (#count -~ 1) . (#me &&~ not isMe)
          & #reactions %~ filter (\r -> r ^. #count /= 0)
    )

updateCache (MessageReactionRemoveAll MessageReactionRemoveAllData { messageID }) =
  updateMessage messageID (#reactions .~ mempty)

updateCache (PresenceUpdate PresenceUpdateData { userID, presence }) =
  updateGuild (getID presence) (#presences . at userID ?~ presence)

updateCache (UserUpdate user) = setBotUser user

-- we don't handle group channels currently
updateCache (ChannelCreate (GroupChannel' _)) = pure ()
updateCache (ChannelUpdate (GroupChannel' _)) = pure ()
updateCache (ChannelDelete (GroupChannel' _)) = pure ()

-- these don't modify state
updateCache (GuildBanAdd _) = pure ()
updateCache (GuildBanRemove _) = pure ()
updateCache (GuildIntegrationsUpdate _) = pure ()
updateCache (TypingStart _) = pure ()
updateCache (ChannelPinsUpdate _) = pure ()
updateCache (WebhooksUpdate _) = pure ()
updateCache (InviteCreate _) = pure ()
updateCache (InviteDelete _) = pure ()

updateCache (VoiceStateUpdate voiceState@V.VoiceState{guildID=Just guildID}) =
  updateGuild guildID (#voiceStates %~ updateVoiceStates)
  where
    updateVoiceStates [] = [voiceState]
    updateVoiceStates (x:xs)
        | V.sessionID x == V.sessionID voiceState = voiceState : xs
        | otherwise = x : updateVoiceStates xs

  -- we don't handle voice server update and direct voice connections currently
updateCache (VoiceStateUpdate V.VoiceState{guildID=Nothing}) = pure ()
updateCache (VoiceServerUpdate _) = pure ()