-- |
-- Module      : Reflex.Dom.Retractable.Trans.Internal
-- Copyright   : (c) 2019 ATUM SOLUTIONS AG
-- License     : MIT
-- Maintainer  : ncrashed@protonmail.com
-- Stability   : unstable
-- Portability : non-portable
--
-- Plug-in implementation for `MonadRetract` using wrapper around `ReaderT`.
-- Internal module, implementation details can be changed at any moment.
module Reflex.Dom.Retractable.Trans.Internal where

import Control.Monad.Reader
import Control.Monad.Ref
import Control.Monad.State.Strict
import GHC.Generics
import Language.Javascript.JSaddle.Types
import Reflex
import Reflex.Dom
import Reflex.Dom.Retractable.Class
import Reflex.Host.Class

-- | Helper to simplify types in `RetractEnv`
type RetractableT t m = Retractable t (RetractT t m)

-- | Internal state of retractable widget
data RetractEnv t m = RetractEnv
  { renvNextFire     :: !(RetractableT t m -> IO ())
  , renvNextEvent    :: !(Event t (RetractableT t m))
  , renvRetractFire  :: !(IO ())
  , renvRetractEvent :: !(Event t ())
  , renvWipeFire     :: !(Maybe Int -> IO ())
  , renvWipeEvent    :: !(Event t (Maybe Int))
  , renvStack        :: !(Dynamic t [RetractableT t m])
  } deriving (Generic)

-- | Allocate new environment for `RetracT`.
newRetractEnv :: (Reflex t, TriggerEvent t m) => m (RetractEnv t m)
newRetractEnv = do
  (nextE, nextFire) <- newTriggerEvent
  (retrE, retrFire) <- newTriggerEvent
  (wipeE, wipeFire) <- newTriggerEvent
  pure RetractEnv {
      renvNextFire     = nextFire
    , renvNextEvent    = nextE
    , renvRetractFire  = retrFire ()
    , renvRetractEvent = retrE
    , renvWipeFire     = wipeFire
    , renvWipeEvent    = wipeE
    , renvStack        = pure []
    }

-- | Plug-in implementation of `MonadRetract`.
newtype RetractT t m a = RetractT { unRetractT :: ReaderT (RetractEnv t m) m a }
  deriving (Functor, Applicative, Monad, Generic, MonadFix, MonadRef, HasJSContext, HasDocument)

deriving instance PostBuild t m => PostBuild t (RetractT t m)
deriving instance NotReady t m => NotReady t (RetractT t m)
deriving instance PerformEvent t m => PerformEvent t (RetractT t m)
deriving instance TriggerEvent t m => TriggerEvent t (RetractT t m)
deriving instance MonadHold t m => MonadHold t (RetractT t m)
deriving instance MonadSample t m => MonadSample t (RetractT t m)
deriving instance DomBuilder t m => DomBuilder t (RetractT t m)
deriving instance MonadIO m => MonadIO (RetractT t m)
deriving instance MonadJSM m => MonadJSM (RetractT t m)
deriving instance (Group q, Additive q, Query q, Eq q, MonadQuery t q m, Monad m) => MonadQuery t q (RetractT t m)
deriving instance (Monoid w, DynamicWriter t w m) => DynamicWriter t w (RetractT t m)
deriving instance (Monoid w, MonadBehaviorWriter t w m) => MonadBehaviorWriter t w (RetractT t m)
deriving instance (Semigroup w, EventWriter t w m) => EventWriter t w (RetractT t m)
deriving instance (Requester t m) => Requester t (RetractT t m)
deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (RetractT t m)

instance MonadTrans (RetractT t) where
  lift = RetractT . lift
  {-# INLINABLE lift #-}

instance MonadReader e m => MonadReader e (RetractT t m) where
  ask = lift ask
  {-# INLINABLE ask #-}
  local f (RetractT ma) = RetractT $ do
    r <- ask
    lift $ local f $ runReaderT ma r
  {-# INLINABLE local #-}

instance MonadState s m => MonadState s (RetractT t m) where
  get = lift get
  {-# INLINABLE get #-}
  put = lift . put
  {-# INLINABLE put #-}

instance Adjustable t m => Adjustable t (RetractT t m) where
  runWithReplace a0 a' = do
    r <- RetractT ask
    lift $ runWithReplace (runRetractT a0 r) $ fmap (`runRetractT` r) a'
  {-# INLINABLE runWithReplace #-}
  traverseIntMapWithKeyWithAdjust f dm0 dm' = do
    r <- RetractT ask
    lift $ traverseIntMapWithKeyWithAdjust (\k v -> runRetractT (f k v) r) dm0 dm'
  {-# INLINABLE traverseIntMapWithKeyWithAdjust #-}
  traverseDMapWithKeyWithAdjust f dm0 dm' = do
    r <- RetractT ask
    lift $ traverseDMapWithKeyWithAdjust (\k v -> runRetractT (f k v) r) dm0 dm'
  {-# INLINABLE traverseDMapWithKeyWithAdjust #-}
  traverseDMapWithKeyWithAdjustWithMove f dm0 dm' = do
    r <- RetractT ask
    lift $ traverseDMapWithKeyWithAdjustWithMove (\k v -> runRetractT (f k v) r) dm0 dm'
  {-# INLINABLE traverseDMapWithKeyWithAdjustWithMove #-}

-- | Execute retractable widget with given environment.
runRetractT :: RetractT t m a -> RetractEnv t m -> m a
runRetractT (RetractT ma) e = runReaderT ma e
{-# INLINEABLE runRetractT #-}

-- | Simplified version of `runRetractT`
runRetract :: (Reflex t, TriggerEvent t m) => RetractT t m a -> m a
runRetract ma = do
  re <- newRetractEnv
  runRetractT ma re
{-# INLINABLE runRetract #-}

instance (PerformEvent t m, MonadHold t m, Adjustable t m, MonadFix m, MonadIO (Performable m))
  => MonadRetract t (RetractT t m) where
  nextWidget e = do
    fire <- RetractT $ asks renvNextFire
    performEvent $ fmap (liftIO . fire) e
  {-# INLINEABLE nextWidget #-}

  retract e = do
    fire <- RetractT $ asks renvRetractFire
    performEvent $ (liftIO fire) <$ e
  {-# INLINEABLE retract #-}

  wipeRetract e = do
    fire <- RetractT $ asks renvWipeFire
    performEvent $ fmap (liftIO . fire) e
  {-# INLINEABLE wipeRetract #-}

  nextWidgetEvent = RetractT $ asks renvNextEvent
  {-# INLINABLE nextWidgetEvent #-}

  retractEvent = RetractT $ asks renvRetractEvent
  {-# INLINABLE retractEvent #-}

  wipeRetractEvent = RetractT $ asks renvWipeEvent
  {-# INLINABLE wipeRetractEvent #-}

  getRetractStack = RetractT $ asks renvStack
  {-# INLINEABLE getRetractStack #-}

  withRetractStack st (RetractT ma) = RetractT $ local (\r -> r { renvStack = st }) ma
  {-# INLINEABLE withRetractStack #-}