{-# LANGUAGE RecursiveDo #-}

module Reflex.Data.ActionStackSpec
  ( spec
  )
where

import           Relude

import           Test.Hspec
import           Test.Hspec.Contrib.HUnit       ( fromHUnitTest )
import           Test.HUnit

import qualified Data.List                     as L
                                                ( last )

import           Reflex
import           Reflex.Data.ActionStack
import           Reflex.Potato.Helpers
import           Reflex.Test.Host

data TestCmd a = TCDo a | TCUndo | TCRedo | TCClear deriving (Eq, Show)

simple_state_network
  :: forall t a s m
   . (t ~ SpiderTimeline Global, m ~ SpiderHost Global)
  => (a -> s -> s) -- ^ do/redo method to transform state
  -> (a -> s -> s) -- ^ undo method to transform state
  -> s -- ^ initial state
  -> (Event t (TestCmd a) -> PerformEventT t m (Event t s)) -- ^ test app producing final state
simple_state_network fdo fundo initial ev = do
  let doEv = flip fmapMaybe ev $ \case
        TCDo a -> Just a
        _      -> Nothing
      undoEv = flip fmapMaybe ev $ \case
        TCUndo -> Just ()
        _      -> Nothing
      redoEv = flip fmapMaybe ev $ \case
        TCRedo -> Just ()
        _      -> Nothing
      clearEv = flip fmapMaybe ev $ \case
        TCClear -> Just ()
        _       -> Nothing

      mas = ActionStackConfig { _actionStackConfig_do    = doEv
                              , _actionStackConfig_undo  = undoEv
                              , _actionStackConfig_redo  = redoEv
                              , _actionStackConfig_clear = clearEv
                              }
  as :: ActionStack t a <- holdActionStack mas
  adder :: Dynamic t s  <- foldDynMergeWith
    initial
    [fmap fdo (_actionStack_do as), fmap fundo (_actionStack_undo as)]
  return $ updated adder

adder_test :: Test
adder_test = TestLabel "adder app" $ TestCase $ do
  let bs  = [TCDo 1, TCDo 2, TCDo 3, TCUndo, TCUndo, TCRedo, TCDo 100]
      run = runAppSimple (simple_state_network (+) (flip (-)) (0 :: Int)) bs
  v <- liftIO run
  L.last v @?= [Just 103]

spec :: Spec
spec = do
  describe "ActionStack" $ do
    fromHUnitTest adder_test