{-# LANGUAGE RecursiveDo #-}

module Reflex.Data.StackSpec
  ( 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.Stack
import           Reflex.Potato.Helpers
import           Reflex.Test.Host

data TestCmd a = TCPush a | TCPop | 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 pushEv = flip fmapMaybe ev $ \case
        TCPush n -> Just n
        _        -> Nothing
      popEv = flip fmapMaybe ev $ \case
        TCPop -> Just ()
        _     -> Nothing
      clearEv = flip fmapMaybe ev $ \case
        TCClear -> Just ()
        _       -> Nothing

      mds = DynamicStackConfig { _dynamicStackConfig_push  = pushEv
                               , _dynamicStackConfig_pop   = popEv
                               , _dynamicStackConfig_clear = clearEv
                               }
  ds :: DynamicStack t a <- holdDynamicStack [] mds
  adder :: Dynamic t s   <- foldDynMergeWith
    initial
    [fmap fdo (_dynamicStack_pushed ds), fmap fundo (_dynamicStack_popped ds)]
  return $ updated adder

adder_test :: Test
adder_test = TestLabel "adder app" $ TestCase $ do
  let bs =
        fmap TCPush [1 .. 4]
          <> fmap (const TCPop) [(), (), (), (), (), (), ()]
          <> fmap TCPush        [100]
      run = runAppSimple (simple_state_network (+) (flip (-)) (0 :: Int)) bs
  v <- liftIO run
  L.last v @?= [Just 100]


clear_test_network
  :: forall t m
   . (t ~ SpiderTimeline Global, m ~ SpiderHost Global)
  => (Event t (TestCmd Int) -> PerformEventT t m (Event t [Int]))
clear_test_network ev = do
  let pushEv = flip fmapMaybe ev $ \case
        TCPush n -> Just n
        _        -> Nothing
      popEv   = fmapMaybe (\x -> if x == TCPop then Just () else Nothing) ev
      clearEv = fmapMaybe (\x -> if x == TCClear then Just () else Nothing) ev

      mds     = DynamicStackConfig { _dynamicStackConfig_push  = pushEv
                                   , _dynamicStackConfig_pop   = popEv
                                   , _dynamicStackConfig_clear = clearEv
                                   }
  ds :: DynamicStack t Int <- holdDynamicStack
    []
    (mds :: DynamicStackConfig t Int)
  return $ updated (_dynamicStack_contents ds)

clear_test :: Test
clear_test = TestLabel "clear" $ TestCase $ do
  let bs =
        fmap TCPush [1 .. 13]
          <> fmap (const TCPop) [(), (), ()]
          <> [TCClear]
          <> fmap TCPush [100]
      run = runAppSimple clear_test_network bs
  v <- liftIO run
  L.last v @?= [Just [100]]


basic_test_network
  :: forall t m
   . (t ~ SpiderTimeline Global, m ~ SpiderHost Global)
  => (Event t (Either Int ()) -> PerformEventT t m (Event t [Int]))
basic_test_network ev = do
  let pushEv = fmapMaybe getLeft ev
      popEv  = fmapMaybe getRight ev

      mds    = DynamicStackConfig { _dynamicStackConfig_push  = pushEv
                                  , _dynamicStackConfig_pop   = popEv
                                  , _dynamicStackConfig_clear = never
                                  }
  ds :: DynamicStack t Int <- holdDynamicStack
    []
    (mds :: DynamicStackConfig t Int)
  return $ updated (_dynamicStack_contents ds)

basic_test :: Test
basic_test = TestLabel "basic" $ TestCase $ do
  let bs  = fmap Left [1 .. 13] <> fmap Right [(), (), ()] :: [Either Int ()]
      run = runAppSimple basic_test_network bs
  v <- liftIO run
  L.last v @?= [Just (drop (length (rights bs)) . reverse $ lefts bs)]

spec :: Spec
spec = do
  describe "Stack" $ do
    fromHUnitTest basic_test
    fromHUnitTest clear_test
    fromHUnitTest adder_test