module Test.FSM
  (
    unitTests
  ) where

import           Control.Concurrent.STM.TVar (readTVarIO)
import           FSM
import           System.Timeout              (timeout)
import           Test.Tasty
import           Test.Tasty.HUnit            (testCase, (@?=))

unitTests :: TestTree
unitTests = testGroup "FSM"
  [ testSimpleStateChange
  , testStateWithoutCallback ]

data SimpleState =
    StateInitial
  | StateIntermediate
  | StateFinal
  deriving (Show, Eq, Ord)

instance FSMState SimpleState where
  isTerminalState StateFinal = True
  isTerminalState _          = False

testSimpleStateChange = testCase "Simple state change" $ do
  fsm <- makeFsm StateInitial [(StateInitial, callbackChangeState StateIntermediate),
                               (StateIntermediate, callbackChangeState StateFinal),
                               (StateFinal, doNothing)]
  timeout 100000 $ runFsm fsm
  endState <- readTVarIO (fsmCurrentState fsm)
  endState @?= StateFinal
  where
    callbackChangeState x = FSMCallback (pure $ Just x)
    doNothing = FSMCallback (pure Nothing)

testStateWithoutCallback = testCase "Test without callback" $ do
  fsm <- makeFsm StateInitial [(StateInitial, callbackChangeState StateIntermediate),
                               (StateFinal, doNothing)]
  timeout 100000 $ runFsm fsm
  endState <- readTVarIO (fsmCurrentState fsm)
  endState @?= StateIntermediate
  where
    callbackChangeState x = FSMCallback (pure $ Just x)
    doNothing = FSMCallback (pure Nothing)