{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeApplications #-}

-- | Swarm unit tests
module Main where

import Control.Monad.Except (runExceptT)
import Data.List (subsequences)
import Data.Set (Set)
import Data.Set qualified as S
import Swarm.Game.State (GameState, classicGame0)
import Swarm.Util (smallHittingSet)
import Test.QuickCheck qualified as QC
import Test.QuickCheck.Poly qualified as QC
import Test.Tasty (TestTree, defaultMain, testGroup)
import Test.Tasty.HUnit (assertFailure)
import Test.Tasty.QuickCheck (
  Arbitrary (arbitrary),
  Property,
  testProperty,
  (==>),
 )
import TestEval (testEval)
import TestInventory (testInventory)
import TestLanguagePipeline (testLanguagePipeline)
import TestModel (testModel)
import TestNotification (testNotification)
import TestPretty (testPrettyConst)
import Witch (from)

main :: IO ()
main = do
  mg <- runExceptT classicGame0
  case mg of
    Left err -> assertFailure (from err)
    Right g -> defaultMain (tests g)

tests :: GameState -> TestTree
tests g =
  testGroup
    "Tests"
    [ testLanguagePipeline
    , testPrettyConst
    , testEval g
    , testModel
    , testInventory
    , testNotification g
    , testMisc
    ]

testMisc :: TestTree
testMisc =
  testGroup
    "Miscellaneous"
    [ testProperty
        "smallHittingSet produces hitting sets"
        (prop_hittingSet @QC.OrdA)
    ]

prop_hittingSet :: Ord a => [Set a] -> Property
prop_hittingSet ss = not (any S.null ss) ==> isHittingSet (smallHittingSet ss) ss

isHittingSet :: (Foldable t, Ord a) => Set a -> t (Set a) -> Bool
isHittingSet hs = not . any (S.null . S.intersection hs)

-- This property does *not* hold (and should not, because the problem
-- of producing a minimal hitting set is NP-hard), but we can use it
-- to generate counterexamples.
prop_hittingSetMinimal :: [Set El] -> Property
prop_hittingSetMinimal ss = not (any S.null ss) ==> all ((S.size hs <=) . S.size) allHittingSets
 where
  allElts = S.unions ss
  allSubsets = map S.fromList . subsequences . S.toList $ allElts
  allHittingSets = filter (`isHittingSet` ss) allSubsets
  hs = smallHittingSet ss

-- Five elements seem to be the minimum necessary for a
-- counterexample, but providing 6 helps QuickCheck find a
-- counterexample much more quickly.
data El = AA | BB | CC | DD | EE | FF
  deriving (Eq, Ord, Show, Bounded, Enum)

instance QC.Arbitrary El where
  arbitrary = QC.arbitraryBoundedEnum