{-# OPTIONS_GHC -fno-warn-orphans #-}

module AutoTupleSpec where

import Data.Either (isRight)
import OccName (mkVarOcc)
import System.IO.Unsafe
import Test.Hspec
import Test.QuickCheck
import Type (mkTyVarTy)
import TysPrim (alphaTyVars)
import TysWiredIn (mkBoxedTupleTy)
import Wingman.Judgements (mkFirstJudgement)
import Wingman.Machinery
import Wingman.Tactics (auto')
import Wingman.Types


spec :: Spec
spec = describe "auto for tuple" $ do
  it "should always be able to discover an auto solution" $ do
    property $ do
      -- Pick some number of variables
      n <- choose (1, 7)
      let vars = fmap mkTyVarTy $ take n alphaTyVars
      -- Pick a random ordering
      in_vars  <- shuffle vars
      -- Randomly associate them into tuple types
      in_type  <- mkBoxedTupleTy
                . fmap mkBoxedTupleTy
              <$> randomGroups in_vars
      out_type <- mkBoxedTupleTy
                . fmap mkBoxedTupleTy
              <$> randomGroups vars
      pure $
          -- We should always be able to find a solution
          unsafePerformIO
            (runTactic
              emptyContext
              (mkFirstJudgement
                emptyContext
                (Hypothesis $ pure $ HyInfo (mkVarOcc "x") UserPrv $ CType in_type)
                True
                out_type)
              (auto' $ n * 2)) `shouldSatisfy` isRight


randomGroups :: [a] -> Gen [[a]]
randomGroups [] = pure []
randomGroups as = do
  n <- choose (1, length as)
  (:) <$> pure (take n as)
      <*> randomGroups (drop n as)